Avinger (AVGR) S-1 13 Jan 20 2019 Q3 IPO registration Financial data

Document And Entity Information

Document And Entity Information	9 Months Ended
	Sep. 30, 2019
Document Information [Line Items]
Entity Registrant Name	Avinger Inc
Entity Central Index Key	0001506928
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Small Business	true
Document Type	S-1
Document Period End Date	Sep. 30, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Balance Sheets (Curre

Condensed Balance Sheets (Current Period Unaudited) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Current assets:
Cash and cash equivalents	$ 14,461,000	$ 16,410,000
Accounts receivable, net of allowance for doubtful accounts of $185 and $260 at September 30, 2019 and December 31, 2018, respectively	1,301,000	1,154,000
Inventories	4,112,000	3,422,000
Prepaid expenses and other current assets	489,000	635,000
Total current assets	20,363,000	21,621,000
Right of use asset	5,192,000
Property and equipment, net	1,873,000	2,078,000
Other assets	579,000
Total assets	28,007,000	23,699,000
Current liabilities:
Accounts payable	919,000	1,148,000
Accrued compensation	1,189,000	1,197,000
Accrued expenses and other current liabilities	681,000	1,449,000
Leasehold liability, current portion	855,000
Borrowings	8,578,000	7,486,000
Preferred stock dividends payable	2,685,000	2,918,000
Total current liabilities	14,907,000	14,198,000
Leasehold liability, long-term portion	4,337,000
Other long-term liabilities	9,000	41,000
Total liabilities	19,253,000	14,239,000
Commitments and contingencies (Note 6)
Stockholders’ equity:
Convertible preferred stock issuable in series, par value of $0.001 Shares authorized: 5,000,000 at June 30, 2019 and December 31, 2018 Shares issued and outstanding: 44,923 and 45,671 at June 30, 2019 and December 31, 2018, respectively; aggregate liquidation preference of $46,535 and $44,718 at June 30, 2019 and December 31, 2018, respectively
Common stock, par value of $0.001; Shares authorized: 100,000,000 at September 30, 2019 and December 31, 2018; Shares issued and outstanding: 10,342,179 and 3,492,200 at September 30, 2019 and December 31, 2018, respectively	10,000	3,000
Additional paid-in capital	351,958,000	338,342,000
Accumulated deficit	(343,214,000)	(328,885,000)
Total stockholders’ equity	8,754,000	9,460,000
Total liabilities and stockholders’ equity	$ 28,007,000	$ 23,699,000

Condensed Balance Sheets (Cur_2

Condensed Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Feb. 16, 2018	Dec. 31, 2017
Allowance for doubtful accounts	$ 185	$ 260		$ 146
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000		5,000,000
Preferred stock, shares issued (in shares)	44,923	45,671		0
Preferred stock, shares outstanding (in shares)	44,923	45,671		0
Preferred stock, liquidation value	$ 47,430	$ 44,718		$ 0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001		$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000		100,000,000
Common stock, shares issued (in shares)	10,342,179	3,492,200		83,360
Common stock, shares outstanding (in shares)	10,342,179	3,492,200		83,360

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Revenues	$ 2,410	$ 2,020	$ 6,569	$ 5,887	$ 7,915	$ 9,934
Cost of revenues	1,563	1,477	4,629	5,061	6,531	13,002
Gross profit	847	543	1,940	826	1,384	(3,068)
Operating expenses:
Research and development	1,371	1,404	4,120	4,340	6,009	11,319
Selling, general and administrative	4,091	4,499	12,168	13,443	17,442	25,120
Total operating expenses	5,462	5,903	16,288	17,783	23,451	39,484
Loss from operations	(4,615)	(5,360)	(14,348)	(16,957)	(22,067)	(42,552)
Interest income	70	54	242	137	214	108
Interest expense	(377)	(324)	(1,091)	(5,358)	(5,692)	(6,299)
Other income net	299	242	868	710	(13)	11
Net loss and comprehensive loss	(4,623)	(5,388)	(14,329)	(21,468)	(27,558)	(48,732)
Accretion of preferred stock dividends	(895)	(836)	(2,685)	(2,082)	(2,918)
Deemed dividend arising from beneficial conversion feature of convertible preferred stock				(5,216)	(5,216)
Net loss attributable to common stockholders	$ (5,518)	$ (6,224)	$ (17,014)	$ (28,766)	$ (35,692)	$ (48,732)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.70)	$ (5.56)	$ (2.75)	$ (43)	$ (33.42)	$ (749.72)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	7,900	1,119	6,189	669	1,068	65

Condensed Statements of Stockho

Condensed Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]Preferred Stock [Member]	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]Common Stock [Member]	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]Additional Paid-in Capital [Member]	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]Retained Earnings [Member]	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]	Conversion of CRG into Series A Preferred Stock [Member]Preferred Stock [Member]	Conversion of CRG into Series A Preferred Stock [Member]Common Stock [Member]	Conversion of CRG into Series A Preferred Stock [Member]Additional Paid-in Capital [Member]	Conversion of CRG into Series A Preferred Stock [Member]Retained Earnings [Member]	Conversion of CRG into Series A Preferred Stock [Member]	Conversion of Series B Preferred Stock into Common Stock [Member]Preferred Stock [Member]	Conversion of Series B Preferred Stock into Common Stock [Member]Common Stock [Member]	Conversion of Series B Preferred Stock into Common Stock [Member]Additional Paid-in Capital [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]Preferred Stock [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]Common Stock [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]Additional Paid-in Capital [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]Retained Earnings [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]	Series B Preferred Stock [Member]Preferred Stock [Member]	Series B Preferred Stock [Member]Additional Paid-in Capital [Member]	Series B Preferred Stock [Member]	Series A Preferred Stock [Member]Preferred Stock [Member]	Series A Preferred Stock [Member]Common Stock [Member]	Series A Preferred Stock [Member]Additional Paid-in Capital [Member]	Series A Preferred Stock [Member]Retained Earnings [Member]	Series A Preferred Stock [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2016																												59,432
Balance at Dec. 31, 2016																												$ 1	$ 256,629	$ (252,389)	$ 4,241
Employee stock-based compensation																													4,966		4,966
Issuance of common stock in August public offering, net of commissions and issuance costs																													3,589		3,589
Net and comprehensive loss																														(48,732)	(48,732)
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)																												23,452
Issuance of common stock (in shares)																												476
Issuance of common stock																													246		246
Balance (in shares) at Dec. 31, 2017																												83,359
Balance at Dec. 31, 2017																													265,636	(301,327)	(35,690)
Issuance of common stock under officers and directors purchase plan																													5		5
Stock Issued During Period, Shares, Employee Stock Purchase Plans																												209
Employee stock-based compensation																													2,027		2,027
Issuance of common stock in August public offering, net of commissions and issuance costs			$ 3,021		$ 3,021															$ 15,525	$ 15,525
Accretion of Series A Preferred Stock dividends																													(2,082)		(2,082)
Net and comprehensive loss																														(21,468)	(21,468)
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)		216,618																	17,979
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												209
Issuance of common stock to a vendor (in shares)																												8,000
Issuance of common stock to a vendor																													106		106
Exercises of warrants for common stock																													581		581
Conversion of convertible securities (in shares)						41,800					(16,278)	813,958
Conversion of convertible securities								$ 41,800		$ 41,800		$ 1	$ (1)
Issuance of common stock (in shares)																												4,220
Issuance of common stock																													337		337
Balance (in shares) at Sep. 30, 2018																											43,501	1,155,414
Balance at Sep. 30, 2018																												$ 1	326,949	(322,788)	4,162
Balance (in shares) at Dec. 31, 2017																												83,359
Balance at Dec. 31, 2017																													265,636	(301,327)	(35,690)
Issuance of common stock under officers and directors purchase plan																													21		21
Stock Issued During Period, Shares, Employee Stock Purchase Plans																												4,401
Employee stock-based compensation																													3,080		3,080
Issuance of common stock in August public offering, net of commissions and issuance costs		$ 2	$ 3,024		$ 3,026															$ 15,525	$ 15,525
Accretion of Series A Preferred Stock dividends																													(2,918)		(2,918)
Net and comprehensive loss																														(27,558)	(27,558)
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)		216,618																	17,979
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												4,401
Issuance of common stock to a vendor (in shares)																												8,000
Issuance of common stock to a vendor																													106		106
Exercises of warrants for common stock (in shares)																												29,050
Exercises of warrants for common stock																													581		581
Conversion of convertible securities (in shares)						41,800					(16,278)	813,915		(6,416)	1,604,000
Conversion of convertible securities								$ 42,794		$ 42,794		$ 8	(8)		$ 16	$ (16)
Balance (in shares) at Dec. 31, 2018																											45,671	3,492,200
Balance at Dec. 31, 2018																												$ 3	338,342	(328,885)	9,460
Balance (in shares) at Jun. 30, 2018																											43,501	930,587
Balance at Jun. 30, 2018																												$ 1	323,991	(317,400)	6,592
Issuance of common stock under officers and directors purchase plan																													5		5
Stock Issued During Period, Shares, Employee Stock Purchase Plans																												209
Employee stock-based compensation																													768		768
Issuance of common stock in August public offering, net of commissions and issuance costs																													3,021		3,021
Accretion of Series A Preferred Stock dividends																													(836)		(836)
Net and comprehensive loss																														(5,388)	(5,388)
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)																												216,618
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												209
Issuance of common stock to a vendor (in shares)																												8,000
Issuance of common stock to a vendor
Balance (in shares) at Sep. 30, 2018																											43,501	1,155,414
Balance at Sep. 30, 2018																												$ 1	326,949	(322,788)	4,162
Balance (in shares) at Dec. 31, 2018																											45,671	3,492,200
Balance at Dec. 31, 2018																												$ 3	338,342	(328,885)	9,460
Issuance of common stock under officers and directors purchase plan																													54		54
Stock Issued During Period, Shares, Employee Stock Purchase Plans																												18,735
Issuance of common stock upon vesting of restricted stock units (in shares)																												96,356
Issuance of common stock upon vesting of restricted stock units
Employee stock-based compensation																													1,532		1,532
Issuance of common stock in August public offering, net of commissions and issuance costs																												$ 4	3,807		3,811
Accretion of Series A Preferred Stock dividends																													(2,685)		(2,685)
Net and comprehensive loss																														(14,329)	(14,329)
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)																												3,813,559
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												18,735
Exercises of warrants for common stock (in shares)																												1,998,079
Exercises of warrants for common stock																												$ 2	7,991		7,993
Conversion of convertible securities (in shares)											(1,523)	380,750		(2,170)	542,500
Conversion of convertible securities															$ 1	$ (1)
Issuance of Series A Preferred stock to pay dividends (in shares)																						2,945
Issuance of Series A Preferred stock to pay dividends																								$ 2,918		$ 2,918
Balance (in shares) at Sep. 30, 2019																											44,923	10,342,179
Balance at Sep. 30, 2019																												$ 10	351,958	(343,214)	8,754
Balance (in shares) at Jun. 30, 2019																											44,923	6,421,317
Balance at Jun. 30, 2019																												$ 6	348,505	(338,591)	9,920
Issuance of common stock under officers and directors purchase plan																													18		18
Stock Issued During Period, Shares, Employee Stock Purchase Plans																												10,947
Issuance of common stock upon vesting of restricted stock units (in shares)																												96,356
Issuance of common stock upon vesting of restricted stock units
Employee stock-based compensation																													523		523
Issuance of common stock in August public offering, net of commissions and issuance costs																												$ 4	3,807		3,811
Accretion of Series A Preferred Stock dividends																													(895)		(895)
Net and comprehensive loss																														(4,623)	(4,623)
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												10,947
Balance (in shares) at Sep. 30, 2019																											44,923	10,342,179
Balance at Sep. 30, 2019																												$ 10	$ 351,958	$ (343,214)	$ 8,754

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities
Net loss	$ (14,329)	$ (21,468)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	654	735
Amortization of debt issuance costs and debt discount	129	87
Stock-based compensation	1,532	2,028
Noncash interest expense and other charges	1,146	5,330
Common stock to be issued for services		106
Provision for doubtful accounts receivable		45
Gain on sale of property and equipment		(28)
Provision for excess and obsolete inventories	80	630
Changes in operating assets and liabilities:
Accounts receivable	(147)	(378)
Other long-term assets	427	104
Inventories	(1,149)	776
Prepaid expenses and other current assets	(59)	(91)
Accounts payable	(229)	297
Accrued compensation	(8)	123
Leasehold liability	(984)
Accrued expenses and other current liabilities	(768)	(2,618)
Other long-term liabilities and accrued interest	(32)	(115)
Net cash used in operating activities	(13,737)	(14,437)
Cash flows from investing activities
Purchases of property and equipment	(88)	(411)
Proceeds from sale of property and equipment	18	28
Net cash used in investing activities	(70)	(383)
Cash flows from financing activities
Proceeds from the issuance of convertible preferred stock, net of issuance costs		15,534
Proceeds from the issuance of common stock related to warrant exercises	7,993	581
Proceeds from the issuance of common stock in public offerings, net of issuance costs	3,811	3,539
Proceeds from the issuance of common stock under officers and directors purchase plan	54
Payment of debt discount in connection with loan amendment		(155)
Payment of accrued interest		(60)
Net cash provided by financing activities	11,858	19,439
Net change in cash and cash equivalents	(1,949)	4,619
Cash and cash equivalents, beginning of period	16,410	5,389
Cash and cash equivalents, end of period	14,461	10,008
Supplemental disclosure of cash flow information
Cash paid for interest		60
Noncash investing and financing activities:
Conversion of CRG loan principal into Series A Preferred Stock		38,000
Accretion of Series A Preferred Stock dividends	2,685	2,082
Issuance of Series A Preferred Stock as dividend payment	2,918
Reclassification of right of use asset to prepaid rent	358
Increase to right of use asset and leasehold liability arising from lease amendment	4,680
Transfers between inventory and property and equipment	380	103
Deemed dividend arising from beneficial conversion feature of convertible preferred stock		$ 5,216

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 14,461		$ 16,410	$ 10,008		$ 5,389	$ 36,096
Accounts receivable, net of allowance for doubtful accounts of $185 and $260 at September 30, 2019 and December 31, 2018, respectively	1,301		1,154			1,127
Inventories	4,112		3,422			4,295
Prepaid expenses and other current assets	489		635			640
Total current assets	20,363		21,621			11,451
Property and equipment, net	1,873		2,078			2,950
Other assets	579					687
Total assets	28,007		23,699			15,088
Current liabilities:
Accounts payable	919		1,148			1,273
Accrued compensation	1,189		1,197			863
Series A Preferred stock dividends payable	2,685		2,918
Accrued expenses and other current liabilities	681		1,449			3,597
Borrowings	8,578		7,486			44,744
Total current liabilities	14,907		14,198			50,477
Other long-term liabilities	9		41			301
Total liabilities	19,253		14,239			50,778
Commitments and contingencies (Note 6)
Stockholders’ equity:
Convertible preferred stock issuable in series, par value of $0.001 Shares authorized: 5,000,000 at June 30, 2019 and December 31, 2018 Shares issued and outstanding: 44,923 and 45,671 at June 30, 2019 and December 31, 2018, respectively; aggregate liquidation preference of $46,535 and $44,718 at June 30, 2019 and December 31, 2018, respectively
Common stock, par value of $0.001; Shares authorized: 100,000,000 at September 30, 2019 and December 31, 2018; Shares issued and outstanding: 10,342,179 and 3,492,200 at September 30, 2019 and December 31, 2018, respectively	10		3			1
Additional paid-in capital	351,958		338,342			265,636
Accumulated deficit	(343,214)		(328,885)			(301,327)
Total stockholders’ equity (deficit)	8,754	$ 9,920	9,460	$ 4,162	$ 6,592	(35,690)	$ 4,241
Total liabilities and stockholders’ equity (deficit)	$ 28,007		$ 23,699			$ 15,088

Balance Sheets (Parentheticals)

Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Feb. 16, 2018	Dec. 31, 2017
Allowance for doubtful accounts	$ 185	$ 260		$ 146
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000		5,000,000
Preferred stock, shares issued (in shares)	44,923	45,671		0
Preferred stock, shares outstanding (in shares)	44,923	45,671		0
Preferred stock, liquidation value	$ 47,430	$ 44,718		$ 0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001		$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000		100,000,000
Common stock, shares issued (in shares)	10,342,179	3,492,200		83,360
Common stock, shares outstanding (in shares)	10,342,179	3,492,200		83,360

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Revenues	$ 2,410	$ 2,020	$ 6,569	$ 5,887	$ 7,915	$ 9,934
Cost of revenues	1,563	1,477	4,629	5,061	6,531	13,002
Gross profit (loss)	847	543	1,940	826	1,384	(3,068)
Operating expenses:
Research and development	1,371	1,404	4,120	4,340	6,009	11,319
Selling, general and administrative	4,091	4,499	12,168	13,443	17,442	25,120
Restructuring charges						1,285
Litigation settlement						1,760
Total operating expenses	5,462	5,903	16,288	17,783	23,451	39,484
Loss from operations	(4,615)	(5,360)	(14,348)	(16,957)	(22,067)	(42,552)
Interest income	70	54	242	137	214	108
Interest expense	(377)	(324)	(1,091)	(5,358)	(5,692)	(6,299)
Other income net	299	242	868	710	(13)	11
Net loss and comprehensive loss	(4,623)	(5,388)	(14,329)	(21,468)	(27,558)	(48,732)
Accretion of preferred stock dividends	(895)	(836)	(2,685)	(2,082)	(2,918)
Deemed dividend arising from beneficial conversion feature of convertible preferred stock				(5,216)	(5,216)
Net loss applicable to common stockholders	$ (5,518)	$ (6,224)	$ (17,014)	$ (28,766)	$ (35,692)	$ (48,732)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.70)	$ (5.56)	$ (2.75)	$ (43)	$ (33.42)	$ (749.72)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	7,900	1,119	6,189	669	1,068	65

Statements of Stockholders' Equ

Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]Preferred Stock [Member]	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]Common Stock [Member]	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]Additional Paid-in Capital [Member]	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]Retained Earnings [Member]	Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]	November Public Offering [Member]Preferred Stock [Member]	November Public Offering [Member]Common Stock [Member]	November Public Offering [Member]Additional Paid-in Capital [Member]	November Public Offering [Member]Retained Earnings [Member]	November Public Offering [Member]	Series B Preferred Stock [Member]Preferred Stock [Member]	Series B Preferred Stock [Member]Additional Paid-in Capital [Member]	Series B Preferred Stock [Member]	Conversion of Series B Preferred Stock into Common Stock [Member]Preferred Stock [Member]	Conversion of Series B Preferred Stock into Common Stock [Member]Common Stock [Member]	Conversion of Series B Preferred Stock into Common Stock [Member]Additional Paid-in Capital [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]Preferred Stock [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]Common Stock [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]Additional Paid-in Capital [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]Retained Earnings [Member]	Conversion of Series C Preferred Stock into Common Stock [Member]	Conversion of CRG into Series A Preferred Stock [Member]Preferred Stock [Member]	Conversion of CRG into Series A Preferred Stock [Member]Common Stock [Member]	Conversion of CRG into Series A Preferred Stock [Member]Additional Paid-in Capital [Member]	Conversion of CRG into Series A Preferred Stock [Member]Retained Earnings [Member]	Conversion of CRG into Series A Preferred Stock [Member]	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2016																												59,432
Balance at Dec. 31, 2016																												$ 1	$ 256,629	$ (252,389)	$ 4,241
Issuance of common stock (in shares)																												476
Issuance of common stock																													246		246
Employee stock-based compensation																													4,966		4,966
Adjustment for change in accounting treatment of stock-based compensation regarding forfeitures on a modified retrospective basis																													206	(206)
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)																												23,452
Issuance of common stock in August public offering, net of commissions and issuance costs																													3,589		3,589
Net and comprehensive loss																														(48,732)	(48,732)
Balance (in shares) at Dec. 31, 2017																												83,359
Balance at Dec. 31, 2017																													265,636	(301,327)	(35,690)
Issuance of common stock (in shares)																												4,220
Issuance of common stock																													337		337
Employee stock-based compensation																													2,027		2,027
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)		216,618									17,979
Issuance of common stock in August public offering, net of commissions and issuance costs			$ 3,021		$ 3,021							$ 15,525	$ 15,525
Net and comprehensive loss																														(21,468)	(21,468)
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												209
Issuance of common stock under officers and directors purchase plan																													5		5
Exercises of warrants for common stock																													581		581
Issuance of common stock to a vendor (in shares)																												8,000
Issuance of common stock to a vendor																													106		106
Conversion of convertible securities (in shares)														(16,278)	813,958							41,800
Conversion of convertible securities															$ 1	$ (1)								$ 41,800		$ 41,800
Accretion of Series A Preferred Stock dividends																													(2,082)		(2,082)
Balance (in shares) at Sep. 30, 2018																											43,501	1,155,414
Balance at Sep. 30, 2018																												$ 1	326,949	(322,788)	4,162
Balance (in shares) at Dec. 31, 2017																												83,359
Balance at Dec. 31, 2017																													265,636	(301,327)	(35,690)
Employee stock-based compensation																													3,080		3,080
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)		216,618				8,586	728,500				17,979
Issuance of common stock in August public offering, net of commissions and issuance costs		$ 2	$ 3,024		$ 3,026		$ 7	$ 10,172		$ 10,179		$ 15,525	$ 15,525
Net and comprehensive loss																														(27,558)	(27,558)
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												4,401
Issuance of common stock under officers and directors purchase plan																													21		21
Exercises of warrants for common stock (in shares)																												29,050
Exercises of warrants for common stock																													581		581
Issuance of common stock to a vendor (in shares)																												8,000
Issuance of common stock to a vendor																													106		106
Conversion of convertible securities (in shares)														(16,278)	813,915		(6,416)	1,604,000				41,800
Conversion of convertible securities															$ 8	(8)		$ 16	$ (16)					$ 42,794		$ 42,794
Issuance of common stock to Lincoln Park (in shares)																												4,356
Issuance of common stock to Lincoln Park																													314		314
Accretion of Series A Preferred Stock dividends																													(2,918)		(2,918)
Balance (in shares) at Dec. 31, 2018																											45,671	3,492,200
Balance at Dec. 31, 2018																												$ 3	338,342	(328,885)	9,460
Balance (in shares) at Jun. 30, 2018																											43,501	930,587
Balance at Jun. 30, 2018																												$ 1	323,991	(317,400)	6,592
Employee stock-based compensation																													768		768
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)																												216,618
Issuance of common stock in August public offering, net of commissions and issuance costs																													3,021		3,021
Net and comprehensive loss																														(5,388)	(5,388)
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												209
Issuance of common stock under officers and directors purchase plan																													5		5
Issuance of common stock to a vendor (in shares)																												8,000
Issuance of common stock to a vendor
Accretion of Series A Preferred Stock dividends																													(836)		(836)
Balance (in shares) at Sep. 30, 2018																											43,501	1,155,414
Balance at Sep. 30, 2018																												$ 1	326,949	(322,788)	4,162
Balance (in shares) at Dec. 31, 2018																											45,671	3,492,200
Balance at Dec. 31, 2018																												$ 3	338,342	(328,885)	9,460
Employee stock-based compensation																													1,532		1,532
Issuance of common stock in July public offering, net of commissions and issuance costs (in shares)																												3,813,559
Issuance of common stock in August public offering, net of commissions and issuance costs																												$ 4	3,807		3,811
Net and comprehensive loss																														(14,329)	(14,329)
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												18,735
Issuance of common stock under officers and directors purchase plan																													54		54
Exercises of warrants for common stock (in shares)																												1,998,079
Exercises of warrants for common stock																												$ 2	7,991		7,993
Conversion of convertible securities (in shares)														(1,523)	380,750		(2,170)	542,500
Conversion of convertible securities																		$ 1	$ (1)
Accretion of Series A Preferred Stock dividends																													(2,685)		(2,685)
Balance (in shares) at Sep. 30, 2019																											44,923	10,342,179
Balance at Sep. 30, 2019																												$ 10	351,958	(343,214)	8,754
Balance (in shares) at Jun. 30, 2019																											44,923	6,421,317
Balance at Jun. 30, 2019																												$ 6	348,505	(338,591)	9,920
Employee stock-based compensation																													523		523
Issuance of common stock in August public offering, net of commissions and issuance costs																												$ 4	3,807		3,811
Net and comprehensive loss																														(4,623)	(4,623)
Issuance of common stock under officers’ and directors’ purchase plan (in shares)																												10,947
Issuance of common stock under officers and directors purchase plan																													18		18
Accretion of Series A Preferred Stock dividends																													(895)		(895)
Balance (in shares) at Sep. 30, 2019																											44,923	10,342,179
Balance at Sep. 30, 2019																												$ 10	$ 351,958	$ (343,214)	$ 8,754

