Avinger (AVGR) 10-K 15 Mar 23 2022 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Mar. 10, 2023	Jun. 30, 2022
Document Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Document Transition Report	false
Entity File Number	001-36817
Entity Registrant Name	AVINGER, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-8873453
Entity Address, Address Line One	400 Chesapeake Drive
Entity Address, City or Town	Redwood City
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94063
City Area Code	650
Local Phone Number	241-7900
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	AVGR
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 8.8
Entity Common Stock, Shares Outstanding (in shares)		8,614,508
Auditor Name	Moss Adams LLP
Auditor Location	San Francisco, CA
Auditor Firm ID	659
Entity Central Index Key	0001506928
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false

Balance Sheets

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 14,603	$ 19,497
Accounts receivable, net of allowance for doubtful accounts of $73 and $6 at December 31, 2022 and 2021, respectively	1,057	1,393
Inventories, net	4,965	4,601
Prepaid expenses and other current assets	362	300
Total current assets	20,987	25,791
Right of use asset	2,194	3,179
Property and equipment, net	702	95
Other assets	312	420
Total assets	24,195	29,485
Current liabilities:
Accounts payable	631	1,394
Accrued compensation	1,401	1,609
Accrued expenses and other current liabilities	657	718
Leasehold liability, current portion	1,092	985
Borrowings, current portion	14,165	0
Total current liabilities	17,946	4,706
Borrowings, long-term portion	0	12,287
Leasehold liability, long-term portion	1,102	2,194
Other long-term liabilities	1,001	575
Total liabilities	20,049	19,762
Commitments and Contingencies
Stockholders’ equity:
Convertible preferred stock issuable in series, par value of $0.001 Shares authorized: 5,000,000 at December 31, 2021 and 2020 Shares issued and outstanding: 60,961 and 56,451 at December 31, 2022 and 2021, respectively; aggregate liquidation preference related to Series A convertible preferred stock of $60,876 and $56,366 at December 31, 2022 and 2021, respectively	$ 0	$ 0
Common Stock, Shares Authorized (in shares)	100,000,000	100,000,000
Common stock, par value of $0.001; Shares authorized: 100,000,000 at December 31, 2021 and 2020; Shares issued and outstanding: 7,832,644 and 4,778,263 at December 31, 2022 and 2021, respectively	$ 8	$ 5
Additional paid-in capital	406,514	394,471
Accumulated deficit	(402,376)	(384,753)
Total stockholders’ equity	4,146	9,723
Total liabilities and stockholders’ equity	$ 24,195	$ 29,485

Balance Sheets (Parentheticals)

Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accounts Receivable, Allowance for Credit Loss, Current	$ 73	$ 6
Preferred Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized (in shares)	5,000,000	5,000,000
Preferred Stock, Shares Issued (in shares)	60,961	56,451
Preferred Stock, Shares Outstanding, Ending Balance (in shares)	60,961	56,451
Preferred Stock, Liquidation Preference, Value	$ 60,876	$ 56,366
Common Stock, Par or Stated Value Per Share (in dollars per share)	$ 0.001	$ 0.001
Common Stock, Shares Authorized (in shares)	100,000,000	100,000,000
Common Stock, Shares, Issued (in shares)	7,832,644	4,778,263
Common Stock, Shares, Outstanding, Ending Balance (in shares)	7,832,644	4,778,263

Statements of Operations and Co

Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Revenues	$ 8,273	$ 10,130
Cost of revenues	5,619	6,706
Gross profit	2,654	3,424
Operating expenses:
Research and development	4,390	5,900
Selling, general and administrative	14,221	15,625
Total operating expenses	18,611	21,525
Loss from operations	(15,957)	(18,101)
Interest expense, net	(1,665)	(1,648)
Other (expense) income, net	(1)	2,337
Net loss and comprehensive loss	(17,623)	(17,412)
Accretion of preferred stock dividends	(4,510)	(4,175)
Deemed dividend arising from beneficial conversion feature of convertible preferred stock	(5,111)	0
Net loss applicable to common stockholders	$ (27,244)	$ (21,587)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (4.36)	$ (4.57)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	6,249	4,722