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities
Net loss	$ (27,558)	$ (48,732)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,281	1,476
Amortization of debt issuance costs and debt discount	117	218
Stock-based compensation	3,080	4,966
Noncash interest expense and other charges	5,634	3,252
Common stock to be issued for services	106
Gain on sale of property and equipment	(7)	18
Provision for litigation settlement		1,760
Provision for doubtful accounts receivable	133	125
Provision for excess and obsolete inventories	914	5,500
Changes in operating assets and liabilities:
Accounts receivable	(160)	2,318
Inventories	(92)	(1,181)
Prepaid expenses and other current assets	5	22
Other long-term assets	340	(475)
Accounts payable	(125)	(334)
Accrued compensation	334	(1,945)
Accrued expenses and other current liabilities and accrued interest	(2,208)	(1,205)
Other long-term liabilities	(260)	(259)
Net cash used in operating activities	(18,466)	(34,476)
Cash flows from investing activities
Purchases of property and equipment	(32)	(45)
Proceeds from sale of property and equipment	28	4
Net cash used in investing activities	(4)	(41)
Cash flows from financing activities
Proceeds from the issuance of convertible preferred stock, net of issuance costs	15,525
Proceeds from the issuance of common stock in public offerings, net of issuance costs	10,179
Proceeds from the issuance of common stock under officers and directors purchase plan	21
Principal paydown of capital lease obligations		(25)
Proceeds from public offerings, net of issuance costs	3,026	3,589
Proceeds from the issuance of common stock related to warrant exercises	581
Payment of debt discount in connection with loan amendment	(155)
Proceeds from the issuance of common stock	314	246
Net cash provided by financing activities	29,491	3,810
Net change in cash and cash equivalents	11,021	(30,707)
Cash and cash equivalents, beginning of period	5,389	36,096
Cash and cash equivalents, end of period	16,410	5,389
Supplemental disclosure of cash flow information
Cash paid for interest	60	3,942
Noncash investing and financing activities:
Conversion of CRG loan principal into Series A Preferred Stock	42,794
Disposal of fully depreciated property and equipment	2,849	1,738
Accretion of Series A Preferred Stock dividends	2,918
Transfers between inventory and property and equipment	$ 51	$ 153

Note 1 - Organization

Note 1 - Organization	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Nature of Operations [Text Block]	1. Organization, Nature of Business Avinger, Inc. (the “Company”), a Delaware corporation, was incorporated in March 2007. “OCT”) March 2016, 510 May 2018, 510 April 2019, August 2019. Liquidity Matters The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) No. 2014 15, Presentation of Financial Statements - Going Concern (Subtopic 205 40 one In the course of its activities, the Company has incurred losses and negative cash flows from operations since its inception. As of September 30, 2019, $343.2 $14.5 September 30, 2019 second 2020. $3.8 August 2019 $10.2 November 2018 $3.0 July 2018 $15.5 February 2018 nine September 30, 2019 $8.0 twelve may no not twelve no may one not Additionally, due to the substantial doubt about the Company’s ability to continue operating as a going concern and the material adverse change clause in the Loan Agreement with CRG, the entire amount of borrowings at September 30, 2019 December 31, 2018 not Public Offerings On February 16, 2018, 17,979 1,797,900 $15.5 $0.001 no no not one 1 seventh 50 one 2 seventh 60th 50 60 seven April 2019, 60 60 2 seventh 41,800 $38.0 $41.8 2,090,000 On July 12, 2018, 216,618 $16.425 one two 108,309 July 16, 2018, $3.0 $15.80 July 16, 2021. On November 1, 2018, 728,500 8,586 $10.2 $0.001 no On August 26, 2019, 3,813,559 $1.18 $3.8 February 2018 $1.18	1. Organization, Nature of Business Avinger, Inc. (the “Company”), a Delaware corporation, was incorporated in March 2007. “OCT”) March 2016, 510 May 2018, 510 510 August 2018 October 2018. Liquidity Matters The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) No. 2014 15, 205 40 one December 31, 2018, $328.9 $16.4 December 31, 2018 fourth 2019. $10.2 November 2018 $15.5 February 2018 $3.0 July 2018 twelve may no not twelve no may one not December 31, 2018 2017 not Public Offerings On February 3, 2016, $150,000,000 may, $50,000,000. September 2015. March 8, 2016. December 31, 2017, 18,968 $176.80 $3,187,000, $101,000 December 31, 2016, 2,737 $1,947.40 $5,171,000, $160,000 $75 one third twelve On February 16, 2018, 17,979 17,979,000 $15.5 one seventh 500 1 one seventh 60th 500 60 seven 2 41,800 $38.0 $41.8 2,090,000 On July 12, 2018, 216,618 $16.425 one two 108,309 July 16, 2018, $3.0 February 2018 $15.80 $15.80 may January 17, 2019 July 16, 2021. On November 1, 2018, 728,500 8,586 $10.2 $0.001 no

Note 2 - Summary of Significant

Note 2 - Summary of Significant Accounting Policies 1	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Basis of Presentation and Significant Accounting Policies [Text Block]	2. Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and pursuant to the rules and regulations of the SEC. The accompanying unaudited condensed interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the Company’s financial information. The results for the three nine September 30, 2019 not December 31, 2019, December 31, 2018 10 December 31, 2018, March 6, 2019. 2 10 December 31, 2018. On January 30, 2018, 1 40 June 19, 2019 , 1 - 10 June 21, 2019. not Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its common stock valuation and related stock-based compensation, the valuation of the common stock warrants, the valuation of compound embedded derivatives, provisions for doubtful accounts receivable and excess and obsolete inventories, clinical trial accruals, and its reserves for sales returns and warranty costs. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not may may Fair Value of Financial Instruments The Company has evaluated the estimated fair value of its financial instruments as of September 30, 2019 December 31, 2018. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three 1 September 30, 2019 December 31, 2018, no September 30, 2019 December 31, 2018. Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable to the extent of the amounts recorded on the balance sheets. The Company’s policy is to invest in cash and cash equivalents, consisting of money market funds. These financial instruments are held in Company accounts at one The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at September 30, 2019 December 31, 2018. The Company’s accounts receivable are due from a variety of healthcare organizations in the United States and select international markets. At September 30, 2019 December 31, 2018, no 10% three nine September 30, 2019 2018, no 10% The Company manufactures its commercial products in-house, including Pantheris and the Ocelot family of catheters. Certain of the Company’s product components and sub-assemblies continue to be manufactured by sole suppliers. Disruption in component or sub-assembly supply from these manufacturers or from in-house production would have a negative impact on the Company’s financial position and results of operations. The Company is subject to certain risks, including that its devices may not no not third Existing or future devices developed by the Company may may may Revenue Recognition The Company’s revenues are derived from ( 1 2 3 1. Lightbox sales: The Company sells its products directly to hospitals and medical centers. Provided all other criteria for revenue recognition have been met, the Company recognizes revenue for Lightbox sales directly to end customers when delivery and acceptance occurs, which is defined as receipt by the Company of an executed form by the customer acknowledging that the training and installation process is complete. 2. Sales of disposables: Disposable revenues consist of sales of the Company’s catheters and accessories and are recognized when the product has shipped, risk of loss and title has passed to the customer and collectability is reasonably assured. 3. Service revenue: Service contract revenue is recognized ratably over the term of the service period and maintenance contract revenue is recognized as work is performed. To date, service revenue has been insignificant. The Company offers its customers the ability to purchase or lease its Lightbox. In addition, the Company provides a Lightbox under a limited commercial evaluation program to allow certain strategic accounts to install and utilize the Lightbox for a limited trial period of three six The Company evaluates its lease and commercial evaluation program agreements and accounts for these contracts under the guidance in Accounting Standards Codification (“ASC”) 840, Leases No. 2014 09, Revenue from Contracts with Customers (Topic 606 third The Company assessed whether the embedded lease is an operating lease or sales-type lease. Based on the Company’s assessment of the guidance and given that any payments under the lease agreements are dependent upon contingent future sales, it was determined that collectability of the minimum lease payments is not not For sales through distributors, the Company recognizes revenue when title to the product and the risk of loss transfers from the Company to the distributor. The distributors are responsible for all marketing, sales, training and warranty in their respective territories. The standard terms and conditions contained in the Company’s distribution agreements do not not The Company estimates reductions in revenue for potential returns of products by customers. In making such estimates, management analyzes historical returns, current economic trends and changes in customer demand and acceptance of its products. The Company expenses shipping and handling costs as incurred and includes them in the cost of revenues. When the Company bills shipping and handling costs to customers, such amounts billed are included as a component of revenue. Cost of Revenues Cost of revenues consists primarily of manufacturing overhead costs, material costs and direct labor. A significant portion of the Company’s cost of revenues currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of revenues also includes depreciation expense for the Lightboxes under lease agreements and certain direct costs such as shipping costs. Product Warranty Costs The Company typically offers a one Balance at December 31, 2018 $ 272 Warranty provision 70 Usage/release (128 ) Balance at September 30, 2019 $ 214 Net Loss per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Any common stock shares subject to repurchase are excluded from the calculations as the continued vesting of such shares is contingent upon the holders’ continued service to the Company. As of September 30, 2019 December 31, 2018, no Net loss per share attributable to common stockholders was determined as follows (in thousands, except per share data): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net loss attributable to common stockholders $ (5,518 ) $ (6,224 ) $ (17,014 ) $ (28,766 ) Weighted average common stock outstanding 7,900 1,119 6,189 669 Net loss per share attributable to common stockholders, basic and diluted $ (0.70 ) $ (5.56 ) $ (2.75 ) $ (43.00 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an anti-dilutive impact due to losses reported: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Common stock warrant equivalents 2,757,741 1,867,226 3,346,568 1,511,832 Common stock options 7,444 8,472 7,596 7,246 Convertible preferred stock 44,923 4,450 45,046 3,969 Unvested restricted stock units 371,651 84,848 316,575 374 3,181,759 1,964,996 3,715,785 1,523,421 Segment and Geographical Information The Company operates and manages its business as one three September 30, 2019 2018, 96% 94%, nine September 30, 2019 2018, 94% 94%, Recent Accounting Pronouncements Adopted: In May 2014, No. 2014 09 , Revenue from Contracts with Customers (Topic 606 605, Revenue Recognition August 2015, No. 2015 14, Revenue from Contracts with Customers (Topic 606 one December 15, 2017. In March 2016, No. 2016 08, Revenue from Contracts with Customers (Topic 606 ) In April 2016, No. 2016 10, Revenue from Contracts with Customers (Topic 606 ) Identifying Performance Obligations and Licensing In May 2016, No. 2016 12, Revenue from Contracts with Customers (Topic 606 ) Narrow-Scope Improvements and Practical Expedients The Company adopted ASC 606 January 1, 2018, not In May 2017, No. 2017 09, Compensation—Stock Compensation (Topic 718 ) 718. January 1, 2018 not In August 2016, No. 2016 15, Statement of Cash Flows (Topic 230 ): Classification of Certain Cash Receipts and Cash Payments December 15, 2017, January 1, 2018 not In February 2016, No. 2016 02, Leases (Topic 842 ). 842 one July, 842 No. 2018 10, Codification Improvements to Topic 842, Leases No. 2018 11, Leases (Topic 842 ): Targeted Improvements first 2019 January 1, 2019. $1.8 no $240,000 $720,000 three nine September 30, 2018 In June 2018, No. 2018 07, Compensation-Stock Compensation (Topic 718 ): Improvements to Nonemployee Share-Based Payment Accounting, 718 718 not 1 2 606. December 15, 2018, no 606. July 1, 2018 not	2. Basis of Presentation The accompanying financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and pursuant to the rules and regulations of the SEC (“SEC”). On January 30, 2018, 1 40 not January 30, 2018. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its common stock valuation and related stock-based compensation, the valuation of the common stock warrants, the valuation of compound embedded derivatives, provisions for doubtful accounts receivable and excess and obsolete inventories, clinical trial accruals, and its reserves for sales returns and warranty costs. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not may may Fair Value of Financial Instruments The Company has evaluated the estimated fair value of its financial instruments as of December 31, 2018 2017. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three December 31, 2018 2017, no December 31, 2018 2017. Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable to the extent of the amounts recorded on the balance sheets. The Company’s policy is to invest in cash and cash equivalents, consisting of money market funds. These financial instruments are held in Company accounts at one The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at December 31, 2018 2017. The Company’s accounts receivable are due from a variety of healthcare organizations in the United States and select international markets. At December 31, 2018 2017, no 10% December 31, 2018 2017, no 10% The Company manufactures its commercial products in-house, including Pantheris and the Ocelot family of catheters. Certain of the Company’s product components and sub-assemblies continue to be manufactured by sole suppliers. Disruption in component or sub-assembly supply from these manufacturers or from in-house production would have a negative impact on the Company’s financial position and results of operations. The Company is subject to certain risks, including that its devices may not no not third Existing or future devices developed by the Company may may may Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not not Inventories Inventories are valued at the lower of cost or net realizable value. Cost is determined using the first first may Property and Equipment Property and equipment are recorded at cost. Repairs and maintenance costs are expensed as incurred. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets of three five Deferred Offering Costs Deferred offering costs, which primarily consist of direct incremental legal and accounting fees relating to the Company’s offerings of equity securities to Lincoln Park, were capitalized. The deferred offering costs were be offset against proceeds from the public offering upon the effectiveness of the public offerings in fiscal 2018. December 31, 2018 2017, zero $464,000 2018 Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not not December 31, 2018. Revenue Recognition The Company’s revenues are derived from ( 1 2 3 605 10, The Company’s revenue recognition policies generally result in revenue recognition at the following points: 1. Lightbox sales: The Company sells its products directly to hospitals and medical centers. Provided all other criteria for revenue recognition have been met, the Company recognizes revenue for Lightbox sales directly to end customers when delivery and acceptance occurs, which is defined as receipt by the Company of an executed form by the customer acknowledging that the training and installation process is complete. 2. Sales of disposables: Disposable revenues consist of sales of the Company’s catheters and accessories and are recognized when the product has shipped, risk of loss and title has passed to the customer and collectability is reasonably assured. 3. Service revenue: Service revenue is recognized ratably over the term of the service period. To date service revenue has been insignificant. The Company offers its customers the ability to purchase or lease its Lightbox. In addition, the Company provides a Lightbox under a limited commercial evaluation program to allow certain strategic accounts to install and utilize the Lightbox for a limited trial period of three six The Company assessed whether the embedded lease is an operating lease or sales-type lease. Based on the Company’s assessment of the guidance and given that any payments under the lease agreements are dependent upon contingent future sales, it was determined that collectability of the minimum lease payments is not not For sales through distributors, the Company recognizes revenue when title to the product and the risk of loss transfers from the Company to the distributor. The distributors are responsible for all marketing, sales, training and warranty in their respective territories. The standard terms and conditions contained in the Company’s distribution agreements do not not The Company estimates reductions in revenue for potential returns of products by customers. In making such estimates, management analyzes historical returns, current economic trends and changes in customer demand and acceptance of its products. The Company expenses shipping and handling costs as incurred and includes them in the cost of revenues. In those cases where the Company bills shipping and handling costs to customers, it will classify the amounts billed as a component of revenue. Cost of Revenues Cost of revenues consists primarily of manufacturing overhead costs, material costs and direct labor. A significant portion of the Company’s cost of revenues currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of revenues also includes depreciation expense for the Lightboxes under lease agreements, product warranty costs, product written-off due to obsolescence, and certain direct costs such as shipping costs. Product Warranty Costs The Company typically offers a one Year Ended December 31, 2018 2017 Balance, beginning of year $ 390 $ 509 Warranty provision 333 306 Usage/Release (451 ) (425 ) Balance, end of year $ 272 $ 390 Research and Development The Company expenses research and development costs as incurred. Research and development expenses include personnel and personnel-related costs, costs associated with pre-clinical and clinical development activities, and costs for prototype products that are manufactured prior to market approval for that prototype product; internal and external costs associated with the Company’s regulatory compliance and quality assurance functions, including the costs of outside consultants and contractors that assist in the process of submitting and maintaining regulatory filings, and overhead costs, including allocated facility and related expenses. Clinical Trials The Company accrues and expenses costs for its clinical trial activities performed by third Common Stock Valuation and Stock-Based Compensation Stock-based compensation for the Company includes amortization related to all stock options, restricted stock units (“RSUs”) and shares issued under the employee stock purchase plan (“ESPP”), based on the grant-date estimated fair value. The fair value of stock options is estimated on the date of grant using the Black-Scholes option pricing model and recognized as expense on a straight-line basis over the vesting period of the award. The Company measures the fair value of RSUs using the closing stock price of a share of the Company’s common stock on the grant date and is recognized as expense on a straight-line basis over the vesting period of the award. Because noncash stock-based compensation expense is based on awards ultimately expected to vest, it is reduced by an estimate for future forfeitures. The Company estimates a forfeiture rate for its stock options and RSUs based on an analysis of its actual forfeiture experience and other factors. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates. Prior to the Company’s IPO in January 2015, third Foreign Currency The Company records net gains and losses resulting from foreign exchange transactions as a component of foreign currency exchange losses in other income (expense), net. During the years ended December 31, 2018 2017, $13,000 $11,000 Income Taxes The Company utilizes the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to record interest and penalties on uncertain tax positions as income tax expense when they occur. During the years ended December 31, 2018 2017, not Net Loss per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholder by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Any common stock shares subject to repurchase are excluded from the calculations as the continued vesting of such shares is contingent upon the holders’ continued service to the Company. As of December 31, 2018 2017, no Net loss per share attributable to common stockholders was determined as follows (in thousands, except per share data): Year Ended December 31, 2018 2017 Net loss attributable to common stockholders $ (35,692 ) $ (48,732 ) Weighted average common stock outstanding 1,068 65 Net loss per share attributable to common stockholders, basic and diluted $ (33.42 ) $ 749.72 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an antidilutive impact due to losses reported: Year Ended December 31, 2018 2017 Common stock options 7,179 7,664 Convertible preferred stock 41,398 - Unvested restricted stock units 92,245 508 Common stock warrants 2,077,871 5,371 2,218,693 13,543 Comprehensive Loss For the years ended December 31, 2018 2017, no Segment and Geographical Information The Company operates and manages its business as one December 31, 2018 2017, 94% 95%, Recent Accounting Pronouncements Adopted: In May 2014, No. 2014 09, “ 606 ” 605, August 2015, No. 2015 14, 606 one December 15, 2017. In March 2016, No. 2016 08, 606 In April 2016, No. 2016 10, 606 In May 2016, No. 2016 12, 606 The Company adopted ASC 606 January 1, 2018, not In May 2017, No. 2017 09, 718 718. January 1, 2018 not In August 2016, No. 2016 15, 230 December 15, 2017, January 1, 2018 not In November 2016, No. 2016 18, 230 2016 18 2016 18 December 15, 2017. January 1, 2018 not Pending Adoption: In February 2016, No. 2016 02 842 842 one July, 842 No. 2018 10, 842 , No. 2018 11, 842 first 2019 The Company has evaluated the impact of the adoption of these standards on January 1, 2019, $1.8 no In June 2018, No. 2018 07, 718 718 718 not 1 2 606. December 15, 2018, no 606. January 1, 2019 not

Note 3 - Fair Value Measurement

Note 3 - Fair Value Measurements	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Fair Value Disclosures [Text Block]	3. The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three Level 1—Quoted Level 2—Inputs 1 not Level 3—Unobservable no As of September 30, 2019 December 31, 2018, 1 September 30, 2019 December 31, 2018, no 2 3. no three nine September 30, 2019 2018.	3. The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three Level 1—Quoted Level 2—Inputs 1 not Level 3—Unobservable no As of December 31, 2018 2017, 1 December 31, 2018 2017, no 2. December 31, 2018, 3.. December 31, 2017, no 3. no December 31, 2018 2017.

Note 4 - Inventories 1

Note 4 - Inventories 1	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Inventory Disclosure [Text Block]	4. Inventories consisted of the following (in thousands): September 30, December 31, 2019 2018 Raw materials $ 1,898 $ 2,102 Work-in-process 544 158 Finished products 1,670 1,162 Total inventories $ 4,112 $ 3,422	4. Inventories consisted of the following (in thousands): December 31, 2018 2017 Raw materials $ 1,162 $ 1,286 Work-in-process 158 - Finished products 2,102 3,009 Total inventories $ 3,422 $ 4,295

Note 5 - Borrowings

Note 5 - Borrowings	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Debt Disclosure [Text Block]	5. CRG On September 22, 2015, $50,000,000 March 29, 2017. $30,000,000 September 22, 2015. $10,000,000 June 15, 2016 On February 14, 2018, $38,000,000 $3,800,000 7, Under the Loan Agreement, as amended, no first 2020. first 2020 not 12.5%. third 2021, $1.2 $2.4 2021, $4.8 2022 $2.4 2023. The Company may 5.0% 1.0% no fifth 1.5% 7.0% The Loan Agreement requires that the Company adheres to certain affirmative and negative covenants, including financial reporting requirements, certain minimum financial covenants for pre-specified liquidity and revenue requirements and a prohibition against the incurrence of indebtedness, or creation of additional liens, other than as specifically permitted by the terms of the Loan Agreement. In particular, the covenants of the original Loan Agreement included a covenant that the Company maintain a minimum of $5,000,000 2.0 may On February 14, 2018, No. 2 ● extend the interest only payment period and the period during which the Company may June 30, 2021; ● provide for a 15% ● permit the Company to make the entire interest payment for payment dates in 2018 2019 no ● extend the maturity date to June 30, 2023; ● modify certain of the covenants, including the indebtedness covenant, lien covenant and restricted payments covenant, to eliminate or modify permitted exceptions to the restrictions in those covenants; ● modify the financial covenants to reduce the minimum liquidity requirement to $3,500,000 2018 2019, $15,000,000 2020, $20,000,000 2021 $25,000,000 2022; ● provide CRG with board observer rights. As of September 30, 2019, As of September 30, 2019, Year Ending December 31, 2019 (remaining three months of the year) $ — 2020 799 2021 3,403 2022 5,522 2023 3,981 13,705 Less: Amount of PIK additions and final facility fee to be accreted subsequent to September 30, 2019 (4,497 ) Less: Amount representing debt financing costs (630 ) Borrowings, as of September 30, 2019 $ 8,578 In connection with drawdowns under the Loan Agreement, the Company recorded aggregate debt discounts of $1.3 September 30, 2019 December 31, 2018, $630,000 $757,000, $42,000 $30,000 three September 30, 2019 2018, $127,000 $84,000 nine September 30, 2019 2018, three September 30, 2019 2018, $377,000 $362,000, nine $1.1 $5.4 Due to the substantial doubt about the Company’s ability to continue operating as a going concern and the material adverse change clause in the Loan Agreement with CRG, the entire amount of borrowings at September 30, 2019 December 31, 2018 not	7. CRG On September 22, 2015, $50,000,000 March 29, 2017. $30,000,000 September 22, 2015. $10,000,000 June 15, 2016 $10,000,000, March 29, 2017, not On October 28, 2016, 2016 $18,000,000. February 14, 2018, $38,000,000 $3,800,000 7, December 31, 2018, $3,800,000 Under the Loan Agreement, as in effect prior to amendment, the first sixteen eight 12.5% September 30, 2015. 12.5% 8.5% 4.0% eight two September 30, 2021. The Company may 5.0% 1.0% no fifth 1.5% 7.0% $5,000,000 $7,000,000 2015, $23,000,000 2016, $40,000,000 2017, $50,000,000 2018, $60,000,000 2019 $70,000,000 2020 2.0 may On January 24, 2018, $5,000,0000 $2,500,000 January 1, 2018 February 28, 2018, $5,000,000 On February 14, 2018, No. 2 ● extend the interest only payment period and the period during which the Company may June 30, 2021; ● provide for a 15% ● permit the Company to make the entire interest payment for payment dates in 2018 2019 no ● extend the maturity date to June 30, 2023; ● modify certain of the covenants, including the indebtedness covenant, lien covenant and restricted payments covenant, to eliminate or modify permitted exceptions to the restrictions in those covenants; ● modify the financial covenants to reduce the minimum liquidity requirement to $3,500,000 2018 2019, $15,000,000 2020, $20,000,000 2021 $25,000,000 2022; ● provide CRG with board observer rights. As of December 31, 2018, As of December 31, 2018, Principal and PIK Period Ending December 31, Loan Repayments 2019 $ — 2020 — 2021 — 2022 — 2023 and after 2,000 2,000 Add: PIK 6,243 8,243 Less: Amount representing debt financing costs (757 ) Borrowings, as of December 31, 2018 $ 7,486 Contemporaneously with the execution of the Loan Agreement in September 2015, $5,000,000 870 September 22, 2015 $5,596.40 10 September 21, 2015. September 22, 2015 $5,588.00 $8.40 In connection with the initial drawdown under the Loan Agreement, the Company recorded a debt discount of $876,000 $450,000, $541,000 $115,000 June 2016 February 2018, $275,000 $150,000, $125,000. No.2 February 2018, $154,000 December 31, 2018 2017, $757,000 $716,000, $117,000 $203,000 December 31, 2018 2017, As noted in Note 1 December 31, 2018 2017 not

Note 6 - Commitments and Contin

Note 6 - Commitments and Contingencies	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	6. Lease Commitments The Company’s operating lease obligations primarily consist of leased office, laboratory, and manufacturing space under a non-cancelable operating lease that originally were to expire in November 2019. $369,000 On October 19, 2017, one December 1, 2017 November 15, 2019 15 $82,410 Upon the adoption of Topic 842 January 1, 2019, $1.8 On April 1, 2019, five November 30, 2019. November 30, 2024. $5.8 November 2024, December 1, 2019. not In connection with the amendment the Company adjusted its right-of-use asset and lease liability to $6.0 6.5% not For the three nine September 30, 2019, $314,000 $1.1 three nine September 30, 2018 $481,000 $1.4 three nine September 30, 2019 $225,000 $444,000, $358,000 September 30, 2019. The following table presents the future operating lease payments and lease liability included on the condensed balance sheet related to the Company’s operating lease as of September 30, 2019 ( Year Ending December 31, 2019 (remaining three months of the year) $ 418 2020 1,085 2021 1,123 2022 1,162 2023 1,203 Thereafter 1,138 6,128 Less: Imputed interest (937 ) Leasehold liability as of September 30, 2019 $ 5,192 Indemnification In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and may may not not The Company indemnifies each of its directors and officers for certain events or occurrences, subject to certain limits, while the director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws. The term of the indemnification period lasts as long as a director may may not Legal Proceedings Except as set forth below, we are not may Between May 22, 2017 May 25, 2017, three January 2015 No. 17 02240, No. 17 02284, No. 17 02307. 1933. June 12, 2017, On June 22, 2017, June 23, 2017, July 21, 2017, August 9, 2017, No. 17 02284, September 22, 2017, October 31, 2017, June 20, 2018, On October 11, 2017, November 21, 2017, January 26, 2018. March 19, 2018, January 30, 2015, April 10, 2017. The Company and its directors believe that the foregoing lawsuits were without merit; however, in the interest of avoiding the cost and disruption of continuing to defend against these lawsuits, the Company entered into a settlement of the actions. The settlement is for a total of $5 $1.76 March 2018. October 24, 2018,	8. Lease Commitments The Company’s operating lease obligations primarily consist of leased office, laboratory, and manufacturing space under a non-cancelable operating lease that expires in November 2019. three $369,000 $1,015,000 $1,833,000 December 31, 2018 2017, On October 19, 2017, one December 1, 2017 November 15, 2019 15 $79,950 $82,410 December 1, 2018. The future aggregate minimum lease payments, net of sublease income, as of December 31, 2018, $899,000, December 31, 2019. Indemnification In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and may may not not The Company indemnifies each of its directors and officers for certain events or occurrences, subject to certain limits, while the director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws. The term of the indemnification period lasts as long as a director may may not Legal Proceedings Except as set forth below, we are not may Between May 22, 2017 May 25, 2017, three January 2015 No. 17 02240, No. 17 02284, No. 17 02307. 1933. June 12, 2017, On June 22, 2017, June 23, 2017, July 21, 2017, August 9, 2017, No. 17 02284, September 22, 2017, October 31, 2017, June 20, 2018, On October 11, 2017, November 21, 2017, January 26, 2018. March 19, 2018, January 30, 2015, April 10, 2017. The Company and its directors believe that the foregoing lawsuits were without merit; however, in the interest of avoiding the cost and disruption of continuing to defend against these lawsuits, the Company entered into a settlement of the actions. The settlement is for a total of $5 $1.76 March 2018. October 24, 2018,

Note 7 - Stockholders' Equity (

Note 7 - Stockholders' Equity (Deficit)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Stockholders' Equity Note Disclosure [Text Block]	7. Convertible Preferred Stock The Company’s certificate of incorporation, as amended and restated, authorizes the Company to issue up to 5,000,000 $0.001 44,923 September 30, 2019. Series A Convertible Preferred Stock On February 14, 2018, $38.0 $3.8 $41.8 2,090,000 8%, no January 2019, 2,945 December 31, 2018. September 30, 2019, 44,745 $895,000 $836,000 three September 30, 2019 2018, $2.7 $2.1 nine September 30, 2019 2018, Series B Convertible Preferred Stock On February 16, 2018, 17,979 $15.5 $0.001 no no not December 31, 2018, 1,701 nine September 30, 2019, 1,523 380,750 178 The Company evaluated the Series B convertible preferred stock issuance in accordance with the provisions of ASC 815, Derivatives and Hedging, may $5.2 February 16, 2018. Series C Convertible Preferred Stock On November 1, 2018, 728,500 8,586 $10.2 $0.001 no December 31, 2018, 2,170 nine September 30, 2019, 2,170 542,500 no Common Stock As of September 30, 2019, 100,000,000 $0.001 10,342,179 Common Stock Warrants In connection with the issuance of the Company’s Series E convertible preferred stock in September 2014 January 2015, 50% June 30, 2019, 5,380 $5,040.00 September 2, 2019. On February 16, 2018, two 1,797,900 one one $4.00 seventh 50 one seventh 60th 50 60 seven April 2019, 60 60 2 seventh September 30, 2019, 1,768,850 On July 13, 2018, 216,618 108,309 $15.80 one one third September 30, 2019 On November 1, 2018, 728,500 8,586 2,875,000 one one $4.00 5 th one 250 December 31, 2018 28,750,000 ten nine September 30, 2019, 1,998,079 $8.0 September 30, 2019, 876,840 The Company accounted for the common stock warrants issued during the year ended December 31, 2018 July 2018 November 2018 not February 2018 Expected term (years) 7 Expected volatility 55 % Risk-free interest rate 2 % Dividend rate — As of September 30, 2019 December 31, 2018, 2,753,999 4,757,539 Stock Plans In January 2015, 2015 “2015 2015 2009 “2009 2015 3,300 2015 2015 not 2009 2009 2015 first 2016, 4,225 5.0% 2018, 300,000 2015 June 8, 2018. June 19, 2019, 800,000 2015 September 30, 2019, 68,954 2015 Pursuant to the Plans, ISOs and NSOs may not 100% 10% not 110% four ten Stock option activity under the Plans is set forth below: Number of Weighted Average Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value Balance at December 31, 2018 7,954 $ 1,707.30 7.69 $ — Options expired (433 ) $ 3,015.01 Options forfeited (105 ) $ 1,929.52 Balance at September 30, 2019 7,416 $ 1,316.32 7.05 $ — Exercisable at September 30, 2019 7,181 $ 1,300.40 7.05 $ — Vested and expected to vest at September 30, 2019 7,416 $ 1,316.32 7.05 $ — There were no nine September 30, 2019. September 30, 2019, $142,000 1.0 not three nine September 30, 2019 2018. The Company’s RSUs generally vest annually over three four Number of Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term Awards outstanding at December 31, 2018 294,066 $ 17.34 3.1 Awarded 764,151 $ 1.24 Released (96,444 ) $ 17.86 Forfeited (20,205 ) $ 20.46 Awards outstanding at September 30, 2019 941,568 $ 4.15 2.0 As of September 30, 2019, $3.6 2.0 941,568 $782,000. $0.83 September 30, 2019, nine September 30, 2019 2018, $110,000 $1,000, nine September 30, 2018, $15.80. 2018 On August 22, 2018, may may not 20,000 August 28, 2019, 40,000 nine September 30, 2019 18,543 September 30, 2019, 37,056	10. Convertible Preferred Stock As of December 31, 2018, 5,000,000 $0.001 45,671 Series A Convertible Preferred Stock On February 14, 2018, $38,000,000 $3,800,000 $42.8 2,090,000 8%, no February 14, 2019. December 31, 2018, 41,800 December 31, 2018 $2.9 Series B Convertible Preferred Stock On February 16, 2018, 17,979 $15.5 $0.001 no no not December 31, 2018, 16,278 813,900 1,701 The Company evaluated the Series B convertible preferred stock issuance in accordance with the provisions of ASC 815, may $5.2 February 16, 2018. one December 31, 2018. Series C Convertible Preferred Stock On November 1, 2018, 7,285,000 8,586 $10.2 $0.001 December 31, 2018, 6,416 1,604,000 2,170 no Common Stock At December 31, 2018, 100,000,000 $0.001 3,492,200 Common Stock Warrants In connection with the issuance of the Company’s Series E convertible preferred stock in September 2014 January 2015, 50% December 31, 2018 5,380 $5,040.00 September 2, 2019 On February 16, 2018, two 1,797,900 one $4.00 seventh 50 one seventh 60th 500 60 seven 480 480. 815. not 1 2 not 815. December 31, 2018, 290,500 December 31, 2018, 1,768,850 On July 13, 2018, 216,618 108,309 $15.80 one one third 480 480. 815. not 1 2 815. December 31, 2018 108,309 On November 1, 2018, 728,500 8,586 2,875,000 one one $4.00 5 th one 250 480 480. 815. not 1 2 815. December 31, 2018 28,750,000 The Company accounted for the common stock warrants issued during the year ended December 31, 2018 November 2018 not February 2018 Expected term (years) 7 Expected volatility 55 % Risk-free interest rate 2.0 % Dividend rate — As of December 31, 2018 December 31, 2017, 4,757,539 5,380 Stock Plans In January 2015, 2015 “2015 2015 2009 “2009 2015 3,300 2015 2015 not 2009 2009 2015 first 2016, 4,225 5.0% 2018, 2015 4,167 2018, 300,000 2015 June 8, 2018. December 31, 2018, 12,668 2015 Pursuant to the Plans, ISOs and NSOs may not 100% 10% not 110% four ten Stock option activity under the Plans is set forth below: Number of Shares (in thousands) Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value (in thousands) Balance at December 31, 2017 7,664 $ 2,917.30 $ — Options granted 3,100 $ 16.70 Options exercised — $ — Options expired (2,551 ) $ 2,725.80 Options forfeited (259 ) $ 3,493.70 Balance at December 31, 2018 (7,954 ) $ 1,707.30 7.69 $ — Exercisable at December 31, 2018 (4,330 ) $ 2,469.70 6.41 — Vested and expected to vest at December 31, 2018 (7,954 ) $ 1,707.30 7.69 $ — Additional information related to the status of options as of December 31, 2018 Options Outstanding Options Vested Weighted Average Weighted Weighted Options Remaining Average Number Average Exercise Outstanding Contractual Exercise Exercisable Exercise Price (in thousands) Life Price (in thousands) Price $ 16.70 3,100 9.44 $ 16.70 — $ 16.70 $ 204.00 5 8.56 $ 204.00 2 $ 204.00 $ 820.00 798 8.21 $ 820.00 679 $ 820.00 $ 1,052.00 47 8.18 $ 1,052.00 25 $ 1,052.00 $ 1,420.00 69 7.84 $ 1,420.00 69 $ 1,420.00 $ 1,472.00 11 7.80 $ 1,472.00 6 $ 1,472.00 $ 1,620.00 7 0.44 $ 1,620.00 7 $ 1,620.00 $ 1,800.00 2,704 5.99 $ 1,800.00 2,704 $ 1,800.00 $ 1,980.00 25 1.33 $ 1,980.00 25 $ 1,980.00 $ 4,364.00 10 6.18 $ 4,364.00 9 $ 4,364.00 $ 4,404.00 23 7.44 $ 4,404.00 23 $ 4,404.00 $ 4,952.00 18 7.33 $ 4,952.00 12 $ 4,952.00 $ 5,040.00 104 2.57 $ 5,040.00 104 $ 5,040.00 $ 5,184.00 150 7.19 $ 5,184.00 103 $ 5,184.00 $ 5,196.00 301 7.17 $ 5,196.00 236 $ 5,196.00 $ 5,940.00 11 2.74 $ 5,940.00 11 $ 5,940.00 $ 6,084.00 11 6.58 $ 6,084.00 9 $ 6,084.00 $ 7,844.00 118 6.89 $ 7,844.00 92 $ 7,844.00 $ 8,100.00 379 7.22 $ 8,100.00 186 $ 8,100.00 $ 8,820.00 63 8.20 $ 8,820.00 28 $ 8,820.00 7,954 7.69 $ 1,707.57 4,330 $ 2,470.67 There were no December 31, 2018. December 31, 2018, $430,000 1.3 not December 31, 2018 2017. The Company’s RSUs generally vest annually over three four Weighted Average Weighted Average Grant Date Remaining Number of Fair Contractual Shares Value Term Awards outstanding at December 31, 2017 509 $ 2,377.80 2.87 Awarded 297,753 $ 15.00 Released (128 ) $ 2,739.70 Forfeited (4,068 ) $ 59.70 Awards outstanding at December 31, 2018 294,066 $ 17.34 3.09 As of December 31, 2018, $4.3 2.5 294,066 $0.9 $3.00 December 31, 2018, December 31, 2018 2017, $1,500 $97,000, December 31, 2017, $1,144.10. 2018 On August 22, 2018, may may not 20,000 December 31, 2018 4,401

Note 8 - Stock-based Compensati

Note 8 - Stock-based Compensation	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Share-based Payment Arrangement [Text Block]	8. Total noncash stock-based compensation expense relating to the Company’s stock options and RSUs recognized during the three nine September 30, 2019 2018, Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Cost of revenues $ 40 $ 20 $ 128 $ 56 Research and development expenses 122 137 339 353 Selling, general and administrative expenses 361 611 1,065 1,619 $ 523 $ 768 $ 1,532 $ 2,028	11. Stock-based compensation for the Company includes amortization related to all stock options, RSUs and shares issued under the ODPP and the Company’s ESPP, based on the grant-date estimated fair value. The Company estimates the fair value of stock options and shares issued under the ESPP on the date of grant using the Black-Scholes option-pricing model. The Black-Scholes model determines the fair value of stock-based payment awards based on the fair market value of the Company’s common stock on the date of grant and is affected by assumptions regarding a number of complex and subjective variables. These variables include, but are not January 2015, not not As noncash stock-based compensation expense recognized in the financial statements is based on awards ultimately expected to vest, it has been reduced for estimated forfeitures. Effective January 1, 2017, 2016 09 January 1, 2017, Total noncash stock-based compensation expense relating to the Company’s stock options, ODPP, ESPP and RSUs recognized, before taxes, during the years ended December 31, 2018 2017, Year Ended December 31, 2018 2017 Cost of revenues $ 97 $ 269 Research and development expenses 547 1,766 Selling, general and administrative expenses 2,436 2,931 $ 3,080 $ 4,966

Note 1 - Organization_2

Note 1 - Organization	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Nature of Operations [Text Block]	1. Organization, Nature of Business Avinger, Inc. (the “Company”), a Delaware corporation, was incorporated in March 2007. “OCT”) March 2016, 510 May 2018, 510 April 2019, August 2019. Liquidity Matters The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) No. 2014 15, Presentation of Financial Statements - Going Concern (Subtopic 205 40 one In the course of its activities, the Company has incurred losses and negative cash flows from operations since its inception. As of September 30, 2019, $343.2 $14.5 September 30, 2019 second 2020. $3.8 August 2019 $10.2 November 2018 $3.0 July 2018 $15.5 February 2018 nine September 30, 2019 $8.0 twelve may no not twelve no may one not Additionally, due to the substantial doubt about the Company’s ability to continue operating as a going concern and the material adverse change clause in the Loan Agreement with CRG, the entire amount of borrowings at September 30, 2019 December 31, 2018 not Public Offerings On February 16, 2018, 17,979 1,797,900 $15.5 $0.001 no no not one 1 seventh 50 one 2 seventh 60th 50 60 seven April 2019, 60 60 2 seventh 41,800 $38.0 $41.8 2,090,000 On July 12, 2018, 216,618 $16.425 one two 108,309 July 16, 2018, $3.0 $15.80 July 16, 2021. On November 1, 2018, 728,500 8,586 $10.2 $0.001 no On August 26, 2019, 3,813,559 $1.18 $3.8 February 2018 $1.18	1. Organization, Nature of Business Avinger, Inc. (the “Company”), a Delaware corporation, was incorporated in March 2007. “OCT”) March 2016, 510 May 2018, 510 510 August 2018 October 2018. Liquidity Matters The accompanying financial statements have been prepared assuming that the Company will continue as a going concern, which contemplates the realization of assets and the satisfaction of liabilities in the normal course of business. The Financial Accounting Standards Board (“FASB”) Accounting Standards Update (“ASU”) No. 2014 15, 205 40 one December 31, 2018, $328.9 $16.4 December 31, 2018 fourth 2019. $10.2 November 2018 $15.5 February 2018 $3.0 July 2018 twelve may no not twelve no may one not December 31, 2018 2017 not Public Offerings On February 3, 2016, $150,000,000 may, $50,000,000. September 2015. March 8, 2016. December 31, 2017, 18,968 $176.80 $3,187,000, $101,000 December 31, 2016, 2,737 $1,947.40 $5,171,000, $160,000 $75 one third twelve On February 16, 2018, 17,979 17,979,000 $15.5 one seventh 500 1 one seventh 60th 500 60 seven 2 41,800 $38.0 $41.8 2,090,000 On July 12, 2018, 216,618 $16.425 one two 108,309 July 16, 2018, $3.0 February 2018 $15.80 $15.80 may January 17, 2019 July 16, 2021. On November 1, 2018, 728,500 8,586 $10.2 $0.001 no

Note 2 - Summary of Significa_2

Note 2 - Summary of Significant Accounting Policies	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Basis of Presentation and Significant Accounting Policies [Text Block]	2. Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and pursuant to the rules and regulations of the SEC. The accompanying unaudited condensed interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the Company’s financial information. The results for the three nine September 30, 2019 not December 31, 2019, December 31, 2018 10 December 31, 2018, March 6, 2019. 2 10 December 31, 2018. On January 30, 2018, 1 40 June 19, 2019 , 1 - 10 June 21, 2019. not Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its common stock valuation and related stock-based compensation, the valuation of the common stock warrants, the valuation of compound embedded derivatives, provisions for doubtful accounts receivable and excess and obsolete inventories, clinical trial accruals, and its reserves for sales returns and warranty costs. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not may may Fair Value of Financial Instruments The Company has evaluated the estimated fair value of its financial instruments as of September 30, 2019 December 31, 2018. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three 1 September 30, 2019 December 31, 2018, no September 30, 2019 December 31, 2018. Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable to the extent of the amounts recorded on the balance sheets. The Company’s policy is to invest in cash and cash equivalents, consisting of money market funds. These financial instruments are held in Company accounts at one The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at September 30, 2019 December 31, 2018. The Company’s accounts receivable are due from a variety of healthcare organizations in the United States and select international markets. At September 30, 2019 December 31, 2018, no 10% three nine September 30, 2019 2018, no 10% The Company manufactures its commercial products in-house, including Pantheris and the Ocelot family of catheters. Certain of the Company’s product components and sub-assemblies continue to be manufactured by sole suppliers. Disruption in component or sub-assembly supply from these manufacturers or from in-house production would have a negative impact on the Company’s financial position and results of operations. The Company is subject to certain risks, including that its devices may not no not third Existing or future devices developed by the Company may may may Revenue Recognition The Company’s revenues are derived from ( 1 2 3 1. Lightbox sales: The Company sells its products directly to hospitals and medical centers. Provided all other criteria for revenue recognition have been met, the Company recognizes revenue for Lightbox sales directly to end customers when delivery and acceptance occurs, which is defined as receipt by the Company of an executed form by the customer acknowledging that the training and installation process is complete. 2. Sales of disposables: Disposable revenues consist of sales of the Company’s catheters and accessories and are recognized when the product has shipped, risk of loss and title has passed to the customer and collectability is reasonably assured. 3. Service revenue: Service contract revenue is recognized ratably over the term of the service period and maintenance contract revenue is recognized as work is performed. To date, service revenue has been insignificant. The Company offers its customers the ability to purchase or lease its Lightbox. In addition, the Company provides a Lightbox under a limited commercial evaluation program to allow certain strategic accounts to install and utilize the Lightbox for a limited trial period of three six The Company evaluates its lease and commercial evaluation program agreements and accounts for these contracts under the guidance in Accounting Standards Codification (“ASC”) 840, Leases No. 2014 09, Revenue from Contracts with Customers (Topic 606 third The Company assessed whether the embedded lease is an operating lease or sales-type lease. Based on the Company’s assessment of the guidance and given that any payments under the lease agreements are dependent upon contingent future sales, it was determined that collectability of the minimum lease payments is not not For sales through distributors, the Company recognizes revenue when title to the product and the risk of loss transfers from the Company to the distributor. The distributors are responsible for all marketing, sales, training and warranty in their respective territories. The standard terms and conditions contained in the Company’s distribution agreements do not not The Company estimates reductions in revenue for potential returns of products by customers. In making such estimates, management analyzes historical returns, current economic trends and changes in customer demand and acceptance of its products. The Company expenses shipping and handling costs as incurred and includes them in the cost of revenues. When the Company bills shipping and handling costs to customers, such amounts billed are included as a component of revenue. Cost of Revenues Cost of revenues consists primarily of manufacturing overhead costs, material costs and direct labor. A significant portion of the Company’s cost of revenues currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of revenues also includes depreciation expense for the Lightboxes under lease agreements and certain direct costs such as shipping costs. Product Warranty Costs The Company typically offers a one Balance at December 31, 2018 $ 272 Warranty provision 70 Usage/release (128 ) Balance at September 30, 2019 $ 214 Net Loss per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Any common stock shares subject to repurchase are excluded from the calculations as the continued vesting of such shares is contingent upon the holders’ continued service to the Company. As of September 30, 2019 December 31, 2018, no Net loss per share attributable to common stockholders was determined as follows (in thousands, except per share data): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net loss attributable to common stockholders $ (5,518 ) $ (6,224 ) $ (17,014 ) $ (28,766 ) Weighted average common stock outstanding 7,900 1,119 6,189 669 Net loss per share attributable to common stockholders, basic and diluted $ (0.70 ) $ (5.56 ) $ (2.75 ) $ (43.00 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an anti-dilutive impact due to losses reported: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Common stock warrant equivalents 2,757,741 1,867,226 3,346,568 1,511,832 Common stock options 7,444 8,472 7,596 7,246 Convertible preferred stock 44,923 4,450 45,046 3,969 Unvested restricted stock units 371,651 84,848 316,575 374 3,181,759 1,964,996 3,715,785 1,523,421 Segment and Geographical Information The Company operates and manages its business as one three September 30, 2019 2018, 96% 94%, nine September 30, 2019 2018, 94% 94%, Recent Accounting Pronouncements Adopted: In May 2014, No. 2014 09 , Revenue from Contracts with Customers (Topic 606 605, Revenue Recognition August 2015, No. 2015 14, Revenue from Contracts with Customers (Topic 606 one December 15, 2017. In March 2016, No. 2016 08, Revenue from Contracts with Customers (Topic 606 ) In April 2016, No. 2016 10, Revenue from Contracts with Customers (Topic 606 ) Identifying Performance Obligations and Licensing In May 2016, No. 2016 12, Revenue from Contracts with Customers (Topic 606 ) Narrow-Scope Improvements and Practical Expedients The Company adopted ASC 606 January 1, 2018, not In May 2017, No. 2017 09, Compensation—Stock Compensation (Topic 718 ) 718. January 1, 2018 not In August 2016, No. 2016 15, Statement of Cash Flows (Topic 230 ): Classification of Certain Cash Receipts and Cash Payments December 15, 2017, January 1, 2018 not In February 2016, No. 2016 02, Leases (Topic 842 ). 842 one July, 842 No. 2018 10, Codification Improvements to Topic 842, Leases No. 2018 11, Leases (Topic 842 ): Targeted Improvements first 2019 January 1, 2019. $1.8 no $240,000 $720,000 three nine September 30, 2018 In June 2018, No. 2018 07, Compensation-Stock Compensation (Topic 718 ): Improvements to Nonemployee Share-Based Payment Accounting, 718 718 not 1 2 606. December 15, 2018, no 606. July 1, 2018 not	2. Basis of Presentation The accompanying financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and pursuant to the rules and regulations of the SEC (“SEC”). On January 30, 2018, 1 40 not January 30, 2018. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its common stock valuation and related stock-based compensation, the valuation of the common stock warrants, the valuation of compound embedded derivatives, provisions for doubtful accounts receivable and excess and obsolete inventories, clinical trial accruals, and its reserves for sales returns and warranty costs. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not may may Fair Value of Financial Instruments The Company has evaluated the estimated fair value of its financial instruments as of December 31, 2018 2017. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three December 31, 2018 2017, no December 31, 2018 2017. Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable to the extent of the amounts recorded on the balance sheets. The Company’s policy is to invest in cash and cash equivalents, consisting of money market funds. These financial instruments are held in Company accounts at one The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at December 31, 2018 2017. The Company’s accounts receivable are due from a variety of healthcare organizations in the United States and select international markets. At December 31, 2018 2017, no 10% December 31, 2018 2017, no 10% The Company manufactures its commercial products in-house, including Pantheris and the Ocelot family of catheters. Certain of the Company’s product components and sub-assemblies continue to be manufactured by sole suppliers. Disruption in component or sub-assembly supply from these manufacturers or from in-house production would have a negative impact on the Company’s financial position and results of operations. The Company is subject to certain risks, including that its devices may not no not third Existing or future devices developed by the Company may may may Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not not Inventories Inventories are valued at the lower of cost or net realizable value. Cost is determined using the first first may Property and Equipment Property and equipment are recorded at cost. Repairs and maintenance costs are expensed as incurred. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets of three five Deferred Offering Costs Deferred offering costs, which primarily consist of direct incremental legal and accounting fees relating to the Company’s offerings of equity securities to Lincoln Park, were capitalized. The deferred offering costs were be offset against proceeds from the public offering upon the effectiveness of the public offerings in fiscal 2018. December 31, 2018 2017, zero $464,000 2018 Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not not December 31, 2018. Revenue Recognition The Company’s revenues are derived from ( 1 2 3 605 10, The Company’s revenue recognition policies generally result in revenue recognition at the following points: 1. Lightbox sales: The Company sells its products directly to hospitals and medical centers. Provided all other criteria for revenue recognition have been met, the Company recognizes revenue for Lightbox sales directly to end customers when delivery and acceptance occurs, which is defined as receipt by the Company of an executed form by the customer acknowledging that the training and installation process is complete. 2. Sales of disposables: Disposable revenues consist of sales of the Company’s catheters and accessories and are recognized when the product has shipped, risk of loss and title has passed to the customer and collectability is reasonably assured. 3. Service revenue: Service revenue is recognized ratably over the term of the service period. To date service revenue has been insignificant. The Company offers its customers the ability to purchase or lease its Lightbox. In addition, the Company provides a Lightbox under a limited commercial evaluation program to allow certain strategic accounts to install and utilize the Lightbox for a limited trial period of three six The Company assessed whether the embedded lease is an operating lease or sales-type lease. Based on the Company’s assessment of the guidance and given that any payments under the lease agreements are dependent upon contingent future sales, it was determined that collectability of the minimum lease payments is not not For sales through distributors, the Company recognizes revenue when title to the product and the risk of loss transfers from the Company to the distributor. The distributors are responsible for all marketing, sales, training and warranty in their respective territories. The standard terms and conditions contained in the Company’s distribution agreements do not not The Company estimates reductions in revenue for potential returns of products by customers. In making such estimates, management analyzes historical returns, current economic trends and changes in customer demand and acceptance of its products. The Company expenses shipping and handling costs as incurred and includes them in the cost of revenues. In those cases where the Company bills shipping and handling costs to customers, it will classify the amounts billed as a component of revenue. Cost of Revenues Cost of revenues consists primarily of manufacturing overhead costs, material costs and direct labor. A significant portion of the Company’s cost of revenues currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of revenues also includes depreciation expense for the Lightboxes under lease agreements, product warranty costs, product written-off due to obsolescence, and certain direct costs such as shipping costs. Product Warranty Costs The Company typically offers a one Year Ended December 31, 2018 2017 Balance, beginning of year $ 390 $ 509 Warranty provision 333 306 Usage/Release (451 ) (425 ) Balance, end of year $ 272 $ 390 Research and Development The Company expenses research and development costs as incurred. Research and development expenses include personnel and personnel-related costs, costs associated with pre-clinical and clinical development activities, and costs for prototype products that are manufactured prior to market approval for that prototype product; internal and external costs associated with the Company’s regulatory compliance and quality assurance functions, including the costs of outside consultants and contractors that assist in the process of submitting and maintaining regulatory filings, and overhead costs, including allocated facility and related expenses. Clinical Trials The Company accrues and expenses costs for its clinical trial activities performed by third Common Stock Valuation and Stock-Based Compensation Stock-based compensation for the Company includes amortization related to all stock options, restricted stock units (“RSUs”) and shares issued under the employee stock purchase plan (“ESPP”), based on the grant-date estimated fair value. The fair value of stock options is estimated on the date of grant using the Black-Scholes option pricing model and recognized as expense on a straight-line basis over the vesting period of the award. The Company measures the fair value of RSUs using the closing stock price of a share of the Company’s common stock on the grant date and is recognized as expense on a straight-line basis over the vesting period of the award. Because noncash stock-based compensation expense is based on awards ultimately expected to vest, it is reduced by an estimate for future forfeitures. The Company estimates a forfeiture rate for its stock options and RSUs based on an analysis of its actual forfeiture experience and other factors. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates. Prior to the Company’s IPO in January 2015, third Foreign Currency The Company records net gains and losses resulting from foreign exchange transactions as a component of foreign currency exchange losses in other income (expense), net. During the years ended December 31, 2018 2017, $13,000 $11,000 Income Taxes The Company utilizes the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to record interest and penalties on uncertain tax positions as income tax expense when they occur. During the years ended December 31, 2018 2017, not Net Loss per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholder by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Any common stock shares subject to repurchase are excluded from the calculations as the continued vesting of such shares is contingent upon the holders’ continued service to the Company. As of December 31, 2018 2017, no Net loss per share attributable to common stockholders was determined as follows (in thousands, except per share data): Year Ended December 31, 2018 2017 Net loss attributable to common stockholders $ (35,692 ) $ (48,732 ) Weighted average common stock outstanding 1,068 65 Net loss per share attributable to common stockholders, basic and diluted $ (33.42 ) $ 749.72 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an antidilutive impact due to losses reported: Year Ended December 31, 2018 2017 Common stock options 7,179 7,664 Convertible preferred stock 41,398 - Unvested restricted stock units 92,245 508 Common stock warrants 2,077,871 5,371 2,218,693 13,543 Comprehensive Loss For the years ended December 31, 2018 2017, no Segment and Geographical Information The Company operates and manages its business as one December 31, 2018 2017, 94% 95%, Recent Accounting Pronouncements Adopted: In May 2014, No. 2014 09, “ 606 ” 605, August 2015, No. 2015 14, 606 one December 15, 2017. In March 2016, No. 2016 08, 606 In April 2016, No. 2016 10, 606 In May 2016, No. 2016 12, 606 The Company adopted ASC 606 January 1, 2018, not In May 2017, No. 2017 09, 718 718. January 1, 2018 not In August 2016, No. 2016 15, 230 December 15, 2017, January 1, 2018 not In November 2016, No. 2016 18, 230 2016 18 2016 18 December 15, 2017. January 1, 2018 not Pending Adoption: In February 2016, No. 2016 02 842 842 one July, 842 No. 2018 10, 842 , No. 2018 11, 842 first 2019 The Company has evaluated the impact of the adoption of these standards on January 1, 2019, $1.8 no In June 2018, No. 2018 07, 718 718 718 not 1 2 606. December 15, 2018, no 606. January 1, 2019 not