Statements of Stockholders' Equ

Statements of Stockholders' Equity - USD ($) $ in Thousands	Preferred Stock [Member] January 2022 Public Offering [Member]	Preferred Stock [Member] Series D Preferred Stock [Member]	Preferred Stock [Member]	Common Stock [Member] January 2022 Public Offering [Member]	Common Stock [Member] Series D Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member] January 2022 Public Offering [Member]	Additional Paid-in Capital [Member] Series D Preferred Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member] January 2022 Public Offering [Member]	Retained Earnings [Member] Series D Preferred Stock [Member]	Retained Earnings [Member]	January 2022 Public Offering [Member]	Series D Preferred Stock [Member]	Total
Balance at December 31, 2020 (in shares) at Dec. 31, 2020			52,369			4,246,308
Balance at December 31, 2020 at Dec. 31, 2020						$ 4			$ 380,413			$ (367,341)			$ 13,076
Issuance of common stock in public offerings, net of commissions and issuance costs (in shares)			0			500,000
Issuance of common stock in public offerings, net of commissions and issuance costs						$ 1			13,043			0			13,043
Conversion of Series B preferred stock into common stock (in shares)			(93)			18,600
Issuance of common stock upon vesting of restricted stock units (in shares)			0			13,355
Employee stock-based compensation						$ 0			1,015			0			1,015
Issuance of Series A preferred stock to pay dividends (in shares)			4,175			0
Issuance of Series A preferred stock to pay dividends						$ 0			4,175			0			4,175
Accretion of Series A preferred stock dividends						0			(4,175)			0			(4,175)
Net and comprehensive loss						$ 0			0			(17,412)			(17,412)
Balance at December 31, 2021 (in shares) at Dec. 31, 2021			56,451			4,778,263
Balance at December 31, 2021 at Dec. 31, 2021						$ 5			394,471			(384,753)			9,723
Issuance of common stock in public offerings, net of commissions and issuance costs (in shares)	0	7,600		1,285,603	0
Issuance of common stock in public offerings, net of commissions and issuance costs				$ 1	$ 0		$ 5,195	$ 6,721		$ 0	$ 0		$ 5,196	$ 6,721
Conversion of Series B preferred stock into common stock (in shares)			(7,600)			950,000
Issuance of common stock upon vesting of restricted stock units (in shares)			0			8,590
Employee stock-based compensation						$ 0			127			0			127
Issuance of Series A preferred stock to pay dividends (in shares)			4,510			0
Issuance of Series A preferred stock to pay dividends						$ 0			4,510			0			4,510
Accretion of Series A preferred stock dividends						0			(4,510)			0			(4,510)
Net and comprehensive loss						0			0			(17,623)			(17,623)
Conversion of Series D preferred stock into common stock						$ 1			0			0			1
Exercise of pre-funded warrants for common stock (in shares)			0			784,019
Exercise of pre-funded warrants for common stock						$ 1			0			0			1
Reclassifications and adjustments due to rounding impact from reverse stock split for fractional shares (in shares)			0			26,169
Reclassifications and adjustments due to rounding impact from reverse stock split for fractional shares						$ 0			0			0			0
Issuance of common stock upon vesting of restricted stock units						$ 0			0			0			0
Balance at December 31, 2021 (in shares) at Dec. 31, 2022			60,961			7,832,644
Balance at December 31, 2021 at Dec. 31, 2022						$ 8			$ 406,514			$ (402,376)			$ 4,146