Note 3 - Fair Value Measureme_2

Note 3 - Fair Value Measurements	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Fair Value Disclosures [Text Block]	3. The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three Level 1—Quoted Level 2—Inputs 1 not Level 3—Unobservable no As of September 30, 2019 December 31, 2018, 1 September 30, 2019 December 31, 2018, no 2 3. no three nine September 30, 2019 2018.	3. The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three Level 1—Quoted Level 2—Inputs 1 not Level 3—Unobservable no As of December 31, 2018 2017, 1 December 31, 2018 2017, no 2. December 31, 2018, 3.. December 31, 2017, no 3. no December 31, 2018 2017.

Note 4 - Inventories

Note 4 - Inventories	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Inventory Disclosure [Text Block]	4. Inventories consisted of the following (in thousands): September 30, December 31, 2019 2018 Raw materials $ 1,898 $ 2,102 Work-in-process 544 158 Finished products 1,670 1,162 Total inventories $ 4,112 $ 3,422	4. Inventories consisted of the following (in thousands): December 31, 2018 2017 Raw materials $ 1,162 $ 1,286 Work-in-process 158 - Finished products 2,102 3,009 Total inventories $ 3,422 $ 4,295

Note 5 - Property and Equipment

Note 5 - Property and Equipment, Net	12 Months Ended
	Dec. 31, 2018
Notes to Financial Statements
Property, Plant and Equipment Disclosure [Text Block]	5. Property and equipment, net, consisted of the following (in thousands): December 31, 2018 2017 Computer software $ 124 $ 248 Computer equipment 197 717 Machinery and equipment 1,784 3,351 Furniture and fixture 78 517 Leasehold improvements 326 638 Equipment held by customers 2,718 2,997 5,227 8,468 Less: Accumulated depreciation and amortization (3,155 ) (5,564 ) Add: Construction-in-progress 6 46 $ 2,078 $ 2,950 Depreciation expense for the years ended December 31, 2018 2017, $934,000 $1,476,000, not $499,000 $735,000, December 31, 2018 2017, $1,399,000 $1,811,000 December 31, 2018 2017,

Note 6 - Accrued Expenses and O

Note 6 - Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2018
Notes to Financial Statements
Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]	6. Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, 2018 2017 Accrued litigation settlement $ - $ 1,760 Accrued interest payable - 364 Accrued sales tax 435 - Accrued professional fees 41 288 Accrued travel expenses 74 90 Accrued product warranty costs 272 390 Accrued clinical trial costs 111 57 Accrued restructuring charge 98 98 Other accrued liabilities 418 550 $ 1,449 $ 3,597

Note 7 - Borrowings

Note 7 - Borrowings	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Debt Disclosure [Text Block]	5. CRG On September 22, 2015, $50,000,000 March 29, 2017. $30,000,000 September 22, 2015. $10,000,000 June 15, 2016 On February 14, 2018, $38,000,000 $3,800,000 7, Under the Loan Agreement, as amended, no first 2020. first 2020 not 12.5%. third 2021, $1.2 $2.4 2021, $4.8 2022 $2.4 2023. The Company may 5.0% 1.0% no fifth 1.5% 7.0% The Loan Agreement requires that the Company adheres to certain affirmative and negative covenants, including financial reporting requirements, certain minimum financial covenants for pre-specified liquidity and revenue requirements and a prohibition against the incurrence of indebtedness, or creation of additional liens, other than as specifically permitted by the terms of the Loan Agreement. In particular, the covenants of the original Loan Agreement included a covenant that the Company maintain a minimum of $5,000,000 2.0 may On February 14, 2018, No. 2 ● extend the interest only payment period and the period during which the Company may June 30, 2021; ● provide for a 15% ● permit the Company to make the entire interest payment for payment dates in 2018 2019 no ● extend the maturity date to June 30, 2023; ● modify certain of the covenants, including the indebtedness covenant, lien covenant and restricted payments covenant, to eliminate or modify permitted exceptions to the restrictions in those covenants; ● modify the financial covenants to reduce the minimum liquidity requirement to $3,500,000 2018 2019, $15,000,000 2020, $20,000,000 2021 $25,000,000 2022; ● provide CRG with board observer rights. As of September 30, 2019, As of September 30, 2019, Year Ending December 31, 2019 (remaining three months of the year) $ — 2020 799 2021 3,403 2022 5,522 2023 3,981 13,705 Less: Amount of PIK additions and final facility fee to be accreted subsequent to September 30, 2019 (4,497 ) Less: Amount representing debt financing costs (630 ) Borrowings, as of September 30, 2019 $ 8,578 In connection with drawdowns under the Loan Agreement, the Company recorded aggregate debt discounts of $1.3 September 30, 2019 December 31, 2018, $630,000 $757,000, $42,000 $30,000 three September 30, 2019 2018, $127,000 $84,000 nine September 30, 2019 2018, three September 30, 2019 2018, $377,000 $362,000, nine $1.1 $5.4 Due to the substantial doubt about the Company’s ability to continue operating as a going concern and the material adverse change clause in the Loan Agreement with CRG, the entire amount of borrowings at September 30, 2019 December 31, 2018 not	7. CRG On September 22, 2015, $50,000,000 March 29, 2017. $30,000,000 September 22, 2015. $10,000,000 June 15, 2016 $10,000,000, March 29, 2017, not On October 28, 2016, 2016 $18,000,000. February 14, 2018, $38,000,000 $3,800,000 7, December 31, 2018, $3,800,000 Under the Loan Agreement, as in effect prior to amendment, the first sixteen eight 12.5% September 30, 2015. 12.5% 8.5% 4.0% eight two September 30, 2021. The Company may 5.0% 1.0% no fifth 1.5% 7.0% $5,000,000 $7,000,000 2015, $23,000,000 2016, $40,000,000 2017, $50,000,000 2018, $60,000,000 2019 $70,000,000 2020 2.0 may On January 24, 2018, $5,000,0000 $2,500,000 January 1, 2018 February 28, 2018, $5,000,000 On February 14, 2018, No. 2 ● extend the interest only payment period and the period during which the Company may June 30, 2021; ● provide for a 15% ● permit the Company to make the entire interest payment for payment dates in 2018 2019 no ● extend the maturity date to June 30, 2023; ● modify certain of the covenants, including the indebtedness covenant, lien covenant and restricted payments covenant, to eliminate or modify permitted exceptions to the restrictions in those covenants; ● modify the financial covenants to reduce the minimum liquidity requirement to $3,500,000 2018 2019, $15,000,000 2020, $20,000,000 2021 $25,000,000 2022; ● provide CRG with board observer rights. As of December 31, 2018, As of December 31, 2018, Principal and PIK Period Ending December 31, Loan Repayments 2019 $ — 2020 — 2021 — 2022 — 2023 and after 2,000 2,000 Add: PIK 6,243 8,243 Less: Amount representing debt financing costs (757 ) Borrowings, as of December 31, 2018 $ 7,486 Contemporaneously with the execution of the Loan Agreement in September 2015, $5,000,000 870 September 22, 2015 $5,596.40 10 September 21, 2015. September 22, 2015 $5,588.00 $8.40 In connection with the initial drawdown under the Loan Agreement, the Company recorded a debt discount of $876,000 $450,000, $541,000 $115,000 June 2016 February 2018, $275,000 $150,000, $125,000. No.2 February 2018, $154,000 December 31, 2018 2017, $757,000 $716,000, $117,000 $203,000 December 31, 2018 2017, As noted in Note 1 December 31, 2018 2017 not

Note 8 - Commitments and Contin

Note 8 - Commitments and Contingencies	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	6. Lease Commitments The Company’s operating lease obligations primarily consist of leased office, laboratory, and manufacturing space under a non-cancelable operating lease that originally were to expire in November 2019. $369,000 On October 19, 2017, one December 1, 2017 November 15, 2019 15 $82,410 Upon the adoption of Topic 842 January 1, 2019, $1.8 On April 1, 2019, five November 30, 2019. November 30, 2024. $5.8 November 2024, December 1, 2019. not In connection with the amendment the Company adjusted its right-of-use asset and lease liability to $6.0 6.5% not For the three nine September 30, 2019, $314,000 $1.1 three nine September 30, 2018 $481,000 $1.4 three nine September 30, 2019 $225,000 $444,000, $358,000 September 30, 2019. The following table presents the future operating lease payments and lease liability included on the condensed balance sheet related to the Company’s operating lease as of September 30, 2019 ( Year Ending December 31, 2019 (remaining three months of the year) $ 418 2020 1,085 2021 1,123 2022 1,162 2023 1,203 Thereafter 1,138 6,128 Less: Imputed interest (937 ) Leasehold liability as of September 30, 2019 $ 5,192 Indemnification In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and may may not not The Company indemnifies each of its directors and officers for certain events or occurrences, subject to certain limits, while the director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws. The term of the indemnification period lasts as long as a director may may not Legal Proceedings Except as set forth below, we are not may Between May 22, 2017 May 25, 2017, three January 2015 No. 17 02240, No. 17 02284, No. 17 02307. 1933. June 12, 2017, On June 22, 2017, June 23, 2017, July 21, 2017, August 9, 2017, No. 17 02284, September 22, 2017, October 31, 2017, June 20, 2018, On October 11, 2017, November 21, 2017, January 26, 2018. March 19, 2018, January 30, 2015, April 10, 2017. The Company and its directors believe that the foregoing lawsuits were without merit; however, in the interest of avoiding the cost and disruption of continuing to defend against these lawsuits, the Company entered into a settlement of the actions. The settlement is for a total of $5 $1.76 March 2018. October 24, 2018,	8. Lease Commitments The Company’s operating lease obligations primarily consist of leased office, laboratory, and manufacturing space under a non-cancelable operating lease that expires in November 2019. three $369,000 $1,015,000 $1,833,000 December 31, 2018 2017, On October 19, 2017, one December 1, 2017 November 15, 2019 15 $79,950 $82,410 December 1, 2018. The future aggregate minimum lease payments, net of sublease income, as of December 31, 2018, $899,000, December 31, 2019. Indemnification In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and may may not not The Company indemnifies each of its directors and officers for certain events or occurrences, subject to certain limits, while the director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws. The term of the indemnification period lasts as long as a director may may not Legal Proceedings Except as set forth below, we are not may Between May 22, 2017 May 25, 2017, three January 2015 No. 17 02240, No. 17 02284, No. 17 02307. 1933. June 12, 2017, On June 22, 2017, June 23, 2017, July 21, 2017, August 9, 2017, No. 17 02284, September 22, 2017, October 31, 2017, June 20, 2018, On October 11, 2017, November 21, 2017, January 26, 2018. March 19, 2018, January 30, 2015, April 10, 2017. The Company and its directors believe that the foregoing lawsuits were without merit; however, in the interest of avoiding the cost and disruption of continuing to defend against these lawsuits, the Company entered into a settlement of the actions. The settlement is for a total of $5 $1.76 March 2018. October 24, 2018,

Note 9 - Restructuring Charges

Note 9 - Restructuring Charges and Expenses	12 Months Ended
	Dec. 31, 2018
Notes to Financial Statements
Restructuring and Related Activities Disclosure [Text Block]	9. In April 2017, 33%. $519,000, December 31, 2018, April 2017 44 In September 2017, 24 $416,000, October 2017, one $388,000 December 31, 2018, 24 December 31, 2018 2017, $98,000

Note 10 - Stockholders' Equity

Note 10 - Stockholders' Equity (Deficit)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Stockholders' Equity Note Disclosure [Text Block]	7. Convertible Preferred Stock The Company’s certificate of incorporation, as amended and restated, authorizes the Company to issue up to 5,000,000 $0.001 44,923 September 30, 2019. Series A Convertible Preferred Stock On February 14, 2018, $38.0 $3.8 $41.8 2,090,000 8%, no January 2019, 2,945 December 31, 2018. September 30, 2019, 44,745 $895,000 $836,000 three September 30, 2019 2018, $2.7 $2.1 nine September 30, 2019 2018, Series B Convertible Preferred Stock On February 16, 2018, 17,979 $15.5 $0.001 no no not December 31, 2018, 1,701 nine September 30, 2019, 1,523 380,750 178 The Company evaluated the Series B convertible preferred stock issuance in accordance with the provisions of ASC 815, Derivatives and Hedging, may $5.2 February 16, 2018. Series C Convertible Preferred Stock On November 1, 2018, 728,500 8,586 $10.2 $0.001 no December 31, 2018, 2,170 nine September 30, 2019, 2,170 542,500 no Common Stock As of September 30, 2019, 100,000,000 $0.001 10,342,179 Common Stock Warrants In connection with the issuance of the Company’s Series E convertible preferred stock in September 2014 January 2015, 50% June 30, 2019, 5,380 $5,040.00 September 2, 2019. On February 16, 2018, two 1,797,900 one one $4.00 seventh 50 one seventh 60th 50 60 seven April 2019, 60 60 2 seventh September 30, 2019, 1,768,850 On July 13, 2018, 216,618 108,309 $15.80 one one third September 30, 2019 On November 1, 2018, 728,500 8,586 2,875,000 one one $4.00 5 th one 250 December 31, 2018 28,750,000 ten nine September 30, 2019, 1,998,079 $8.0 September 30, 2019, 876,840 The Company accounted for the common stock warrants issued during the year ended December 31, 2018 July 2018 November 2018 not February 2018 Expected term (years) 7 Expected volatility 55 % Risk-free interest rate 2 % Dividend rate — As of September 30, 2019 December 31, 2018, 2,753,999 4,757,539 Stock Plans In January 2015, 2015 “2015 2015 2009 “2009 2015 3,300 2015 2015 not 2009 2009 2015 first 2016, 4,225 5.0% 2018, 300,000 2015 June 8, 2018. June 19, 2019, 800,000 2015 September 30, 2019, 68,954 2015 Pursuant to the Plans, ISOs and NSOs may not 100% 10% not 110% four ten Stock option activity under the Plans is set forth below: Number of Weighted Average Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value Balance at December 31, 2018 7,954 $ 1,707.30 7.69 $ — Options expired (433 ) $ 3,015.01 Options forfeited (105 ) $ 1,929.52 Balance at September 30, 2019 7,416 $ 1,316.32 7.05 $ — Exercisable at September 30, 2019 7,181 $ 1,300.40 7.05 $ — Vested and expected to vest at September 30, 2019 7,416 $ 1,316.32 7.05 $ — There were no nine September 30, 2019. September 30, 2019, $142,000 1.0 not three nine September 30, 2019 2018. The Company’s RSUs generally vest annually over three four Number of Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term Awards outstanding at December 31, 2018 294,066 $ 17.34 3.1 Awarded 764,151 $ 1.24 Released (96,444 ) $ 17.86 Forfeited (20,205 ) $ 20.46 Awards outstanding at September 30, 2019 941,568 $ 4.15 2.0 As of September 30, 2019, $3.6 2.0 941,568 $782,000. $0.83 September 30, 2019, nine September 30, 2019 2018, $110,000 $1,000, nine September 30, 2018, $15.80. 2018 On August 22, 2018, may may not 20,000 August 28, 2019, 40,000 nine September 30, 2019 18,543 September 30, 2019, 37,056	10. Convertible Preferred Stock As of December 31, 2018, 5,000,000 $0.001 45,671 Series A Convertible Preferred Stock On February 14, 2018, $38,000,000 $3,800,000 $42.8 2,090,000 8%, no February 14, 2019. December 31, 2018, 41,800 December 31, 2018 $2.9 Series B Convertible Preferred Stock On February 16, 2018, 17,979 $15.5 $0.001 no no not December 31, 2018, 16,278 813,900 1,701 The Company evaluated the Series B convertible preferred stock issuance in accordance with the provisions of ASC 815, may $5.2 February 16, 2018. one December 31, 2018. Series C Convertible Preferred Stock On November 1, 2018, 7,285,000 8,586 $10.2 $0.001 December 31, 2018, 6,416 1,604,000 2,170 no Common Stock At December 31, 2018, 100,000,000 $0.001 3,492,200 Common Stock Warrants In connection with the issuance of the Company’s Series E convertible preferred stock in September 2014 January 2015, 50% December 31, 2018 5,380 $5,040.00 September 2, 2019 On February 16, 2018, two 1,797,900 one $4.00 seventh 50 one seventh 60th 500 60 seven 480 480. 815. not 1 2 not 815. December 31, 2018, 290,500 December 31, 2018, 1,768,850 On July 13, 2018, 216,618 108,309 $15.80 one one third 480 480. 815. not 1 2 815. December 31, 2018 108,309 On November 1, 2018, 728,500 8,586 2,875,000 one one $4.00 5 th one 250 480 480. 815. not 1 2 815. December 31, 2018 28,750,000 The Company accounted for the common stock warrants issued during the year ended December 31, 2018 November 2018 not February 2018 Expected term (years) 7 Expected volatility 55 % Risk-free interest rate 2.0 % Dividend rate — As of December 31, 2018 December 31, 2017, 4,757,539 5,380 Stock Plans In January 2015, 2015 “2015 2015 2009 “2009 2015 3,300 2015 2015 not 2009 2009 2015 first 2016, 4,225 5.0% 2018, 2015 4,167 2018, 300,000 2015 June 8, 2018. December 31, 2018, 12,668 2015 Pursuant to the Plans, ISOs and NSOs may not 100% 10% not 110% four ten Stock option activity under the Plans is set forth below: Number of Shares (in thousands) Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value (in thousands) Balance at December 31, 2017 7,664 $ 2,917.30 $ — Options granted 3,100 $ 16.70 Options exercised — $ — Options expired (2,551 ) $ 2,725.80 Options forfeited (259 ) $ 3,493.70 Balance at December 31, 2018 (7,954 ) $ 1,707.30 7.69 $ — Exercisable at December 31, 2018 (4,330 ) $ 2,469.70 6.41 — Vested and expected to vest at December 31, 2018 (7,954 ) $ 1,707.30 7.69 $ — Additional information related to the status of options as of December 31, 2018 Options Outstanding Options Vested Weighted Average Weighted Weighted Options Remaining Average Number Average Exercise Outstanding Contractual Exercise Exercisable Exercise Price (in thousands) Life Price (in thousands) Price $ 16.70 3,100 9.44 $ 16.70 — $ 16.70 $ 204.00 5 8.56 $ 204.00 2 $ 204.00 $ 820.00 798 8.21 $ 820.00 679 $ 820.00 $ 1,052.00 47 8.18 $ 1,052.00 25 $ 1,052.00 $ 1,420.00 69 7.84 $ 1,420.00 69 $ 1,420.00 $ 1,472.00 11 7.80 $ 1,472.00 6 $ 1,472.00 $ 1,620.00 7 0.44 $ 1,620.00 7 $ 1,620.00 $ 1,800.00 2,704 5.99 $ 1,800.00 2,704 $ 1,800.00 $ 1,980.00 25 1.33 $ 1,980.00 25 $ 1,980.00 $ 4,364.00 10 6.18 $ 4,364.00 9 $ 4,364.00 $ 4,404.00 23 7.44 $ 4,404.00 23 $ 4,404.00 $ 4,952.00 18 7.33 $ 4,952.00 12 $ 4,952.00 $ 5,040.00 104 2.57 $ 5,040.00 104 $ 5,040.00 $ 5,184.00 150 7.19 $ 5,184.00 103 $ 5,184.00 $ 5,196.00 301 7.17 $ 5,196.00 236 $ 5,196.00 $ 5,940.00 11 2.74 $ 5,940.00 11 $ 5,940.00 $ 6,084.00 11 6.58 $ 6,084.00 9 $ 6,084.00 $ 7,844.00 118 6.89 $ 7,844.00 92 $ 7,844.00 $ 8,100.00 379 7.22 $ 8,100.00 186 $ 8,100.00 $ 8,820.00 63 8.20 $ 8,820.00 28 $ 8,820.00 7,954 7.69 $ 1,707.57 4,330 $ 2,470.67 There were no December 31, 2018. December 31, 2018, $430,000 1.3 not December 31, 2018 2017. The Company’s RSUs generally vest annually over three four Weighted Average Weighted Average Grant Date Remaining Number of Fair Contractual Shares Value Term Awards outstanding at December 31, 2017 509 $ 2,377.80 2.87 Awarded 297,753 $ 15.00 Released (128 ) $ 2,739.70 Forfeited (4,068 ) $ 59.70 Awards outstanding at December 31, 2018 294,066 $ 17.34 3.09 As of December 31, 2018, $4.3 2.5 294,066 $0.9 $3.00 December 31, 2018, December 31, 2018 2017, $1,500 $97,000, December 31, 2017, $1,144.10. 2018 On August 22, 2018, may may not 20,000 December 31, 2018 4,401