Statements of Cash Flows

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities
Net loss	$ (17,623)	$ (17,412)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	196	687
Amortization of debt issuance costs and debt discount	83	86
Stock-based compensation	127	1,015
Noncash interest expense and other charges	1,795	1,564
Change in right of use asset	93	133
Provision for excess and obsolete inventories	272	125
Gain on extinguishment of debt	0	(2,353)
Other non-cash charges	69	2
Changes in operating assets and liabilities:
Accounts receivable	269	89
Inventories	(1,387)	(849)
Prepaid expenses and other current assets	(62)	50
Other assets	15	(43)
Accounts payable	(764)	679
Accrued compensation	(208)	(94)
Accrued expenses and other current liabilities	(61)	49
Other long-term liabilities	426	575
Net cash used in operating activities	(16,760)	(15,697)
Cash flows from investing activities
Purchase of property and equipment	(51)	(34)
Net cash used in investing activities	(51)	(34)
Cash flows from financing activities
Net cash provided by financing activities	11,917	13,043
Net change in cash and cash equivalents	(4,894)	(2,688)
Cash and cash equivalents, beginning of period	19,497	22,185
Cash and cash equivalents, end of period	14,603	19,497
Noncash investing and financing activities:
Accretion of Series A preferred stock dividends	4,510	4,175
Issuance of Series A preferred stock as dividend payment	4,510	4,175
Transfers between inventory and property and equipment	751	(1)
Purchases of property and equipment in accounts payable	0	21
Common Stock [Member]
Cash flows from financing activities
Proceeds from the issuance of convertible preferred stock, net of commissions and issuance costs	6,721	0
Preferred Stock [Member]
Cash flows from financing activities
Proceeds from the issuance of convertible preferred stock, net of commissions and issuance costs	$ 5,196	$ 13,043

Financial Statements Schedules

Financial Statements Schedules	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	(a)(2) Financial Statement Schedules All other schedules have been omitted because the information required to be set forth therein is not applicable or is shown in the financial statements or notes thereto. Financial statement schedules relating to the allowance for doubtful accounts receivable and for sales returns follows (in thousands): Description Balance at Beginning of Year Charged to costs and expenses Write offs Balance at End of Year Allowance for doubtful accounts receivable: Fiscal year ended 2021 $ 19 $ 2 $ 15 $ 6 Fiscal year ended 2022 $ 6 $ 70 $ 3 $ 73 Balance at Beginning of Year Charged to costs and expenses Write offs Balance at End of Year Allowance for sales returns: Fiscal year ended 2021 $ 20 $ 10 $ 10 $ 20 Fiscal year ended 2022 $ 20 $ — $ 5 $ 15