Note 11 - Stock-based Compensat

Note 11 - Stock-based Compensation	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes to Financial Statements
Share-based Payment Arrangement [Text Block]	8. Total noncash stock-based compensation expense relating to the Company’s stock options and RSUs recognized during the three nine September 30, 2019 2018, Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Cost of revenues $ 40 $ 20 $ 128 $ 56 Research and development expenses 122 137 339 353 Selling, general and administrative expenses 361 611 1,065 1,619 $ 523 $ 768 $ 1,532 $ 2,028	11. Stock-based compensation for the Company includes amortization related to all stock options, RSUs and shares issued under the ODPP and the Company’s ESPP, based on the grant-date estimated fair value. The Company estimates the fair value of stock options and shares issued under the ESPP on the date of grant using the Black-Scholes option-pricing model. The Black-Scholes model determines the fair value of stock-based payment awards based on the fair market value of the Company’s common stock on the date of grant and is affected by assumptions regarding a number of complex and subjective variables. These variables include, but are not January 2015, not not As noncash stock-based compensation expense recognized in the financial statements is based on awards ultimately expected to vest, it has been reduced for estimated forfeitures. Effective January 1, 2017, 2016 09 January 1, 2017, Total noncash stock-based compensation expense relating to the Company’s stock options, ODPP, ESPP and RSUs recognized, before taxes, during the years ended December 31, 2018 2017, Year Ended December 31, 2018 2017 Cost of revenues $ 97 $ 269 Research and development expenses 547 1,766 Selling, general and administrative expenses 2,436 2,931 $ 3,080 $ 4,966

Note 12 - Income Taxes

Note 12 - Income Taxes	12 Months Ended
	Dec. 31, 2018
Notes to Financial Statements
Income Tax Disclosure [Text Block]	12. For the years ended December 31, 2018 2017, zero Year Ended December 31, 2018 2017 Tax at federal statutory rate $ (5,787 ) $ (16,565 ) Federal Tax rate remeasurement — 35,953 State taxes, net of federal benefit (1,023 ) 993 Permanent differences 228 525 Change in valuation allowance 6,582 (22,554 ) Research credits — (229 ) Other — 1,877 Provision for taxes $ — $ — Significant components of the Company’s net deferred tax assets as of December 31, 2018 2017 As of December 31, 2018 2017 Deferred tax assets/(liabilities): Federal, state and foreign net operating losses $ 70,286 $ 62,057 Research and other credits 3,655 3,632 Fixed assets (176 ) 604 Accruals and other 4,317 4,208 Total net deferred tax assets 78,082 70,501 Less: Valuation allowance (78,082 ) (70,501 ) Net deferred tax assets $ — $ — The valuation allowance increased by $7.6 $20.9 December 31, 2018 2017, The Tax Cuts and Jobs Act of 2017 December 22, 2017. 35% 21% January 1, 2018. On December 22, 2017, No. 118 118 not 118, December 31, 2017. December 31, 2018, no December 31, 2017. As of December 31, 2018, $282.7 $199.3 not 2027 2018, $25.2 December 31, 2017 no As of December 31, 2018, $2.8 $3.1 2027, not may The Company's ability to utilize the net operating loss and tax credit carryforwards in the future may 382 The Company evaluates tax positions for recognition using a more-likely-than- not 50% A reconciliation of the beginning and ending amount of the gross recognized tax benefit is as follows (in thousands): As of December 31, 2018 2017 Balance at beginning of year $ 1,747 $ 1,536 Increase based on the tax positions in the current year 29 211 Decrease for tax positions of prior year (16 ) — Balance at end of year $ 1,760 $ 1,747 As of December 31, 2018, not The Company does not twelve The Company's policy is to include interest and penalties related to unrecognized tax benefits within its provision for income taxes. Due to the Company's net operating loss position, the Company has not December 31, 2018 2017.

Note 13 - Related-party Transac

Note 13 - Related-party Transactions	12 Months Ended
	Dec. 31, 2018
Notes to Financial Statements
Related Party Transactions Disclosure [Text Block]	13. In October 2015, October 2017. December 31, 2018 2017, $84,000 $188,000 December 31, 2018 2017, $12,000 $6,000

Note 14 - 401(k) Plan

Note 14 - 401(k) Plan	12 Months Ended
	Dec. 31, 2018
Notes to Financial Statements
Pension and Other Postretirement Benefits Disclosure [Text Block]	14. 401 The Company has a qualified retirement plan under section 401 may 90% may 401 may four no 401

Note 15 - Reverse Stock Split

Note 15 - Reverse Stock Split	12 Months Ended
	Dec. 31, 2018
Notes to Financial Statements
Stockholders' Equity, Reverse Stock Split [Text Block]	15. On June 19, 2019, 1 10 June 21, 2019. not December 31, 2018 2017

Significant Accounting Policies

Significant Accounting Policies (Policies)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation The accompanying unaudited condensed financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and pursuant to the rules and regulations of the SEC. The accompanying unaudited condensed interim financial statements have been prepared on the same basis as the annual financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for a fair statement of the Company’s financial information. The results for the three nine September 30, 2019 not December 31, 2019, December 31, 2018 10 December 31, 2018, March 6, 2019. 2 10 December 31, 2018. On January 30, 2018, 1 40 June 19, 2019 , 1 - 10 June 21, 2019. not	Basis of Presentation The accompanying financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”) and pursuant to the rules and regulations of the SEC (“SEC”). On January 30, 2018, 1 40 not January 30, 2018.
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its common stock valuation and related stock-based compensation, the valuation of the common stock warrants, the valuation of compound embedded derivatives, provisions for doubtful accounts receivable and excess and obsolete inventories, clinical trial accruals, and its reserves for sales returns and warranty costs. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not may may	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. Management uses significant judgment when making estimates related to its common stock valuation and related stock-based compensation, the valuation of the common stock warrants, the valuation of compound embedded derivatives, provisions for doubtful accounts receivable and excess and obsolete inventories, clinical trial accruals, and its reserves for sales returns and warranty costs. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not may may
Fair Value of Financial Instruments, Policy [Policy Text Block]	Fair Value of Financial Instruments The Company has evaluated the estimated fair value of its financial instruments as of September 30, 2019 December 31, 2018.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three 1 September 30, 2019 December 31, 2018, no September 30, 2019 December 31, 2018.	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three December 31, 2018 2017, no December 31, 2018 2017.
Concentration of Credit Risk and Other Risks and Uncertainties [Policy Text Block]	Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable to the extent of the amounts recorded on the balance sheets. The Company’s policy is to invest in cash and cash equivalents, consisting of money market funds. These financial instruments are held in Company accounts at one The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at September 30, 2019 December 31, 2018. The Company’s accounts receivable are due from a variety of healthcare organizations in the United States and select international markets. At September 30, 2019 December 31, 2018, no 10% three nine September 30, 2019 2018, no 10% The Company manufactures its commercial products in-house, including Pantheris and the Ocelot family of catheters. Certain of the Company’s product components and sub-assemblies continue to be manufactured by sole suppliers. Disruption in component or sub-assembly supply from these manufacturers or from in-house production would have a negative impact on the Company’s financial position and results of operations. The Company is subject to certain risks, including that its devices may not no not third Existing or future devices developed by the Company may may may	Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents and accounts receivable to the extent of the amounts recorded on the balance sheets. The Company’s policy is to invest in cash and cash equivalents, consisting of money market funds. These financial instruments are held in Company accounts at one The Company provides for uncollectible amounts when specific credit problems arise. Management’s estimates for uncollectible amounts have been adequate, and management believes that all significant credit risks have been identified at December 31, 2018 2017. The Company’s accounts receivable are due from a variety of healthcare organizations in the United States and select international markets. At December 31, 2018 2017, no 10% December 31, 2018 2017, no 10% The Company manufactures its commercial products in-house, including Pantheris and the Ocelot family of catheters. Certain of the Company’s product components and sub-assemblies continue to be manufactured by sole suppliers. Disruption in component or sub-assembly supply from these manufacturers or from in-house production would have a negative impact on the Company’s financial position and results of operations. The Company is subject to certain risks, including that its devices may not no not third Existing or future devices developed by the Company may may may
Revenue from Contract with Customer [Policy Text Block]	Revenue Recognition The Company’s revenues are derived from ( 1 2 3 1. Lightbox sales: The Company sells its products directly to hospitals and medical centers. Provided all other criteria for revenue recognition have been met, the Company recognizes revenue for Lightbox sales directly to end customers when delivery and acceptance occurs, which is defined as receipt by the Company of an executed form by the customer acknowledging that the training and installation process is complete. 2. Sales of disposables: Disposable revenues consist of sales of the Company’s catheters and accessories and are recognized when the product has shipped, risk of loss and title has passed to the customer and collectability is reasonably assured. 3. Service revenue: Service contract revenue is recognized ratably over the term of the service period and maintenance contract revenue is recognized as work is performed. To date, service revenue has been insignificant. The Company offers its customers the ability to purchase or lease its Lightbox. In addition, the Company provides a Lightbox under a limited commercial evaluation program to allow certain strategic accounts to install and utilize the Lightbox for a limited trial period of three six The Company evaluates its lease and commercial evaluation program agreements and accounts for these contracts under the guidance in Accounting Standards Codification (“ASC”) 840, Leases No. 2014 09, Revenue from Contracts with Customers (Topic 606 third The Company assessed whether the embedded lease is an operating lease or sales-type lease. Based on the Company’s assessment of the guidance and given that any payments under the lease agreements are dependent upon contingent future sales, it was determined that collectability of the minimum lease payments is not not For sales through distributors, the Company recognizes revenue when title to the product and the risk of loss transfers from the Company to the distributor. The distributors are responsible for all marketing, sales, training and warranty in their respective territories. The standard terms and conditions contained in the Company’s distribution agreements do not not The Company estimates reductions in revenue for potential returns of products by customers. In making such estimates, management analyzes historical returns, current economic trends and changes in customer demand and acceptance of its products. The Company expenses shipping and handling costs as incurred and includes them in the cost of revenues. When the Company bills shipping and handling costs to customers, such amounts billed are included as a component of revenue.
Cost of Goods and Service [Policy Text Block]	Cost of Revenues Cost of revenues consists primarily of manufacturing overhead costs, material costs and direct labor. A significant portion of the Company’s cost of revenues currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of revenues also includes depreciation expense for the Lightboxes under lease agreements and certain direct costs such as shipping costs.	Cost of Revenues Cost of revenues consists primarily of manufacturing overhead costs, material costs and direct labor. A significant portion of the Company’s cost of revenues currently consists of manufacturing overhead costs. These overhead costs include the cost of quality assurance, material procurement, inventory control, facilities, equipment and operations supervision and management. Cost of revenues also includes depreciation expense for the Lightboxes under lease agreements, product warranty costs, product written-off due to obsolescence, and certain direct costs such as shipping costs.
Standard Product Warranty, Policy [Policy Text Block]	Product Warranty Costs The Company typically offers a one Balance at December 31, 2018 $ 272 Warranty provision 70 Usage/release (128 ) Balance at September 30, 2019 $ 214	Product Warranty Costs The Company typically offers a one Year Ended December 31, 2018 2017 Balance, beginning of year $ 390 $ 509 Warranty provision 333 306 Usage/Release (451 ) (425 ) Balance, end of year $ 272 $ 390
Earnings Per Share, Policy [Policy Text Block]	Net Loss per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Any common stock shares subject to repurchase are excluded from the calculations as the continued vesting of such shares is contingent upon the holders’ continued service to the Company. As of September 30, 2019 December 31, 2018, no Net loss per share attributable to common stockholders was determined as follows (in thousands, except per share data): Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net loss attributable to common stockholders $ (5,518 ) $ (6,224 ) $ (17,014 ) $ (28,766 ) Weighted average common stock outstanding 7,900 1,119 6,189 669 Net loss per share attributable to common stockholders, basic and diluted $ (0.70 ) $ (5.56 ) $ (2.75 ) $ (43.00 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an anti-dilutive impact due to losses reported: Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Common stock warrant equivalents 2,757,741 1,867,226 3,346,568 1,511,832 Common stock options 7,444 8,472 7,596 7,246 Convertible preferred stock 44,923 4,450 45,046 3,969 Unvested restricted stock units 371,651 84,848 316,575 374 3,181,759 1,964,996 3,715,785 1,523,421	Net Loss per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of shares of common stock outstanding during the period, without consideration for potential dilutive common shares. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholder by the weighted average number of shares of common stock and dilutive potential shares of common stock outstanding during the period. Any common stock shares subject to repurchase are excluded from the calculations as the continued vesting of such shares is contingent upon the holders’ continued service to the Company. As of December 31, 2018 2017, no Net loss per share attributable to common stockholders was determined as follows (in thousands, except per share data): Year Ended December 31, 2018 2017 Net loss attributable to common stockholders $ (35,692 ) $ (48,732 ) Weighted average common stock outstanding 1,068 65 Net loss per share attributable to common stockholders, basic and diluted $ (33.42 ) $ 749.72 ) The following potentially dilutive securities outstanding have been excluded from the computations of diluted weighted average shares outstanding because such securities have an antidilutive impact due to losses reported: Year Ended December 31, 2018 2017 Common stock options 7,179 7,664 Convertible preferred stock 41,398 - Unvested restricted stock units 92,245 508 Common stock warrants 2,077,871 5,371 2,218,693 13,543
Segment Reporting, Policy [Policy Text Block]	Segment and Geographical Information The Company operates and manages its business as one three September 30, 2019 2018, 96% 94%, nine September 30, 2019 2018, 94% 94%,	Segment and Geographical Information The Company operates and manages its business as one December 31, 2018 2017, 94% 95%,
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements Adopted: In May 2014, No. 2014 09 , Revenue from Contracts with Customers (Topic 606 605, Revenue Recognition August 2015, No. 2015 14, Revenue from Contracts with Customers (Topic 606 one December 15, 2017. In March 2016, No. 2016 08, Revenue from Contracts with Customers (Topic 606 ) In April 2016, No. 2016 10, Revenue from Contracts with Customers (Topic 606 ) Identifying Performance Obligations and Licensing In May 2016, No. 2016 12, Revenue from Contracts with Customers (Topic 606 ) Narrow-Scope Improvements and Practical Expedients The Company adopted ASC 606 January 1, 2018, not In May 2017, No. 2017 09, Compensation—Stock Compensation (Topic 718 ) 718. January 1, 2018 not In August 2016, No. 2016 15, Statement of Cash Flows (Topic 230 ): Classification of Certain Cash Receipts and Cash Payments December 15, 2017, January 1, 2018 not In February 2016, No. 2016 02, Leases (Topic 842 ). 842 one July, 842 No. 2018 10, Codification Improvements to Topic 842, Leases No. 2018 11, Leases (Topic 842 ): Targeted Improvements first 2019 January 1, 2019. $1.8 no $240,000 $720,000 three nine September 30, 2018 In June 2018, No. 2018 07, Compensation-Stock Compensation (Topic 718 ): Improvements to Nonemployee Share-Based Payment Accounting, 718 718 not 1 2 606. December 15, 2018, no 606. July 1, 2018 not	Recent Accounting Pronouncements Adopted: In May 2014, No. 2014 09, “ 606 ” 605, August 2015, No. 2015 14, 606 one December 15, 2017. In March 2016, No. 2016 08, 606 In April 2016, No. 2016 10, 606 In May 2016, No. 2016 12, 606 The Company adopted ASC 606 January 1, 2018, not In May 2017, No. 2017 09, 718 718. January 1, 2018 not In August 2016, No. 2016 15, 230 December 15, 2017, January 1, 2018 not In November 2016, No. 2016 18, 230 2016 18 2016 18 December 15, 2017. January 1, 2018 not Pending Adoption: In February 2016, No. 2016 02 842 842 one July, 842 No. 2018 10, 842 , No. 2018 11, 842 first 2019 The Company has evaluated the impact of the adoption of these standards on January 1, 2019, $1.8 no In June 2018, No. 2018 07, 718 718 718 not 1 2 606. December 15, 2018, no 606. January 1, 2019 not
Fair Value Measurement, Policy [Policy Text Block]		Fair Value of Financial Instruments The Company has evaluated the estimated fair value of its financial instruments as of December 31, 2018 2017.
Receivable [Policy Text Block]		Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not not
Inventory, Policy [Policy Text Block]		Inventories Inventories are valued at the lower of cost or net realizable value. Cost is determined using the first first may
Property, Plant and Equipment, Policy [Policy Text Block]		Property and Equipment Property and equipment are recorded at cost. Repairs and maintenance costs are expensed as incurred. Depreciation and amortization are calculated using the straight-line method over the estimated useful lives of the assets of three five
Deferred Charges, Policy [Policy Text Block]		Deferred Offering Costs Deferred offering costs, which primarily consist of direct incremental legal and accounting fees relating to the Company’s offerings of equity securities to Lincoln Park, were capitalized. The deferred offering costs were be offset against proceeds from the public offering upon the effectiveness of the public offerings in fiscal 2018. December 31, 2018 2017, zero $464,000 2018
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]		Impairment of Long-Lived Assets The Company reviews long-lived assets, including property and equipment, for impairment whenever events or changes in business circumstances indicate that the carrying amount of the assets may not not December 31, 2018.
Revenue [Policy Text Block]		Revenue Recognition The Company’s revenues are derived from ( 1 2 3 605 10, The Company’s revenue recognition policies generally result in revenue recognition at the following points: 1. Lightbox sales: The Company sells its products directly to hospitals and medical centers. Provided all other criteria for revenue recognition have been met, the Company recognizes revenue for Lightbox sales directly to end customers when delivery and acceptance occurs, which is defined as receipt by the Company of an executed form by the customer acknowledging that the training and installation process is complete. 2. Sales of disposables: Disposable revenues consist of sales of the Company’s catheters and accessories and are recognized when the product has shipped, risk of loss and title has passed to the customer and collectability is reasonably assured. 3. Service revenue: Service revenue is recognized ratably over the term of the service period. To date service revenue has been insignificant. The Company offers its customers the ability to purchase or lease its Lightbox. In addition, the Company provides a Lightbox under a limited commercial evaluation program to allow certain strategic accounts to install and utilize the Lightbox for a limited trial period of three six The Company assessed whether the embedded lease is an operating lease or sales-type lease. Based on the Company’s assessment of the guidance and given that any payments under the lease agreements are dependent upon contingent future sales, it was determined that collectability of the minimum lease payments is not not For sales through distributors, the Company recognizes revenue when title to the product and the risk of loss transfers from the Company to the distributor. The distributors are responsible for all marketing, sales, training and warranty in their respective territories. The standard terms and conditions contained in the Company’s distribution agreements do not not The Company estimates reductions in revenue for potential returns of products by customers. In making such estimates, management analyzes historical returns, current economic trends and changes in customer demand and acceptance of its products. The Company expenses shipping and handling costs as incurred and includes them in the cost of revenues. In those cases where the Company bills shipping and handling costs to customers, it will classify the amounts billed as a component of revenue.
Research and Development Expense, Policy [Policy Text Block]		Research and Development The Company expenses research and development costs as incurred. Research and development expenses include personnel and personnel-related costs, costs associated with pre-clinical and clinical development activities, and costs for prototype products that are manufactured prior to market approval for that prototype product; internal and external costs associated with the Company’s regulatory compliance and quality assurance functions, including the costs of outside consultants and contractors that assist in the process of submitting and maintaining regulatory filings, and overhead costs, including allocated facility and related expenses.
Clinical Trials [Policy Text Block]		Clinical Trials The Company accrues and expenses costs for its clinical trial activities performed by third
Share-based Payment Arrangement [Policy Text Block]		Common Stock Valuation and Stock-Based Compensation Stock-based compensation for the Company includes amortization related to all stock options, restricted stock units (“RSUs”) and shares issued under the employee stock purchase plan (“ESPP”), based on the grant-date estimated fair value. The fair value of stock options is estimated on the date of grant using the Black-Scholes option pricing model and recognized as expense on a straight-line basis over the vesting period of the award. The Company measures the fair value of RSUs using the closing stock price of a share of the Company’s common stock on the grant date and is recognized as expense on a straight-line basis over the vesting period of the award. Because noncash stock-based compensation expense is based on awards ultimately expected to vest, it is reduced by an estimate for future forfeitures. The Company estimates a forfeiture rate for its stock options and RSUs based on an analysis of its actual forfeiture experience and other factors. Forfeitures are estimated at the time of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from estimates. Prior to the Company’s IPO in January 2015, third
Foreign Currency Transactions and Translations Policy [Policy Text Block]		Foreign Currency The Company records net gains and losses resulting from foreign exchange transactions as a component of foreign currency exchange losses in other income (expense), net. During the years ended December 31, 2018 2017, $13,000 $11,000
Income Tax, Policy [Policy Text Block]		Income Taxes The Company utilizes the liability method of accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax reporting bases of assets and liabilities and are measured using enacted tax rates and laws that are expected to be in effect when the differences are expected to reverse. Valuation allowances are established when necessary to reduce deferred tax assets to the amounts expected to be realized. The Company’s policy is to record interest and penalties on uncertain tax positions as income tax expense when they occur. During the years ended December 31, 2018 2017, not
Comprehensive Income, Policy [Policy Text Block]		Comprehensive Loss For the years ended December 31, 2018 2017, no

Note 2 - Summary of Significa_3

Note 2 - Summary of Significant Accounting Policies 1 (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Schedule of Product Warranty Liability [Table Text Block]	Balance at December 31, 2018 $ 272 Warranty provision 70 Usage/release (128 ) Balance at September 30, 2019 $ 214	Year Ended December 31, 2018 2017 Balance, beginning of year $ 390 $ 509 Warranty provision 333 306 Usage/Release (451 ) (425 ) Balance, end of year $ 272 $ 390
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net loss attributable to common stockholders $ (5,518 ) $ (6,224 ) $ (17,014 ) $ (28,766 ) Weighted average common stock outstanding 7,900 1,119 6,189 669 Net loss per share attributable to common stockholders, basic and diluted $ (0.70 ) $ (5.56 ) $ (2.75 ) $ (43.00 )	Year Ended December 31, 2018 2017 Net loss attributable to common stockholders $ (35,692 ) $ (48,732 ) Weighted average common stock outstanding 1,068 65 Net loss per share attributable to common stockholders, basic and diluted $ (33.42 ) $ 749.72 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Common stock warrant equivalents 2,757,741 1,867,226 3,346,568 1,511,832 Common stock options 7,444 8,472 7,596 7,246 Convertible preferred stock 44,923 4,450 45,046 3,969 Unvested restricted stock units 371,651 84,848 316,575 374 3,181,759 1,964,996 3,715,785 1,523,421	Year Ended December 31, 2018 2017 Common stock options 7,179 7,664 Convertible preferred stock 41,398 - Unvested restricted stock units 92,245 508 Common stock warrants 2,077,871 5,371 2,218,693 13,543

Note 4 - Inventories 1 (Tables)

Note 4 - Inventories 1 (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Schedule of Inventory, Current [Table Text Block]	September 30, December 31, 2019 2018 Raw materials $ 1,898 $ 2,102 Work-in-process 544 158 Finished products 1,670 1,162 Total inventories $ 4,112 $ 3,422	December 31, 2018 2017 Raw materials $ 1,162 $ 1,286 Work-in-process 158 - Finished products 2,102 3,009 Total inventories $ 3,422 $ 4,295

Note 5 - Borrowings (Tables)

Note 5 - Borrowings (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Schedule of Debt [Table Text Block]	Year Ending December 31, 2019 (remaining three months of the year) $ — 2020 799 2021 3,403 2022 5,522 2023 3,981 13,705 Less: Amount of PIK additions and final facility fee to be accreted subsequent to September 30, 2019 (4,497 ) Less: Amount representing debt financing costs (630 ) Borrowings, as of September 30, 2019 $ 8,578	Principal and PIK Period Ending December 31, Loan Repayments 2019 $ — 2020 — 2021 — 2022 — 2023 and after 2,000 2,000 Add: PIK 6,243 8,243 Less: Amount representing debt financing costs (757 ) Borrowings, as of December 31, 2018 $ 7,486

Note 6 - Commitments and Cont_2

Note 6 - Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2019
Notes Tables
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	Year Ending December 31, 2019 (remaining three months of the year) $ 418 2020 1,085 2021 1,123 2022 1,162 2023 1,203 Thereafter 1,138 6,128 Less: Imputed interest (937 ) Leasehold liability as of September 30, 2019 $ 5,192

Note 7 - Stockholders' Equity_2

Note 7 - Stockholders' Equity (Deficit) (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]	Expected term (years) 7 Expected volatility 55 % Risk-free interest rate 2 % Dividend rate —	Expected term (years) 7 Expected volatility 55 % Risk-free interest rate 2.0 % Dividend rate —
Share-based Payment Arrangement, Option, Activity [Table Text Block]	Number of Weighted Average Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value Balance at December 31, 2018 7,954 $ 1,707.30 7.69 $ — Options expired (433 ) $ 3,015.01 Options forfeited (105 ) $ 1,929.52 Balance at September 30, 2019 7,416 $ 1,316.32 7.05 $ — Exercisable at September 30, 2019 7,181 $ 1,300.40 7.05 $ — Vested and expected to vest at September 30, 2019 7,416 $ 1,316.32 7.05 $ —	Number of Shares (in thousands) Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value (in thousands) Balance at December 31, 2017 7,664 $ 2,917.30 $ — Options granted 3,100 $ 16.70 Options exercised — $ — Options expired (2,551 ) $ 2,725.80 Options forfeited (259 ) $ 3,493.70 Balance at December 31, 2018 (7,954 ) $ 1,707.30 7.69 $ — Exercisable at December 31, 2018 (4,330 ) $ 2,469.70 6.41 — Vested and expected to vest at December 31, 2018 (7,954 ) $ 1,707.30 7.69 $ —
Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]	Number of Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term Awards outstanding at December 31, 2018 294,066 $ 17.34 3.1 Awarded 764,151 $ 1.24 Released (96,444 ) $ 17.86 Forfeited (20,205 ) $ 20.46 Awards outstanding at September 30, 2019 941,568 $ 4.15 2.0	Weighted Average Weighted Average Grant Date Remaining Number of Fair Contractual Shares Value Term Awards outstanding at December 31, 2017 509 $ 2,377.80 2.87 Awarded 297,753 $ 15.00 Released (128 ) $ 2,739.70 Forfeited (4,068 ) $ 59.70 Awards outstanding at December 31, 2018 294,066 $ 17.34 3.09

Note 8 - Stock-based Compensa_2

Note 8 - Stock-based Compensation (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Cost of revenues $ 40 $ 20 $ 128 $ 56 Research and development expenses 122 137 339 353 Selling, general and administrative expenses 361 611 1,065 1,619 $ 523 $ 768 $ 1,532 $ 2,028	Year Ended December 31, 2018 2017 Cost of revenues $ 97 $ 269 Research and development expenses 547 1,766 Selling, general and administrative expenses 2,436 2,931 $ 3,080 $ 4,966

Note 2 - Summary of Significa_4

Note 2 - Summary of Significant Accounting Policies (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Schedule of Product Warranty Liability [Table Text Block]	Balance at December 31, 2018 $ 272 Warranty provision 70 Usage/release (128 ) Balance at September 30, 2019 $ 214	Year Ended December 31, 2018 2017 Balance, beginning of year $ 390 $ 509 Warranty provision 333 306 Usage/Release (451 ) (425 ) Balance, end of year $ 272 $ 390
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Net loss attributable to common stockholders $ (5,518 ) $ (6,224 ) $ (17,014 ) $ (28,766 ) Weighted average common stock outstanding 7,900 1,119 6,189 669 Net loss per share attributable to common stockholders, basic and diluted $ (0.70 ) $ (5.56 ) $ (2.75 ) $ (43.00 )	Year Ended December 31, 2018 2017 Net loss attributable to common stockholders $ (35,692 ) $ (48,732 ) Weighted average common stock outstanding 1,068 65 Net loss per share attributable to common stockholders, basic and diluted $ (33.42 ) $ 749.72 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Common stock warrant equivalents 2,757,741 1,867,226 3,346,568 1,511,832 Common stock options 7,444 8,472 7,596 7,246 Convertible preferred stock 44,923 4,450 45,046 3,969 Unvested restricted stock units 371,651 84,848 316,575 374 3,181,759 1,964,996 3,715,785 1,523,421	Year Ended December 31, 2018 2017 Common stock options 7,179 7,664 Convertible preferred stock 41,398 - Unvested restricted stock units 92,245 508 Common stock warrants 2,077,871 5,371 2,218,693 13,543

Note 4 - Inventories (Tables)

Note 4 - Inventories (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Schedule of Inventory, Current [Table Text Block]	September 30, December 31, 2019 2018 Raw materials $ 1,898 $ 2,102 Work-in-process 544 158 Finished products 1,670 1,162 Total inventories $ 4,112 $ 3,422	December 31, 2018 2017 Raw materials $ 1,162 $ 1,286 Work-in-process 158 - Finished products 2,102 3,009 Total inventories $ 3,422 $ 4,295

Note 5 - Property and Equipme_2

Note 5 - Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2018
Notes Tables
Property, Plant and Equipment [Table Text Block]	December 31, 2018 2017 Computer software $ 124 $ 248 Computer equipment 197 717 Machinery and equipment 1,784 3,351 Furniture and fixture 78 517 Leasehold improvements 326 638 Equipment held by customers 2,718 2,997 5,227 8,468 Less: Accumulated depreciation and amortization (3,155 ) (5,564 ) Add: Construction-in-progress 6 46 $ 2,078 $ 2,950

Note 6 - Accrued Expenses and_2

Note 6 - Accrued Expenses and Other Current Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
Notes Tables
Schedule of Accrued Liabilities [Table Text Block]	December 31, 2018 2017 Accrued litigation settlement $ - $ 1,760 Accrued interest payable - 364 Accrued sales tax 435 - Accrued professional fees 41 288 Accrued travel expenses 74 90 Accrued product warranty costs 272 390 Accrued clinical trial costs 111 57 Accrued restructuring charge 98 98 Other accrued liabilities 418 550 $ 1,449 $ 3,597

Note 7 - Borrowings (Tables)

Note 7 - Borrowings (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Schedule of Debt [Table Text Block]	Year Ending December 31, 2019 (remaining three months of the year) $ — 2020 799 2021 3,403 2022 5,522 2023 3,981 13,705 Less: Amount of PIK additions and final facility fee to be accreted subsequent to September 30, 2019 (4,497 ) Less: Amount representing debt financing costs (630 ) Borrowings, as of September 30, 2019 $ 8,578	Principal and PIK Period Ending December 31, Loan Repayments 2019 $ — 2020 — 2021 — 2022 — 2023 and after 2,000 2,000 Add: PIK 6,243 8,243 Less: Amount representing debt financing costs (757 ) Borrowings, as of December 31, 2018 $ 7,486

Note 10 - Stockholders' Equit_2

Note 10 - Stockholders' Equity (Deficit) (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]	Expected term (years) 7 Expected volatility 55 % Risk-free interest rate 2 % Dividend rate —	Expected term (years) 7 Expected volatility 55 % Risk-free interest rate 2.0 % Dividend rate —
Share-based Payment Arrangement, Option, Activity [Table Text Block]	Number of Weighted Average Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value Balance at December 31, 2018 7,954 $ 1,707.30 7.69 $ — Options expired (433 ) $ 3,015.01 Options forfeited (105 ) $ 1,929.52 Balance at September 30, 2019 7,416 $ 1,316.32 7.05 $ — Exercisable at September 30, 2019 7,181 $ 1,300.40 7.05 $ — Vested and expected to vest at September 30, 2019 7,416 $ 1,316.32 7.05 $ —	Number of Shares (in thousands) Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value (in thousands) Balance at December 31, 2017 7,664 $ 2,917.30 $ — Options granted 3,100 $ 16.70 Options exercised — $ — Options expired (2,551 ) $ 2,725.80 Options forfeited (259 ) $ 3,493.70 Balance at December 31, 2018 (7,954 ) $ 1,707.30 7.69 $ — Exercisable at December 31, 2018 (4,330 ) $ 2,469.70 6.41 — Vested and expected to vest at December 31, 2018 (7,954 ) $ 1,707.30 7.69 $ —
Share-based Payment Arrangement, Option, Exercise Price Range [Table Text Block]		Options Outstanding Options Vested Weighted Average Weighted Weighted Options Remaining Average Number Average Exercise Outstanding Contractual Exercise Exercisable Exercise Price (in thousands) Life Price (in thousands) Price $ 16.70 3,100 9.44 $ 16.70 — $ 16.70 $ 204.00 5 8.56 $ 204.00 2 $ 204.00 $ 820.00 798 8.21 $ 820.00 679 $ 820.00 $ 1,052.00 47 8.18 $ 1,052.00 25 $ 1,052.00 $ 1,420.00 69 7.84 $ 1,420.00 69 $ 1,420.00 $ 1,472.00 11 7.80 $ 1,472.00 6 $ 1,472.00 $ 1,620.00 7 0.44 $ 1,620.00 7 $ 1,620.00 $ 1,800.00 2,704 5.99 $ 1,800.00 2,704 $ 1,800.00 $ 1,980.00 25 1.33 $ 1,980.00 25 $ 1,980.00 $ 4,364.00 10 6.18 $ 4,364.00 9 $ 4,364.00 $ 4,404.00 23 7.44 $ 4,404.00 23 $ 4,404.00 $ 4,952.00 18 7.33 $ 4,952.00 12 $ 4,952.00 $ 5,040.00 104 2.57 $ 5,040.00 104 $ 5,040.00 $ 5,184.00 150 7.19 $ 5,184.00 103 $ 5,184.00 $ 5,196.00 301 7.17 $ 5,196.00 236 $ 5,196.00 $ 5,940.00 11 2.74 $ 5,940.00 11 $ 5,940.00 $ 6,084.00 11 6.58 $ 6,084.00 9 $ 6,084.00 $ 7,844.00 118 6.89 $ 7,844.00 92 $ 7,844.00 $ 8,100.00 379 7.22 $ 8,100.00 186 $ 8,100.00 $ 8,820.00 63 8.20 $ 8,820.00 28 $ 8,820.00 7,954 7.69 $ 1,707.57 4,330 $ 2,470.67
Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]	Number of Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term Awards outstanding at December 31, 2018 294,066 $ 17.34 3.1 Awarded 764,151 $ 1.24 Released (96,444 ) $ 17.86 Forfeited (20,205 ) $ 20.46 Awards outstanding at September 30, 2019 941,568 $ 4.15 2.0	Weighted Average Weighted Average Grant Date Remaining Number of Fair Contractual Shares Value Term Awards outstanding at December 31, 2017 509 $ 2,377.80 2.87 Awarded 297,753 $ 15.00 Released (128 ) $ 2,739.70 Forfeited (4,068 ) $ 59.70 Awards outstanding at December 31, 2018 294,066 $ 17.34 3.09

Note 11 - Stock-based Compens_2

Note 11 - Stock-based Compensation (Tables)	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Notes Tables
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2019 2018 2019 2018 Cost of revenues $ 40 $ 20 $ 128 $ 56 Research and development expenses 122 137 339 353 Selling, general and administrative expenses 361 611 1,065 1,619 $ 523 $ 768 $ 1,532 $ 2,028	Year Ended December 31, 2018 2017 Cost of revenues $ 97 $ 269 Research and development expenses 547 1,766 Selling, general and administrative expenses 2,436 2,931 $ 3,080 $ 4,966

Note 12 - Income Taxes (Tables)

Note 12 - Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Notes Tables
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Year Ended December 31, 2018 2017 Tax at federal statutory rate $ (5,787 ) $ (16,565 ) Federal Tax rate remeasurement — 35,953 State taxes, net of federal benefit (1,023 ) 993 Permanent differences 228 525 Change in valuation allowance 6,582 (22,554 ) Research credits — (229 ) Other — 1,877 Provision for taxes $ — $ —
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	As of December 31, 2018 2017 Deferred tax assets/(liabilities): Federal, state and foreign net operating losses $ 70,286 $ 62,057 Research and other credits 3,655 3,632 Fixed assets (176 ) 604 Accruals and other 4,317 4,208 Total net deferred tax assets 78,082 70,501 Less: Valuation allowance (78,082 ) (70,501 ) Net deferred tax assets $ — $ —
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]	As of December 31, 2018 2017 Balance at beginning of year $ 1,747 $ 1,536 Increase based on the tax positions in the current year 29 211 Decrease for tax positions of prior year (16 ) — Balance at end of year $ 1,760 $ 1,747

Note 1 - Organization (Details

Note 1 - Organization (Details Textual) - USD ($)	Aug. 26, 2019	Aug. 01, 2019	Nov. 01, 2018	Jul. 16, 2018	Jul. 13, 2018	Jul. 12, 2018	Feb. 16, 2018	Feb. 14, 2018	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retained Earnings (Accumulated Deficit), Ending Balance										$ (343,214,000)		$ (328,885,000)	$ (301,327,000)
Cash and Cash Equivalents, at Carrying Value, Ending Balance									$ 10,008,000	14,461,000	$ 10,008,000	$ 16,410,000	$ 5,389,000	$ 36,096,000
Proceeds from Issuance or Sale of Equity, Net		$ 3,800,000	$ 10,200,000		$ 3	$ 3,000,000	$ 15,500,000			$ 8,000,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							1,797,900
Preferred Stock, Par or Stated Value Per Share							$ 0.001			$ 0.001		$ 0.001	$ 0.001
Debt Conversion, Original Debt, Amount											$ 38,000,000	$ 42,794,000
Share Price										$ 0.83		$ 3
Common Stock [Member]
Stock Issued During Period, Shares, New Issues			728,500						216,618	3,813,559			23,452
Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]
Sale of Stock, Consideration Received on Transaction				$ 3,000,000		$ 3,000,000
Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member] | Common Stock [Member]
Stock Issued During Period, Shares, New Issues					216,618	216,618					216,618	216,618
Shares Issued, Price Per Share						$ 16.425	$ 15.80
November Public Offering [Member] | Common Stock [Member]
Stock Issued During Period, Shares, New Issues			728,500									728,500
August Public Offering [Member] | Common Stock [Member]
Proceeds from Issuance or Sale of Equity, Net	$ 3,800,000
Stock Issued During Period, Shares, New Issues	3,813,559
Share Price	$ 1.18
CRG [Member] | Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member]
Debt Conversion, Original Debt, Amount							$ 38,000,000	$ 38,000,000
Debt Conversion, Converted Instrument, Amount							$ 41,800,000	$ 41,800,000
Common Stock Warrants, Issued with Series B Preferred Stock, Warrant One [Member]
Class of Warrant or Right, Number of Warrants Issued for Each Share of Preferred Stock							1
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right							50
Class of Warrant or Right, Contingent Expiration Period Following Initial Exercise Date							7 years
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 4
Common Stock Warrants, Issued with Series B Preferred Stock, Warrant Two [Member]
Class of Warrant or Right, Number of Warrants Issued for Each Share of Preferred Stock							1
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right							50
Class of Warrant or Right, Contingent Expiration Period Following Initial Exercise Date							7 years
Class of Warrant or Right, Expiration Period Following FDA Clearance							60 days
Common Stock Warrants [Member] | Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]
Stock Issued During Period, Shares, New Issues				216,618
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				108,309	108,309	108,309						108,309
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right				1		1
Shares Issued, Price Per Share				$ 16.425
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 15.80	$ 15.80	$ 15.80
Common Stock Warrants [Member] | November Public Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			2,875,000							876,840
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right			1
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 4
Series B Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues							17,979
Preferred Stock, Par or Stated Value Per Share							$ 0.001
Series A Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues							41,800
Series A Preferred Stock [Member] | Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member]
Convertible Preferred Stock, Shares of Common Stock Issuable on Conversion							2,090,000	2,090,000
Series C Preferred Stock [Member]
Proceeds from Issuance or Sale of Equity, Net			$ 10,200,000
Stock Issued During Period, Shares, New Issues			8,586
Preferred Stock, Par or Stated Value Per Share			$ 0.001
Series C Preferred Stock [Member] | November Public Offering [Member]
Proceeds from Issuance or Sale of Equity, Net			$ 10,200,000
Stock Issued During Period, Shares, New Issues			8,586

Note 2 - Summary of Significa_5

Note 2 - Summary of Significant Accounting Policies 1 (Details Textual) shares in Thousands	Jun. 19, 2019	Jan. 30, 2018	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)shares	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)shares	Apr. 01, 2019USD ($)	Jan. 01, 2019USD ($)
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax, Total			$ 0		$ 0		$ 0	$ 0
Warranty Period					1 year		1 year
Weighted Average Number of Shares, Common Stock Subject to Repurchase or Cancellation | shares					0		0	0
Number of Operating Segments					1
Operating Lease, Right-of-Use Asset			5,192,000		$ 5,192,000				$ 6,000,000
Operating Lease, Liability, Total			5,192,000		5,192,000				$ 6,000,000
Other Nonoperating Income (Expense), Total			$ 299,000	$ 242,000	$ 868,000	$ 710,000	$ (13,000)	$ 11,000
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset										$ 1,800,000
Operating Lease, Liability, Total										$ 1,800,000
Operating Leases, Rent Expense, Sublease Rentals				(240,000)		720,000
Other Nonoperating Income (Expense), Total				$ 240,000		$ 720,000
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Number of Major Customers					0		0	0
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Number of Major Customers			0	0	0	0	0	0
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | UNITED STATES
Concentration Risk, Percentage			96.00%	94.00%	94.00%	94.00%	94.00%	95.00%
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	10	40

Note 2 - Summary of Significa_6

Note 2 - Summary of Significant Accounting Policies - Product Warranty Costs (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance	$ 272	$ 390	$ 509
Warranty provision	70	333	306
Usage/release	(128)	(451)	(425)
Balance	$ 214	$ 272	$ 390

Note 2 - Summary of Significa_7

Note 2 - Summary of Significant Accounting Policies - Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Net loss attributable to common stockholders	$ (5,518)	$ (6,224)	$ (17,014)	$ (28,766)	$ (35,692)	$ (48,732)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	7,900	1,119	6,189	669	1,068	65
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.70)	$ (5.56)	$ (2.75)	$ (43)	$ (33.42)	$ (749.72)

Note 2 - Summary of Significa_8

Note 2 - Summary of Significant Accounting Policies - Anti-dilutive Securities (Details) - shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities (in shares)	3,181,759	1,964,996	3,715,785	1,523,421	2,218,693	13,543
Common Stock Warrants [Member]
Antidilutive Securities (in shares)	2,757,741	1,867,226	3,346,568	1,511,832	2,077,871	5,371
Common Stock Options [ member]
Antidilutive Securities (in shares)	7,444	8,472	7,596	7,246	7,179	7,664
Preferred Stock [Member]
Antidilutive Securities (in shares)	44,923	4,450	45,046	3,969	41,398
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities (in shares)	371,651	84,848	316,575	374	92,245	508

Note 3 - Fair Value Measureme_3

Note 3 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure	$ 0	$ 0	$ 0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure	0	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 0	$ 0	$ 0

Note 4 - Inventories - Schedule

Note 4 - Inventories - Schedule of Inventory (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Raw materials	$ 1,898	$ 2,102	$ 1,286
Work-in-process	544	158
Finished products	1,670	1,162	3,009
Total inventories	$ 4,112	$ 3,422	$ 4,295

Note 5 - Borrowings (Details Te

Note 5 - Borrowings (Details Textual)	Feb. 14, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2021USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2023USD ($)	Dec. 31, 2022USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Jan. 24, 2018USD ($)	Jan. 01, 2018USD ($)	Jun. 15, 2016USD ($)	Sep. 22, 2015USD ($)
Line of Credit Facility, Maximum Borrowing Capacity														$ 50,000,000
Debt Conversion, Original Debt, Amount						$ 38,000,000			$ 42,794,000
Debt Instrument, Redemption Initial Prepayment Premium Percentage														5.00%
Debt Instrument, Redemption Annual Decline in Prepayment Premium Percentage														1.00%
Debt Instrument, Redemption Prepayment Premium Percentage after Fifth Year														0.00%
Debt Instrument, Financing Fee Percentage														1.50%
Debt Instrument, Final Facility Fee Percentage	15.00%													7.00%
Debt Instrument, Covenant Compliance Cash and Certain Cash Equivalents Minimum	$ 3,500,000										$ 50,000,000	$ 2,500,000		$ 5,000,000
Debt Instrument, Covenant Compliance Prepayment Multiplier for Revenue Shortfall														2
Debt Instrument, Covenant Compliance Target Minimum Revenue Sixth Year	15,000,000
Debt Instrument, Covenant Compliance Target Minimum Revenue Seventh Year	20,000,000
Debt Instrument, Covenant Compliance Target Minimum Revenue Eighth Year	25,000,000
Interest Expense, Total		$ 377,000	$ 324,000		1,091,000	5,358,000			5,692,000	6,299,000
CRG [Member] | Loan Agreement [Member] | Forecast [Member]
Debt Instrument, Periodic Payment, Principal				$ 1,200,000
Debt Instrument, Periodic Payment, Total				$ 2,400,000			$ 2,400,000	$ 4,800,000
CRG [Member] | Loan Agreement [Member] | Series A Preferred Stock Purchase Agreement with CRG [Member]
Debt Conversion, Original Debt, Amount	38,000,000
Debt Conversion, Fees and Prepayment Premium Amount	$ 3,800,000
Debt Instrument, Interest Rate, Stated Percentage														12.50%
CRG [Member] | Loan Agreement [Member]
Debt Instrument, Face Amount									2,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net, Total		630,000			630,000				757,000	716,000			$ 154,000	$ 1,300,000
Amortization of Debt Discount (Premium)		42,000	30,000		127,000	84,000			$ 117,000	$ 203,000
Interest Expense, Total		$ 377,000	$ 362,000		$ 1,100,000	$ 5,400,000
CRG [Member] | Loan Agreement [Member] | First Tranche, Borrowed on September 22, 2015 [Member]
Debt Instrument, Face Amount														30,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net, Total														$ 876,000
CRG [Member] | Loan Agreement [Member] | Second Tranche, Borrowed on June 15, 2016 [Member]
Debt Instrument, Face Amount													10,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net, Total													$ 275,000

Note 5 - Borrowings - Schedule

Note 5 - Borrowings - Schedule of Debt (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 15, 2016	Sep. 22, 2015
2020
2021
2022
Borrowings, as of September 30, 2019	$ 8,578,000	7,486,000	$ 44,744,000
CRG [Member] | Loan Agreement [Member]
2019 (remaining three months of the year)
2020	799,000
2021	3,403,000
2022	5,522,000
2023	3,981,000
	13,705,000	8,243,000
Less: Amount of PIK additions and final facility fee to be accreted subsequent to September 30, 2019	(4,497,000)	6,243,000
Less: Amount representing debt financing costs	(630,000)	(757,000)	$ (716,000)	$ (154,000)	$ (1,300,000)
Borrowings, as of September 30, 2019	$ 8,578,000	$ 7,486,000

Note 6 - Commitments and Cont_3

Note 6 - Commitments and Contingencies (Details Textual)	Dec. 01, 2017USD ($)	May 25, 2017	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2019USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2018USD ($)	Apr. 01, 2019USD ($)	Jan. 01, 2019USD ($)
Operating Lease, Right-of-Use Asset			$ 5,192,000		$ 5,192,000			$ 6,000,000
Operating Lease, Liability, Total			5,192,000		5,192,000			$ 6,000,000
Lessee, Operating Lease, Term of Contract								5 years
Lessee, Operating Lease, Liability, Payments, Due, Total			6,128,000		6,128,000			$ 5,800,000
Lessee, Operating Lease, Discount Rate								6.50%
Operating Lease, Expense			314,000	$ 481,000	1,100,000	$ 1,400,000
Operating Lease, Right-of-Use Asset, Amortization			225,000		444,000
Prepaid Rent			358,000		358,000
Class Action Lawsuits Related to IPO [Member] | Pending Litigation [Member]
Loss Contingency, New Claims Filed, Number		3
Loss Contingency Accrual, Payments							1,760,000
Class Action Lawsuits Related to IPO [Member] | Settled Litigation [Member]
Litigation Settlement, Amount Awarded to Other Party from All Defendants							5,000,000
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset									$ 1,800,000
Operating Lease, Liability, Total									$ 1,800,000
Facility Lease [Member]
Incentive from Lessor			$ 369,000		$ 369,000		$ 369,000
Facility Sublease [Member]
Operating Leases Sublease Expiration Prior to Base Lease	15 days
Operating Leases, Monthly Minimum Sublease Rental Payments Receivable Final	$ 82,410

Note 6 - Commitments and Cont_4

Note 6 - Commitments and Contingencies - Future Operating Lease Payments (Details) - USD ($)	Sep. 30, 2019	Apr. 01, 2019
2019 (remaining three months of the year)	$ 418,000
2020	1,085,000
2021	1,123,000
2022	1,162,000
2023	1,203,000
Thereafter	1,138,000
	6,128,000	$ 5,800,000
Less: Imputed interest	(937,000)
Leasehold liability as of September 30, 2019	$ 5,192,000	$ 6,000,000