Note 1 - Organization

Note 1 - Organization	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Nature of Operations [Text Block]	1. Organization Organization, Nature of Business Avinger, Inc. (the “Company”), a Delaware corporation, was incorporated in March 2007. The Company designs, manufactures and sells image-guided, catheter-based systems that are used by physicians to treat patients with peripheral artery disease (“PAD”). Patients with PAD have a build-up of plaque in the arteries that supply blood to areas away from the heart, particularly the pelvis and legs. The Company manufactures and sells a suite of products in the United States (“U.S.”) and in select international markets. The Company has developed its Lumivascular platform, which integrates optical coherence tomography (“OCT”) visualization with interventional catheters and is the industry’s only system that provides real-time intravascular imaging during the treatment portion of PAD procedures. The Company’s Lumivascular platform consists of a capital component, Lightbox consoles, as well as a variety of disposable catheter products. The Company’s current catheter products include Ocelot and Tigereye, which are designed to allow physicians to penetrate a total blockage in an artery, known as a chronic total occlusion (“CTO”). The Company also has image-guided atherectomy products, Pantheris and Pantheris SV, which are designed to allow physicians to precisely remove arterial plaque in PAD patients. The Company is in the process of developing next-generation CTO crossing devices to target coronary CTO markets. The Company is located in Redwood City, California. 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) In the course of its activities, the Company has incurred losses and negative cash flows from operations since its inception. As of December 31, 2022, the Company had an accumulated deficit of $402.4 million. The Company expects to incur losses for the foreseeable future. The Company believes that its cash and cash equivalents of $14.6 million at December 31, 2022 and expected revenues from operations will be sufficient to allow the Company to fund its current operations through the end of the third quarter of 2023. The Company received net proceeds of approximately $4.4 million from the sale of its common stock in August 2022, $0.8 million from the sale of its common stock under an At The Market Offering Agreement during the year ended December 31, 2022, $6.7 million from the January 2022 Series D preferred stock and $13.0 million from the sale of its common stock in February 2021. The Company may seek to raise additional funds in future equity offerings to meet its operational needs and capital requirements for product development, clinical trials and commercialization or other strategic objectives. The Company can provide no assurance that it will be successful in raising funds pursuant to additional equity or debt financings or that such funds will be raised at prices that do not create substantial dilution for its existing stockholders. Given the volatility in the Company’s stock price, any financing that the Company may undertake in the next twelve months could cause substantial dilution to its existing stockholders, and there can be no assurance that the Company will be successful in acquiring additional funding at levels sufficient to fund its various endeavors. These conditions raise substantial doubt about the Company’s ability to continue as a going concern. In addition, the COVID-19 pandemic and macroeconomic environment have in the past and could result in reduced consumer and investor confidence, instability in the credit and financial markets, volatile corporate profits, restrictions on elective medical procedures, and reduced business and consumer spending, which could increase the cost of capital and/or limit the availability of capital to the Company. If the Company is unable to raise additional capital in sufficient amounts or on terms acceptable to it, the Company may have to significantly reduce its operations or delay, scale back or discontinue the development and sale of one or more of its products. The financial statements do not include any adjustments that might result from the outcome of this uncertainty. The Company’s ultimate success will largely depend on its continued development of innovative medical technologies, its ability to successfully commercialize its products and its ability to raise significant additional funding. 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 Partners III L.P. and certain of its affiliated funds (collectively “CRG”), the entire amount of outstanding borrowings at December 31, 2022 and 2021 has been classified as current in these financial statements. CRG has not purported that an Event of Default (as defined in the Loan Agreement) has occurred due to a Material Adverse Change. Currently all of our cash and cash equivalents are held at a single financial institution, Silicon Valley Bank. On March 10, 2023, the Federal Deposit Insurance Corporation announced that Silicon Valley Bank had been closed by the California Department of Financial Protection and Innovation. While we have regained access to our accounts at Silicon Valley Bank and are evaluating our banking relationships, future disruptions of financial institutions where we bank or have credit arrangements, or disruptions of the financial services industry in general, could adversely affect our ability to access our cash and cash equivalents. If we are unable to access our cash and cash equivalents as needed, our financial position and ability to operate our business will be adversely affected. Public Offerings Past Offerings On February 2, 2021, under a shelf registration statement, the Company completed a bought deal offering of 500,000 shares of common stock at an offering price of $28.80 per share. As a result, the Company