Note 7 - Stockholders' Equity_3

Note 7 - Stockholders' Equity (Deficit) (Details Textual) - USD ($)	Aug. 01, 2019	Jun. 19, 2019	Nov. 01, 2018	Jul. 16, 2018	Jul. 13, 2018	Jul. 12, 2018	Feb. 16, 2018	Feb. 14, 2018	Jan. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Aug. 28, 2019	Aug. 22, 2018	Jan. 31, 2015
Preferred Stock, Shares Authorized										5,000,000			5,000,000		5,000,000	5,000,000
Preferred Stock, Par or Stated Value Per Share							$ 0.001			$ 0.001			$ 0.001		$ 0.001	$ 0.001
Preferred Stock, Shares Issued, Total										44,923			44,923		45,671	0
Debt Conversion, Original Debt, Amount														$ 38,000,000	$ 42,794,000
Preferred Stock, Shares Outstanding, Ending Balance										44,923			44,923		45,671	0
Proceeds from Issuance or Sale of Equity, Net	$ 3,800,000		$ 10,200,000		$ 3	$ 3,000,000	$ 15,500,000						$ 8,000,000
Preferred Stock Deemed Dividend Arising from Beneficial Conversion Feature														5,216,000	$ 5,216,000
Common Stock, Shares Authorized										100,000,000			100,000,000		100,000,000	100,000,000
Common Stock, Par or Stated Value Per Share										$ 0.001			$ 0.001		$ 0.001	$ 0.001
Common Stock, Shares, Outstanding, Ending Balance										10,342,179			10,342,179		3,492,200	83,360
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							1,797,900
Class of Warrant or Right, Outstanding										2,753,999			2,753,999		4,757,539	5,380
Proceeds from Warrant Exercises													$ 7,993,000	581,000	$ 581,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period													4 years		4 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period													10 years		10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period													0		0
Share-based Payment Arrangement, Expense, Tax Benefit										$ 0	$ 0		$ 0	0	$ 0	$ 0
Share Price										$ 0.83			$ 0.83		$ 3
Common Stock, Shares, Issued, Total										10,342,179			10,342,179		3,492,200	83,360
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total										$ 142,000			$ 142,000		$ 430,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition													1 year		1 year 109 days
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total										$ 3,600,000			$ 3,600,000		$ 4,300,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition													2 years		2 years 182 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance										941,568			941,568		294,066	509
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Fair Value										$ 782,000			$ 782,000		$ 900,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value													$ 110,000	$ 1,000	$ 1,500	$ 97,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value													$ 1.24	$ 15.80	$ 15	$ 1,144.10
Minimum [Member] | Common Stock Options [ member]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent													100.00%		100.00%
Minimum [Member] | Common Stock Options [ member] | Stockholder with More than 10% Voting Power [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent												110.00%			110.00%
Minimum [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period													3 years		3 years
Maximum [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period													4 years		4 years
The 2015 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized																			3,300
Share-based Compensation Arrangement by Share-based Payment Award, Additional Shares Reserved for Issuance, Annual																			4,225
Share-based Compensation Arrangement by Share-based Payment Award, Additional Shares Reserved for Issuance, Percentage on Shares Outstanding																			5.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized		800,000													300,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant										68,954			68,954		12,668
Officer and Director Share Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized																	40,000	20,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant										37,056			37,056
Stock Issued During Period, Shares, Employee Stock Purchase Plans													18,543		4,401
Common Stock Warrants, Issued with Series E Convertible Preferred Stock [Member]
Class of Warrant or Right, Securities Called as Percentage of Convertible Preferred Stock Shares										50.00%			50.00%		50.00%
Class of Warrant or Right, Number of Securities Called by Warrants or Rights												5,380
Class of Warrant or Right, Exercise Price of Warrants or Rights												$ 5,040			$ 5,040
Class of Warrant or Right, Outstanding															5,380
Common Stock Warrants, Issued with Series B Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							1,797,900			1,768,850			1,768,850		1,768,850
Common Stock Warrants, Issued with Series B Preferred Stock, Warrant One [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 4
Class of Warrant or Right, Number of Warrants Issued for Each Share of Preferred Stock							1
Class of Warrant or Right, Contingent Expiration Period Following Initial Exercise Date							7 years
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right							50
Common Stock Warrants, Issued with Series B Preferred Stock, Warrant Two [Member]
Class of Warrant or Right, Number of Warrants Issued for Each Share of Preferred Stock							1
Class of Warrant or Right, Contingent Expiration Period Following Initial Exercise Date							7 years
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right							50
Class of Warrant or Right, Expiration Period Following FDA Clearance							60 days
Common Stock Warrants [Member] | Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]
Stock Issued During Period, Shares, New Issues				216,618
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				108,309	108,309	108,309									108,309
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 15.80	$ 15.80	$ 15.80
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right				1		1
Common Stock Warrants [Member] | November Public Offering [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			2,875,000							876,840			876,840
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 4
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right			1
Class of Warrant or Right, Outstanding															28,750,000
Class of Warrant or Right, Exercised													1,998,079
Proceeds from Warrant Exercises													$ 8,000,000
Preferred Stock Warrants [Member] | November Public Offering [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right			250
Common Stock [Member]
Stock Issued During Period, Shares, New Issues			728,500								216,618		3,813,559			23,452
Stock Issued During Period, Shares, Employee Stock Purchase Plans										10,947	209		18,735	209	4,401
Common Stock [Member] | Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]
Stock Issued During Period, Shares, New Issues					216,618	216,618								216,618	216,618
Common Stock [Member] | November Public Offering [Member]
Stock Issued During Period, Shares, New Issues			728,500												728,500
Conversion of Series B Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted													1,523
Conversion of Stock, Shares Issued													380,750
Conversion of Series B Preferred Stock into Common Stock [Member] | Common Stock [Member]
Conversion of Stock, Shares Issued															813,900
Conversion of Series C Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted													2,170
Conversion of Stock, Shares Issued													542,500
Conversion of Series C Preferred Stock into Common Stock [Member] | Common Stock [Member]
Conversion of Stock, Shares Issued															1,604,000
Series A Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance										44,745			44,745		41,800
Dividends, Preferred Stock, Total										$ 895,000	$ 836,000		$ 2,700,000	$ 2,100,000
Stock Issued During Period, Shares, New Issues							41,800
Series A Preferred Stock [Member] | CRG [Member]
Preferred Stock Dividends, Shares									2,945
Series B Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share							$ 0.001
Preferred Stock, Shares Outstanding, Ending Balance										178			178		1,701
Stock Issued During Period, Shares, New Issues							17,979
Preferred Stock Deemed Dividend Arising from Beneficial Conversion Feature							$ 5,200,000
Series B Preferred Stock [Member] | Conversion of Series B Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted															16,278
Series C Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share			$ 0.001
Preferred Stock, Shares Outstanding, Ending Balance															2,170
Stock Issued During Period, Shares, New Issues			8,586
Proceeds from Issuance or Sale of Equity, Net			$ 10,200,000
Series C Preferred Stock [Member] | November Public Offering [Member]
Stock Issued During Period, Shares, New Issues			8,586
Proceeds from Issuance or Sale of Equity, Net			$ 10,200,000
Series C Preferred Stock [Member] | Conversion of Series C Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted															6,416
Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Convertible Preferred Stock, Shares of Common Stock Issuable on Conversion							2,090,000	2,090,000
Preferred Stock, Dividend Rate, Percentage								8.00%
CRG [Member] | Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member]
Debt Conversion, Original Debt, Amount							$ 38,000,000	$ 38,000,000
Debt Conversion, Fees and Prepayment Premium Amount								3,800,000
Debt Conversion, Converted Instrument, Amount							$ 41,800,000	$ 41,800,000

Note 7 - Stockholders' Equity_4

Note 7 - Stockholders' Equity (Deficit) - Assumptions Used to Estimate Fair Value (Details)	Dec. 31, 2018	Feb. 28, 2018
Measurement Input, Expected Term [Member]
Measurement input	7	7
Measurement Input, Price Volatility [Member]
Measurement input	0.55	0.55
Measurement Input, Risk Free Interest Rate [Member]
Measurement input	0.02	0.02
Measurement Input, Expected Dividend Rate [Member]
Measurement input

Note 7 - Stockholders' Equity_5

Note 7 - Stockholders' Equity (Deficit) - Stock Option Activity (Details) - $ / shares shares in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Options (in shares)	7,954	7,664
Options, weighted average exercise price (in dollars per share)	$ 1,707.30	$ 2,917.30
Options, weighted average remaining contractual life (Year)	7 years 18 days	7 years 251 days
Options expired (in shares)	(433)	(2,551)
Options expired, weighted average exercise price (in dollars per share)	$ 3,015.01	$ 2,725.80
Options forfeited (in shares)	(105)	(259)
Options forfeited, weighted average exercise price (in dollars per share)	$ 1,929.52	$ 3,493.70
Options (in shares)	7,416	7,954
Options, weighted average exercise price (in dollars per share)	$ 1,316.32	$ 1,707.30
Exercisable (in shares)	7,181	4,330
Exercisable, weighted average exercise price (in dollars per share)	$ 1,300.40	$ 2,469.70
Exercisable, weighted average remaining contractual life (Year)	7 years 18 days	6 years 149 days
Vested and expected to vest (in shares)	7,416	7,954
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 1,316.32	$ 1,707.30
Vested and expected to vest, weighted average remaining contractual life (Year)	7 years 18 days	7 years 251 days

Note 7 - Stockholders' Equity_6

Note 7 - Stockholders' Equity (Deficit) - Restricted Stock Units Award Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Awards outstanding, Shares (in shares)	294,066	509	509
Awards outstanding, Weighted grant date fair value (in dollars per share)	$ 17.34	$ 2,377.80	$ 2,377.80
Awards outstanding, Weighted average remaining contractual term (Year)	2 years		3 years 36 days	2 years 317 days
Awarded, Shares (in shares)	764,151		297,753
Awarded, Weighted grant date fair value (in dollars per share)	$ 1.24	$ 15.80	$ 15	$ 1,144.10
Released, Shares (in shares)	(96,444)		(128)
Released, Weighted grant date fair value (in dollars per share)	$ 17.86		$ 2,739.70
Forfeited, Shares (in shares)	(20,205)		(4,068)
Forfeited, Weighted grant date fair value (in dollars per share)	$ 20.46		$ 59.70
Awards outstanding, Shares (in shares)	941,568		294,066	509
Awards outstanding, Weighted grant date fair value (in dollars per share)	$ 4.15		$ 17.34	$ 2,377.80

Note 8 - Stock-based Compensa_3

Note 8 - Stock-based Compensation - Noncash Stock-based Compensation Expense Related to Stock Options, ESPP, and RSUs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Allocated Share-based Compensation Expense	$ 523	$ 768	$ 1,532	$ 2,028	$ 3,080	$ 4,966
Cost of Sales [Member]
Allocated Share-based Compensation Expense	40	20	128	56	97	269
Research and Development Expense [Member]
Allocated Share-based Compensation Expense	122	137	339	353	547	1,766
Selling, General and Administrative Expenses [Member]
Allocated Share-based Compensation Expense	$ 361	$ 611	$ 1,065	$ 1,619	$ 2,436	$ 2,931

Note 1 - Organization (Detail_2

Note 1 - Organization (Details Textual) - USD ($)	Aug. 01, 2019	Nov. 01, 2018	Jul. 16, 2018	Jul. 13, 2018	Jul. 12, 2018	Feb. 16, 2018	Feb. 14, 2018	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Feb. 03, 2016
Retained Earnings (Accumulated Deficit), Ending Balance									$ (343,214,000)		$ (328,885,000)	$ (301,327,000)
Cash and Cash Equivalents, at Carrying Value, Ending Balance								$ 10,008,000	14,461,000	$ 10,008,000	16,410,000	5,389,000	$ 36,096,000
Proceeds from Issuance or Sale of Equity, Net	$ 3,800,000	$ 10,200,000		$ 3	$ 3,000,000	$ 15,500,000			8,000,000
Common Stock Offering, Maximum Aggregate Value														$ 150,000,000
Proceeds from Issuance of Common Stock											314,000	246,000
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						1,797,900
Debt Conversion, Original Debt, Amount										$ 38,000,000	$ 42,794,000
Preferred Stock, Par or Stated Value Per Share						$ 0.001			$ 0.001		$ 0.001	$ 0.001
CRG [Member] | Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member]
Debt Conversion, Original Debt, Amount						$ 38,000,000	$ 38,000,000
Debt Conversion, Converted Instrument, Amount						$ 41,800,000	$ 41,800,000
Common Stock Warrants, Issued with Series B Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						1,797,900			1,768,850		1,768,850
Common Stock Warrants, Issued with Series B Preferred Stock, Warrant One [Member]
Class of Warrant or Right, Number of Warrants Issued for Each Share of Preferred Stock						1
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right						50
Class of Warrant or Right, Contingent Expiration Period Following Initial Exercise Date						7 years
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 4
Common Stock Warrants, Issued with Series B Preferred Stock, Warrant Two [Member]
Class of Warrant or Right, Number of Warrants Issued for Each Share of Preferred Stock						1
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right						50
Class of Warrant or Right, Contingent Expiration Period Following Initial Exercise Date						7 years
Class of Warrant or Right, Expiration Period Following FDA Clearance						60 days
Series B Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues						17,979
Preferred Stock, Par or Stated Value Per Share						$ 0.001
Series A Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues						41,800
Series A Preferred Stock [Member] | Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member]
Convertible Preferred Stock, Shares of Common Stock Issuable on Conversion						2,090,000	2,090,000
Series C Preferred Stock [Member]
Proceeds from Issuance or Sale of Equity, Net		$ 10,200,000
Stock Issued During Period, Shares, New Issues		8,586
Preferred Stock, Par or Stated Value Per Share		$ 0.001
Common Stock [Member]
Stock Issued During Period, Shares, New Issues		728,500						216,618	3,813,559			23,452
Sales Agreement with Cowen [Member]
Common Stock Offering, Maximum Aggregate Value														$ 50,000,000
Proceeds from Issuance of Common Stock												$ 3,187,000	5,171,000
Underwriting Discount and Commissions												$ 101,000	$ 160,000
Sales Agreement with Cowen [Member] | Common Stock [Member]
Stock Issued During Period, Shares, New Issues												18,968	2,737
Shares Issued, Price Per Share												$ 176.80	$ 1,947.40
Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]
Sale of Stock, Consideration Received on Transaction			$ 3,000,000		$ 3,000,000
Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member] | Common Stock Warrants [Member]
Stock Issued During Period, Shares, New Issues			216,618
Shares Issued, Price Per Share			$ 16.425
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			108,309	108,309	108,309						108,309
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right			1		1
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 15.80	$ 15.80	$ 15.80
Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member] | Common Stock [Member]
Stock Issued During Period, Shares, New Issues				216,618	216,618					216,618	216,618
Shares Issued, Price Per Share					$ 16.425	$ 15.80
November Public Offering [Member] | Common Stock Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		2,875,000							876,840
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right		1
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 4
November Public Offering [Member] | Series C Preferred Stock [Member]
Proceeds from Issuance or Sale of Equity, Net		$ 10,200,000
Stock Issued During Period, Shares, New Issues		8,586
November Public Offering [Member] | Common Stock [Member]
Stock Issued During Period, Shares, New Issues		728,500									728,500

Note 2 - Summary of Significa_9

Note 2 - Summary of Significant Accounting Policies (Details Textual) shares in Thousands	Jun. 19, 2019	Jan. 30, 2018	Sep. 30, 2019USD ($)	Sep. 30, 2018	Sep. 30, 2019USD ($)shares	Sep. 30, 2018	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)shares	Apr. 01, 2019USD ($)	Jan. 01, 2019USD ($)
Available-for-sale Securities, Accumulated Gross Unrealized Gain (Loss), before Tax, Total			$ 0		$ 0		$ 0	$ 0
Deferred Offering Costs							0	464,000
Impairment of Long-Lived Assets Held-for-use							$ 0
Warranty Period					1 year		1 year
Foreign Currency Transaction Gain (Loss), before Tax, Total							$ (13,000)	11,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total							$ 0	$ 0
Weighted Average Number of Shares, Common Stock Subject to Repurchase or Cancellation | shares					0		0	0
Number of Reportable Segments							1
Operating Lease, Right-of-Use Asset			5,192,000		$ 5,192,000				$ 6,000,000
Operating Lease, Liability, Total			$ 5,192,000		$ 5,192,000				$ 6,000,000
Accounting Standards Update 2016-02 [Member]
Operating Lease, Right-of-Use Asset										$ 1,800,000
Operating Lease, Liability, Total										1,800,000
Accounting Standards Update 2016-02 [Member] | Subsequent Event [Member]
Operating Lease, Right-of-Use Asset										1,800,000
Operating Lease, Liability, Total										$ 1,800,000
Minimum [Member]
Property, Plant and Equipment, Useful Life							3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life							5 years
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Number of Major Customers					0		0	0
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Number of Major Customers			0	0	0	0	0	0
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | UNITED STATES
Concentration Risk, Percentage			96.00%	94.00%	94.00%	94.00%	94.00%	95.00%
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	10	40

Note 2 - Summary of Signific_10

Note 2 - Summary of Significant Accounting Policies - Product Warranty (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Balance	$ 272	$ 390	$ 509
Warranty provision	70	333	306
Usage/release	(128)	(451)	(425)
Balance	$ 214	$ 272	$ 390

Note 2 - Summary of Signific_11

Note 2 - Summary of Significant Accounting Policies - Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Net loss attributable to common stockholders	$ (5,518)	$ (6,224)	$ (17,014)	$ (28,766)	$ (35,692)	$ (48,732)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	7,900	1,119	6,189	669	1,068	65
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.70)	$ (5.56)	$ (2.75)	$ (43)	$ (33.42)	$ (749.72)

Note 2 - Summary of Signific_12

Note 2 - Summary of Significant Accounting Policies - Antidilutive Securities (Details) - shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Antidilutive Securities (in shares)	3,181,759	1,964,996	3,715,785	1,523,421	2,218,693	13,543
Common Stock Options [ member]
Antidilutive Securities (in shares)	7,444	8,472	7,596	7,246	7,179	7,664
Preferred Stock [Member]
Antidilutive Securities (in shares)	44,923	4,450	45,046	3,969	41,398
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities (in shares)	371,651	84,848	316,575	374	92,245	508
Common Stock Warrants [Member]
Antidilutive Securities (in shares)	2,757,741	1,867,226	3,346,568	1,511,832	2,077,871	5,371

Note 3 - Fair Value Measureme_4

Note 3 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure	$ 0	$ 0	$ 0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	0	0	0
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure	0	0	0
Financial and Nonfinancial Liabilities, Fair Value Disclosure	$ 0	$ 0	$ 0

Note 4 - Inventories - Schedu_2

Note 4 - Inventories - Schedule of Inventories (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Raw materials	$ 1,898	$ 2,102	$ 1,286
Work-in-process	544	158
Finished products	1,670	1,162	3,009
Total inventories	$ 4,112	$ 3,422	$ 4,295

Note 5 - Property and Equipme_3

Note 5 - Property and Equipment, Net (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2019
Depreciation, Total	$ 934,000	$ 1,476,000
Property, Plant and Equipment, Net, Ending Balance	2,078,000	2,950,000	$ 1,873,000
Assets Leased to Others [Member]
Cost, Depreciation	499,000	735,000
Property, Plant and Equipment, Net, Ending Balance	$ 1,399,000	$ 1,811,000

Note 5 - Property and Equipme_4

Note 5 - Property and Equipment, Net - Property and Equipment (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Property and Equipment		$ 5,227,000	$ 8,468,000
Less: Accumulated depreciation and amortization		(3,155,000)	(5,564,000)
Property, Plant and Equipment, Net, Ending Balance	$ 1,873,000	2,078,000	2,950,000
Software Development [Member]
Property and Equipment		124,000	248,000
Computer Equipment [Member]
Property and Equipment		197,000	717,000
Machinery and Equipment [Member]
Property and Equipment		1,784,000	3,351,000
Furniture and Fixtures [Member]
Property and Equipment		78,000	517,000
Leasehold Improvements [Member]
Property and Equipment		326,000	638,000
Assets Leased to Others [Member]
Property and Equipment		2,718,000	2,997,000
Property, Plant and Equipment, Net, Ending Balance		1,399,000	1,811,000
Construction in Progress [Member]
Property and Equipment		$ 6,000	$ 46,000

Note 6 - Accrued Expenses and_3

Note 6 - Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017
Accrued litigation settlement			$ 1,760
Accrued interest payable			364
Accrued sales tax		435
Accrued professional fees		41	288
Accrued travel expenses		74	90
Accrued product warranty costs		272	390
Accrued clinical trial costs		111	57
Accrued restructuring charge		98	98
Other accrued liabilities		418	550
	$ 681	$ 1,449	$ 3,597

Note 7 - Borrowings (Details Te

Note 7 - Borrowings (Details Textual) - USD ($)	Nov. 01, 2018	Feb. 14, 2018	Sep. 22, 2015	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Jan. 24, 2018	Jan. 01, 2018	Mar. 29, 2017	Oct. 28, 2016	Jun. 15, 2016
Line of Credit Facility, Maximum Borrowing Capacity			$ 50,000,000
Debt Instrument, Covenant, Compliance Target Minimum Revenue Second Year			$ 23,000,000										$ 18,000,000
Debt Conversion, Original Debt, Amount							$ 38,000,000	$ 42,794,000
Debt Instrument, Redemption Initial Prepayment Premium Percentage			5.00%
Debt Instrument, Redemption Annual Decline in Prepayment Premium Percentage			1.00%
Debt Instrument, Redemption Prepayment Premium Percentage after Fifth Year			0.00%
Debt Instrument, Financing Fee Percentage			1.50%
Debt Instrument, Final Facility Fee Percentage		15.00%	7.00%
Debt Instrument, Covenant Compliance Cash and Certain Cash Equivalents Minimum		$ 3,500,000	$ 5,000,000							$ 50,000,000	$ 2,500,000
Debt Instrument, Covenant Compliance Target Minimum Revenue First Year			7,000,000
Debt Instrument, Covenant Compliance Target Minimum Revenue Third Year			40,000,000
Debt Instrument, Covenant Compliance Target Minimum Revenue Fourth Year			50,000,000
Debt Instrument, Covenant Compliance Target Minimum Revenue Fifth Year			60,000,000
Debt Instrument, Covenant Compliance Target Minimum Revenue after Year Five			$ 70,000,000
Debt Instrument, Covenant Compliance Prepayment Multiplier for Revenue Shortfall			2
Debt Instrument, Covenant Compliance Target Minimum Revenue Sixth Year		15,000,000
Debt Instrument, Covenant Compliance Target Minimum Revenue Seventh Year		20,000,000
Debt Instrument, Covenant Compliance Target Minimum Revenue Eighth Year		25,000,000
Share Price				$ 0.83		$ 0.83		$ 3
Common Stock [Member]
Stock Issued During Period, Shares, New Issues	728,500				216,618	3,813,559			23,452
Securities Purchase Agreement with CRG [Member] | Common Stock [Member]
Stock Purchase Agreement, Maximum Amount			$ 5,000,000
Stock Issued During Period, Shares, New Issues			870
Shares Issued, Price Per Share			$ 5,596.40
Stock Purchase Agreement Trading Days for Average Price Calculation			10 days
Share Price			$ 5,588
Shares Issued Premium per Share			$ 8.40
CRG [Member] | Loan Agreement [Member]
Long-term Debt, Revenue Milestone, Additional Amount Allowed to Borrow												$ 10,000,000
CRG [Member] | Loan Agreement [Member] | Series A Preferred Stock Purchase Agreement with CRG [Member]
Debt Conversion, Original Debt, Amount		38,000,000
Debt Conversion, Fees and Prepayment Premium Amount		$ 3,800,000
Interest Expense, Debt, Total								$ 3,800,000
Debt Instrument, Interest Rate, Stated Percentage			12.50%
Debt Instrument, Cash Payment of Interest Minimum Percentage			8.50%
Debt Instrument, Maximum Percentage of Interest Convertible into Additional Loans			4.00%
Debt Instrument Period for Interest and Principal Payments			2 years
CRG [Member] | Loan Agreement [Member]
Debt Instrument, Face Amount								2,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net, Total			$ 1,300,000	$ 630,000		$ 630,000		757,000	$ 716,000					$ 154,000
Amortization of Debt Discount (Premium)				$ 42,000	$ 30,000	$ 127,000	$ 84,000	$ 117,000	$ 203,000
CRG [Member] | Loan Agreement [Member] | First Tranche, Borrowed on September 22, 2015 [Member]
Debt Instrument, Face Amount			30,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net, Total			876,000
Debt Instrument, Financing Fee			450,000
Debt Instrument, Other Costs Allocated to Debt Discount			541,000
Debt Instrument, Common Stock Premium Offset Against Debt Discount			$ 115,000
CRG [Member] | Loan Agreement [Member] | Second Tranche, Borrowed on June 15, 2016 [Member]
Debt Instrument, Face Amount														10,000,000
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net, Total														275,000
Debt Instrument, Financing Fee														150,000
Debt Instrument, Other Costs Allocated to Debt Discount														$ 125,000

Note 7 - Borrowings - Schedule

Note 7 - Borrowings - Schedule of Debt (Details) - USD ($)	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Jun. 15, 2016	Sep. 22, 2015
2019
2020
2021
2022
Borrowings, as of December 31, 2018	$ 8,578,000	7,486,000	$ 44,744,000
CRG [Member] | Loan Agreement [Member]
2020	799,000
2021	3,403,000
2022	5,522,000
2023 and after		2,000,000
		2,000,000
Less: Amount of PIK additions and final facility fee to be accreted subsequent to September 30, 2019	(4,497,000)	6,243,000
	13,705,000	8,243,000
Less: Amount representing debt financing costs	(630,000)	(757,000)	$ (716,000)	$ (154,000)	$ (1,300,000)
Borrowings, as of December 31, 2018	$ 8,578,000	$ 7,486,000

Note 8 - Commitments and Cont_2

Note 8 - Commitments and Contingencies (Details Textual)	Dec. 01, 2017USD ($)	May 25, 2017	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2019USD ($)
Operating Leases, Rent Expense, Net, Total			$ 1,015,000	$ 1,833,000
Operating Leases, Future Minimum Payments Due, Total			899,000
Class Action Lawsuits Related to IPO [Member] | Pending Litigation [Member]
Loss Contingency, New Claims Filed, Number		3
Loss Contingency Accrual, Payments			1,760,000
Class Action Lawsuits Related to IPO [Member] | Settled Litigation [Member]
Litigation Settlement, Amount Awarded to Other Party from All Defendants			$ 5,000,000
Facility Lease [Member]
Lessee, Operating Lease, Renewal Term			3 years
Incentive from Lessor			$ 369,000		$ 369,000
Facility Sublease [Member]
Operating Leases Sublease Expiration Prior to Base Lease	15 days
Operating Leases, Monthly Minimum Sublease Rental Payments Receivable Base	$ 79,950
Operating Leases, Monthly Minimum Sublease Rental Payments Receivable Final	$ 82,410

Note 9 - Restructuring Charge_2

Note 9 - Restructuring Charges and Expenses (Details Textual)	1 Months Ended			12 Months Ended
	Oct. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Apr. 30, 2017USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Restructuring Charges, Total					$ 1,285,000
Organizational Realignment [Member]
Restructuring and Related Cost, Number of Positions Eliminated, Period Percent			33.00%
Restructuring and Related Cost, Number of Positions Eliminated				44
Organizational Realignment [Member] | Employee Severance [Member]
Restructuring Charges, Total			$ 519,000
Cost Reduction Plan [Member]
Restructuring and Related Cost, Number of Positions Eliminated		24
Number of Facilities Subleased and Ceased to Use	1
Cost Reduction Plan [Member] | Employee Severance [Member]
Restructuring Charges, Total		$ 416,000
Cost Reduction Plan [Member] | Facility Closing [Member]
Restructuring Charges, Total	$ 388,000
Cost Reduction Plan [Member] | Facility Closing [Member] | Accrued Expenses and Other Current Liabilities [Member]
Restructuring Reserve, Current					$ 98,000

Note 10 - Stockholders' Equit_3

Note 10 - Stockholders' Equity (Deficit) (Details Textual) - USD ($)	Aug. 01, 2019	Jun. 19, 2019	Nov. 01, 2018	Jul. 16, 2018	Jul. 13, 2018	Jul. 12, 2018	Feb. 16, 2018	Feb. 14, 2018	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Aug. 28, 2019	Aug. 22, 2018	Jan. 31, 2015
Preferred Stock, Shares Authorized									5,000,000			5,000,000		5,000,000	5,000,000
Preferred Stock, Par or Stated Value Per Share							$ 0.001		$ 0.001			$ 0.001		$ 0.001	$ 0.001
Preferred Stock, Shares Issued, Total									44,923			44,923		45,671	0
Debt Conversion, Original Debt, Amount													$ 38,000,000	$ 42,794,000
Preferred Stock, Shares Outstanding, Ending Balance									44,923			44,923		45,671	0
Proceeds from Issuance or Sale of Equity, Net	$ 3,800,000		$ 10,200,000		$ 3	$ 3,000,000	$ 15,500,000					$ 8,000,000
Preferred Stock Deemed Dividend Arising from Beneficial Conversion Feature													5,216,000	$ 5,216,000
Common Stock, Shares Authorized									100,000,000			100,000,000		100,000,000	100,000,000
Common Stock, Par or Stated Value Per Share									$ 0.001			$ 0.001		$ 0.001	$ 0.001
Common Stock, Shares, Issued, Total									10,342,179			10,342,179		3,492,200	83,360
Class of Warrant or Right, Outstanding									2,753,999			2,753,999		4,757,539	5,380
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							1,797,900
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period												4 years		4 years
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period												10 years		10 years
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period												0		0
Share-based Payment Arrangement, Expense, Tax Benefit									$ 0	$ 0		$ 0	0	$ 0	$ 0
Share Price									$ 0.83			$ 0.83		$ 3
Common Stock, Shares, Outstanding, Ending Balance									10,342,179			10,342,179		3,492,200	83,360
Share-based Payment Arrangement, Option [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total									$ 142,000			$ 142,000		$ 430,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition												1 year		1 year 109 days
Restricted Stock Units (RSUs) [Member]
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total									$ 3,600,000			$ 3,600,000		$ 4,300,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition												2 years		2 years 182 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number, Ending Balance									941,568			941,568		294,066	509
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Fair Value									$ 782,000			$ 782,000		$ 900,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value												$ 110,000	$ 1,000	$ 1,500	$ 97,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value												$ 1.24	$ 15.80	$ 15	$ 1,144.10
Minimum [Member] | Common Stock Options [ member]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent												100.00%		100.00%
Minimum [Member] | Common Stock Options [ member] | Stockholder with More than 10% Voting Power [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent											110.00%			110.00%
Minimum [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period												3 years		3 years
Maximum [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period												4 years		4 years
The 2015 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized																		3,300
Share-based Compensation Arrangement by Share-based Payment Award, Additional Shares Reserved for Issuance, Annual																		4,225
Share-based Compensation Arrangement by Share-based Payment Award, Additional Shares Reserved for Issuance, Percentage on Shares Outstanding																		5.00%
Share-based Compensation Arrangement by Share-based Payment Award, Other Share Increase (Decrease)														4,167
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized		800,000												300,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant									68,954			68,954		12,668
Officer and Director Share Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized																40,000	20,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant									37,056			37,056
Stock Issued During Period, Shares, Employee Stock Purchase Plans												18,543		4,401
Common Stock Warrants, Issued with Series E Convertible Preferred Stock [Member]
Class of Warrant or Right, Securities Called as Percentage of Convertible Preferred Stock Shares									50.00%			50.00%		50.00%
Class of Warrant or Right, Outstanding														5,380
Class of Warrant or Right, Exercise Price of Warrants or Rights											$ 5,040			$ 5,040
Class of Warrant or Right, Number of Securities Called by Warrants or Rights											5,380
Common Stock Warrants, Issued with Series B Preferred Stock [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							1,797,900		1,768,850			1,768,850		1,768,850
Stock Issued During Period, Shares, Warrants Exercised														290,500
Common Stock Warrants, Issued with Series B Preferred Stock, Warrant One [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights							$ 4
Class of Warrant or Right, Number of Warrants Issued for Each Share of Preferred Stock							1
Class of Warrant or Right, Contingent Expiration Period Following Initial Exercise Date							7 years
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right							50
Common Stock Warrants, Issued with Series B Preferred Stock, Warrant Two [Member]
Class of Warrant or Right, Number of Warrants Issued for Each Share of Preferred Stock							1
Class of Warrant or Right, Contingent Expiration Period Following Initial Exercise Date							7 years
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right							50
Class of Warrant or Right, Expiration Period Following FDA Clearance							60 days
Common Stock Warrants [Member] | Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]
Stock Issued During Period, Shares, New Issues				216,618
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 15.80	$ 15.80	$ 15.80
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				108,309	108,309	108,309								108,309
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right				1		1
Common Stock Warrants [Member] | November Public Offering [Member]
Class of Warrant or Right, Outstanding														28,750,000
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 4
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			2,875,000						876,840			876,840
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right			1
Preferred Stock Warrants [Member] | November Public Offering [Member]
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right			250
Common Stock [Member]
Stock Issued During Period, Shares, New Issues			728,500							216,618		3,813,559			23,452
Stock Issued During Period, Shares, Warrants Exercised												1,998,079		29,050
Stock Issued During Period, Shares, Employee Stock Purchase Plans									10,947	209		18,735	209	4,401
Common Stock [Member] | Placement Agency Sale - Prospectus Supplement of July 12, 2018 [Member]
Stock Issued During Period, Shares, New Issues					216,618	216,618							216,618	216,618
Common Stock [Member] | November Public Offering [Member]
Stock Issued During Period, Shares, New Issues			728,500											728,500
Conversion of Series B Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted												1,523
Conversion of Stock, Shares Issued												380,750
Conversion of Series B Preferred Stock into Common Stock [Member] | Common Stock [Member]
Conversion of Stock, Shares Issued														813,900
Conversion of Series C Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted												2,170
Conversion of Stock, Shares Issued												542,500
Conversion of Series C Preferred Stock into Common Stock [Member] | Common Stock [Member]
Conversion of Stock, Shares Issued														1,604,000
Series A Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance									44,745			44,745		41,800
Dividends Payable														$ 2,900,000
Stock Issued During Period, Shares, New Issues							41,800
Series B Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share							$ 0.001
Preferred Stock, Shares Outstanding, Ending Balance									178			178		1,701
Stock Issued During Period, Shares, New Issues							17,979
Preferred Stock Deemed Dividend Arising from Beneficial Conversion Feature							$ 5,200,000
Series B Preferred Stock [Member] | Conversion of Series B Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted														16,278
Series C Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share			$ 0.001
Preferred Stock, Shares Outstanding, Ending Balance														2,170
Stock Issued During Period, Shares, New Issues			8,586
Proceeds from Issuance or Sale of Equity, Net			$ 10,200,000
Series C Preferred Stock [Member] | November Public Offering [Member]
Stock Issued During Period, Shares, New Issues			8,586
Proceeds from Issuance or Sale of Equity, Net			$ 10,200,000
Series C Preferred Stock [Member] | Conversion of Series C Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted														6,416
Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member] | Series A Preferred Stock [Member]
Convertible Preferred Stock, Shares of Common Stock Issuable on Conversion							2,090,000	2,090,000
Preferred Stock, Dividend Rate, Percentage								8.00%
CRG [Member] | Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member]
Debt Conversion, Original Debt, Amount							$ 38,000,000	$ 38,000,000
Debt Conversion, Fees and Prepayment Premium Amount								3,800,000
Debt Conversion, Converted Instrument, Amount							$ 41,800,000	$ 41,800,000

Note 10 - Stockholders' Equit_4

Note 10 - Stockholders' Equity (Deficit) - Assumptions Used to Estimate Fair Value (Details)	Dec. 31, 2018	Feb. 28, 2018
Measurement Input, Expected Term [Member]
Measurement input	7	7
Measurement Input, Price Volatility [Member]
Measurement input	0.55	0.55
Measurement Input, Risk Free Interest Rate [Member]
Measurement input	0.02	0.02
Measurement Input, Expected Dividend Rate [Member]
Measurement input

Note 10 - Stockholders' Equit_5

Note 10 - Stockholders' Equity (Deficit) - Stock Option Activity (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Options (in shares)	7,954,000	7,664,000
Options, weighted average exercise price (in dollars per share)	$ 1,707.30	$ 2,917.30
Options granted (in shares)		3,100,000
Options granted, weighted average exercise price (in dollars per share)		$ 16.70
Options exercised (in shares)	0	0
Options exercised, weighted average exercise price (in dollars per share)
Options expired (in shares)	(433,000)	(2,551,000)
Options expired, weighted average exercise price (in dollars per share)	$ 3,015.01	$ 2,725.80
Options forfeited (in shares)	(105,000)	(259,000)
Options forfeited, weighted average exercise price (in dollars per share)	$ 1,929.52	$ 3,493.70
Options (in shares)	7,416,000	7,954,000
Options, weighted average exercise price (in dollars per share)	$ 1,316.32	$ 1,707.30
Options, weighted average remaining contractual life (Year)	7 years 18 days	7 years 251 days
Exercisable (in shares)	(7,181,000)	(4,330,000)
Exercisable, weighted average exercise price (in dollars per share)	$ 1,300.40	$ 2,469.70
Exercisable, weighted average remaining contractual life (Year)	7 years 18 days	6 years 149 days
Vested and expected to vest (in shares)	(7,416,000)	(7,954,000)
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 1,316.32	$ 1,707.30
Vested and expected to vest, weighted average remaining contractual life (Year)	7 years 18 days	7 years 251 days

Note 10 - Stockholders' Equit_6

Note 10 - Stockholders' Equity (Deficit) - Options Outstanding and Vested (Details)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Exercise Price (in dollars per share)
Options Outstanding (in shares) | shares	7,954
Weighted Average Remaining Contractual Life (Year)	7 years 251 days
Weighted Average Exercise Price (in dollars per share)	$ 1,707.57
Number Exercisable (in shares) | shares	4,330
Weighted Average Exercise Price, options vested (in dollars per share)	$ 2,470.67
Exercise Price Range 1 [Member]
Exercise Price (in dollars per share)	$ 16.70
Options Outstanding (in shares) | shares	3,100
Weighted Average Remaining Contractual Life (Year)	9 years 160 days
Weighted Average Exercise Price (in dollars per share)	$ 16.70
Number Exercisable (in shares) | shares
Weighted Average Exercise Price, options vested (in dollars per share)	$ 16.70
Exercise Price Range 2 [Member]
Exercise Price (in dollars per share)	$ 204
Options Outstanding (in shares) | shares	5
Weighted Average Remaining Contractual Life (Year)	8 years 204 days
Weighted Average Exercise Price (in dollars per share)	$ 204
Number Exercisable (in shares) | shares	2
Weighted Average Exercise Price, options vested (in dollars per share)	$ 204
Exercise Price Range 3 [Member]
Exercise Price (in dollars per share)	$ 820
Options Outstanding (in shares) | shares	798
Weighted Average Remaining Contractual Life (Year)	8 years 76 days
Weighted Average Exercise Price (in dollars per share)	$ 820
Number Exercisable (in shares) | shares	679
Weighted Average Exercise Price, options vested (in dollars per share)	$ 820
Exercise Price Range 4 [Member]
Exercise Price (in dollars per share)	$ 1,052
Options Outstanding (in shares) | shares	47
Weighted Average Remaining Contractual Life (Year)	8 years 65 days
Weighted Average Exercise Price (in dollars per share)	$ 1,052
Number Exercisable (in shares) | shares	25
Weighted Average Exercise Price, options vested (in dollars per share)	$ 1,052
Exercise Price Range 5 [Member]
Exercise Price (in dollars per share)	$ 1,420
Options Outstanding (in shares) | shares	69
Weighted Average Remaining Contractual Life (Year)	7 years 306 days
Weighted Average Exercise Price (in dollars per share)	$ 1,420
Number Exercisable (in shares) | shares	69
Weighted Average Exercise Price, options vested (in dollars per share)	$ 1,420
Exercise Price Range 6 [Member]
Exercise Price (in dollars per share)	$ 1,472
Options Outstanding (in shares) | shares	11
Weighted Average Remaining Contractual Life (Year)	7 years 292 days
Weighted Average Exercise Price (in dollars per share)	$ 1,472
Number Exercisable (in shares) | shares	6
Weighted Average Exercise Price, options vested (in dollars per share)	$ 1,472
Exercise Price Range 7 [Member]
Exercise Price (in dollars per share)	$ 1,620
Options Outstanding (in shares) | shares	7
Weighted Average Remaining Contractual Life (Year)	160 days
Weighted Average Exercise Price (in dollars per share)	$ 1,620
Number Exercisable (in shares) | shares	7
Weighted Average Exercise Price, options vested (in dollars per share)	$ 1,620
Exercise Price Range 8 [Member]
Exercise Price (in dollars per share)	$ 1,800
Options Outstanding (in shares) | shares	2,704
Weighted Average Remaining Contractual Life (Year)	5 years 361 days
Weighted Average Exercise Price (in dollars per share)	$ 1,800
Number Exercisable (in shares) | shares	2,704
Weighted Average Exercise Price, options vested (in dollars per share)	$ 1,800
Exercise Price Range 9 [Member]
Exercise Price (in dollars per share)	$ 1,980
Options Outstanding (in shares) | shares	25
Weighted Average Remaining Contractual Life (Year)	1 year 120 days
Weighted Average Exercise Price (in dollars per share)	$ 1,980
Number Exercisable (in shares) | shares	25
Weighted Average Exercise Price, options vested (in dollars per share)	$ 1,980
Exercise Price Range 10 [Member]
Exercise Price (in dollars per share)	$ 4,364
Options Outstanding (in shares) | shares	10
Weighted Average Remaining Contractual Life (Year)	6 years 65 days
Weighted Average Exercise Price (in dollars per share)	$ 4,364
Number Exercisable (in shares) | shares	9
Weighted Average Exercise Price, options vested (in dollars per share)	$ 4,364
Exercise Price Range 11 [Member]
Exercise Price (in dollars per share)	$ 4,404
Options Outstanding (in shares) | shares	23
Weighted Average Remaining Contractual Life (Year)	7 years 160 days
Weighted Average Exercise Price (in dollars per share)	$ 4,404
Number Exercisable (in shares) | shares	23
Weighted Average Exercise Price, options vested (in dollars per share)	$ 4,404
Exercise Price Range 12 [Member]
Exercise Price (in dollars per share)	$ 4,952
Options Outstanding (in shares) | shares	18
Weighted Average Remaining Contractual Life (Year)	7 years 120 days
Weighted Average Exercise Price (in dollars per share)	$ 4,952
Number Exercisable (in shares) | shares	12
Weighted Average Exercise Price, options vested (in dollars per share)	$ 4,952
Exercise Price Range 13 [Member]
Exercise Price (in dollars per share)	$ 5,040
Options Outstanding (in shares) | shares	104
Weighted Average Remaining Contractual Life (Year)	2 years 208 days
Weighted Average Exercise Price (in dollars per share)	$ 5,040
Number Exercisable (in shares) | shares	104
Weighted Average Exercise Price, options vested (in dollars per share)	$ 5,040
Exercise Price Range 14 [Member]
Exercise Price (in dollars per share)	$ 5,184
Options Outstanding (in shares) | shares	150
Weighted Average Remaining Contractual Life (Year)	7 years 69 days
Weighted Average Exercise Price (in dollars per share)	$ 5,184
Number Exercisable (in shares) | shares	103
Weighted Average Exercise Price, options vested (in dollars per share)	$ 5,184
Exercise Price Range 15 [Member]
Exercise Price (in dollars per share)	$ 5,196
Options Outstanding (in shares) | shares	301
Weighted Average Remaining Contractual Life (Year)	7 years 62 days
Weighted Average Exercise Price (in dollars per share)	$ 5,196
Number Exercisable (in shares) | shares	236
Weighted Average Exercise Price, options vested (in dollars per share)	$ 5,196
Exercise Price Range 16 [Member]
Exercise Price (in dollars per share)	$ 5,940
Options Outstanding (in shares) | shares	11
Weighted Average Remaining Contractual Life (Year)	2 years 270 days
Weighted Average Exercise Price (in dollars per share)	$ 5,940
Number Exercisable (in shares) | shares	11
Weighted Average Exercise Price, options vested (in dollars per share)	$ 5,940
Exercise Price Range 17 [Member]
Exercise Price (in dollars per share)	$ 6,084
Options Outstanding (in shares) | shares	11
Weighted Average Remaining Contractual Life (Year)	6 years 211 days
Weighted Average Exercise Price (in dollars per share)	$ 6,084
Number Exercisable (in shares) | shares	9
Weighted Average Exercise Price, options vested (in dollars per share)	$ 6,084
Exercise Price Range 18 [Member]
Exercise Price (in dollars per share)	$ 7,844
Options Outstanding (in shares) | shares	118
Weighted Average Remaining Contractual Life (Year)	6 years 324 days
Weighted Average Exercise Price (in dollars per share)	$ 7,844
Number Exercisable (in shares) | shares	92
Weighted Average Exercise Price, options vested (in dollars per share)	$ 7,844
Exercise Price Range 19 [Member]
Exercise Price (in dollars per share)	$ 8,100
Options Outstanding (in shares) | shares	379
Weighted Average Remaining Contractual Life (Year)	7 years 80 days
Weighted Average Exercise Price (in dollars per share)	$ 8,100
Number Exercisable (in shares) | shares	186
Weighted Average Exercise Price, options vested (in dollars per share)	$ 8,100
Exercise Price Range 20 [Member]
Exercise Price (in dollars per share)	$ 8,820
Options Outstanding (in shares) | shares	63
Weighted Average Remaining Contractual Life (Year)	8 years 73 days
Weighted Average Exercise Price (in dollars per share)	$ 8,820
Number Exercisable (in shares) | shares	28
Weighted Average Exercise Price, options vested (in dollars per share)	$ 8,820

Note 10 - Stockholders' Equit_7

Note 10 - Stockholders' Equity (Deficit) - Restricted Stock Units Award Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Awards outstanding, Shares (in shares)	294,066	509	509
Awards outstanding, Weighted grant date fair value (in dollars per share)	$ 17.34	$ 2,377.80	$ 2,377.80
Awards outstanding, Weighted average remaining contractual term (Year)	2 years		3 years 36 days	2 years 317 days
Awarded, Shares (in shares)	764,151		297,753
Awarded, Weighted grant date fair value (in dollars per share)	$ 1.24	$ 15.80	$ 15	$ 1,144.10
Released, Shares (in shares)	(96,444)		(128)
Released, Weighted grant date fair value (in dollars per share)	$ 17.86		$ 2,739.70
Forfeited, Shares (in shares)	(20,205)		(4,068)
Forfeited, Weighted grant date fair value (in dollars per share)	$ 20.46		$ 59.70
Awards outstanding, Shares (in shares)	941,568		294,066	509
Awards outstanding, Weighted grant date fair value (in dollars per share)	$ 4.15		$ 17.34	$ 2,377.80

Note 11 - Stock-based Compens_3

Note 11 - Stock-based Compensation - Noncash Stock-based Compensation Expense Related to Stock Options, ESPP, and RSUs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017
Allocated Share-based Compensation Expense	$ 523	$ 768	$ 1,532	$ 2,028	$ 3,080	$ 4,966
Cost of Sales [Member]
Allocated Share-based Compensation Expense	40	20	128	56	97	269
Research and Development Expense [Member]
Allocated Share-based Compensation Expense	122	137	339	353	547	1,766
Selling, General and Administrative Expenses [Member]
Allocated Share-based Compensation Expense	$ 361	$ 611	$ 1,065	$ 1,619	$ 2,436	$ 2,931

Note 12 - Income Taxes (Details

Note 12 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Tax Expense (Benefit), Total
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	7,600	(20,900)
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	0	0
State and Local Jurisdiction [Member]
Income Tax Expense (Benefit), Total	0	0
Operating Loss Carryforwards, Total		$ 199,300
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	3,100
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	282,700
Operating Loss Carryforwards, Not Subject to Expiration	25,200
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 2,800

Note 12 - Income Taxes - Effect

Note 12 - Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Tax at federal statutory rate	$ (5,787)	$ (16,565)
Federal Tax rate remeasurement		35,953
State taxes, net of federal benefit	(1,023)	993
Permanent differences	228	525
Change in valuation allowance	6,582	(22,554)
Research credits		(229)
Other		1,877
Provision for taxes

Note 12 - Income Taxes - Deferr

Note 12 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Federal, state and foreign net operating losses	$ 70,286	$ 62,057
Research and other credits	3,655	3,632
Fixed assets	(176)
Fixed assets		604
Accruals and other	4,317	4,208
Total net deferred tax assets	78,082	70,501
Less: Valuation allowance	(78,082)	(70,501)
Net deferred tax assets

Note 12 - Income Taxes - Reconc

Note 12 - Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Balance	$ 1,747	$ 1,536
Increase based on the tax positions in the current year	29	211
Decrease for tax positions of prior year	(16)
Balance	$ 1,760	$ 1,747

Note 13 - Related-party Trans_2

Note 13 - Related-party Transactions (Details Textual) - Consensys Imaging Services [Member] - Field Engineers Services [Member] - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction, Expenses from Transactions with Related Party	$ 84,000	$ 188,000
Accounts Payable, Related Parties	$ 12,000	$ 6,000

Note 14 - 401(k) Plan (Details

Note 14 - 401(k) Plan (Details Textual) - Pension Plan [Member] - The 401(k) Plan [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	90.00%
Defined Contribution Plan, Employers Contribution Vesting Period	4 years
Defined Contribution Plan, Cost	$ 0

Note 15 - Reverse Stock Split (

Note 15 - Reverse Stock Split (Details Textual)	Jun. 19, 2019	Jan. 30, 2018
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	10	40