received aggregate net proceeds of approximately $13.0 million after underwriting discounts, commissions, legal and accounting fees, and other ancillary expenses. January 2022 Offering On January 14, 2022, the Company entered into a securities purchase agreement with several institutional investors pursuant to which the Company agreed to sell and issue, in a registered direct offering (“January 2022 Offering”), an aggregate of 7,600 shares of the Company’s Series D Convertible Preferred Stock, par value of $0.001 per share, at an offering price of $1,000 per share which was convertible into common stock at a conversion price of $8.00 per share. Concurrently, the Company agreed to issue to these investors warrants to purchase up to an aggregate of 807,500 shares of the Company’s common stock (the “Common Warrants”). As a result, the Company received aggregate net proceeds of approximately $6.7 million after underwriting discounts, commissions, legal and accounting fees, and other ancillary expenses. The 807,500 Common Warrants have an exercise price of $9.60 per share and became exercisable beginning July 14, 2022. The Common Warrants will expire five five August 2022 Offering On August 4, 2022, the Company entered into a securities purchase agreement with a single institutional investor for the issuance and sale of 1,484,019 shares of its common stock in a registered direct offering (“RD” or “Registered Direct”) at a purchase price of $1.752 per share, or pre-funded warrants in lieu thereof. In a concurrent private placement, the Company also agreed to issue and sell to the investor 1,369,864 shares of common stock at the same purchase price as in the registered direct offering, or pre-funded warrants in lieu thereof (“Private Placement” and together with the Registered Direct offering the “August 2022 Offering”). As a result, the Company received aggregate net proceeds of approximately $4.4 million after underwriting discounts, commissions, legal and accounting fees, and other ancillary expenses. As a result, in the Registered Direct offering, the Company issued (i) 700,000 shares of common stock, (ii) and pre-funded warrants in lieu of common stock to purchase up to an aggregate of 784,019 shares of common stock (the “RD Pre-Funded Warrants”) and in the Private Placement, the Company issued pre-funded warrants to purchase up to an aggregate of 1,369,864 shares of common stock (the “Private Placement Pre-Funded Warrants” and together with the RD Pre-Funded Warrants the “August 2022 Pre-Funded Warrants”). As of December 31, 2022, Pre-Funded Warrants exercisable for 622,000 shares of the Company’s common stock remained outstanding. In addition, the Company issued to the investor in the August 2022 Offering Series A preferred investment options to purchase up to 2,853,883 additional shares of the Company’s common stock and Series B preferred investment options to purchase up to 2,853,883 additional shares of the Company’s common stock (the “Preferred Investment Options”). The Series A preferred investment options have an exercise price of $1.502 per share, are immediately exercisable, and will expire five two five At The Market Offering Agreement On May 20, 2022, the Company entered into an At The Market Offering Agreement (the “ATM Agreement”) with H.C. Wainwright & Co., LLC (the “Agent”), as sales agent, pursuant to which the Company may offer and sell shares of common stock, par value $0.001 per share (the “Shares”) up to an aggregate offering price of $7,000,000 from time to time, in an at the market public offering. Sales of the Shares are to be made at prevailing market prices at the time of sale, or as otherwise agreed with the Agent. The Agent will receive a commission from the Company of 3.0% of the gross proceeds of any Shares sold under the ATM Agreement. The Shares sold under the ATM Agreement are offered and sold pursuant to the Company’s shelf registration statement on Form S-3, which was initially filed with the Securities and Exchange Commission (the “SEC”) on March 29, 2022 and declared effective on April 7, 2022, and a prospectus supplement and the accompanying prospectus relating to the At The Market Offering filed with the SEC on May 20, 2022. During the year ended December 31, 2022, the Company sold 585,603 shares of common stock pursuant to the ATM Agreement at an average price of $1.67 per share for aggregate proceeds of $1.0 million, of which approximately $29,000 was paid in the form of commissions to the Agent. Other than the ATM Agreement, the Company currently does not have any commitments to obtain additional funds. On August 3, 2022, the Company suspended sales under the ATM Agreement. The Company plans to reactivate the ATM Agreement in March 2023 and may resume sales in the future. However, there can be no assurance that the Company will be successful in acquiring additional funding through these means.

Note 2 - Summary of Significant

Note 2 - Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Basis of Presentation and Significant Accounting Policies [Text Block]	2. Summary of Significant Accounting Policies 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 Securities and Exchange Commission (“SEC”). On March 11, 2022, the Company’s Board of Directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a 1-for-20 reverse stock split of the Company’s issued and outstanding common stock. The reverse stock split became effective on March 14, 2022. The par value of the common stock and preferred stock was not adjusted as a result of the reverse stock split. All common stock, stock options, restricted stock units, and per share amounts in the financial statements have been retroactively adjusted for all periods presented to give effect to the reverse stock split. Additionally, the common stock at par and related additional paid-in capital amounts as of December 31, 2021 in the balance sheet, the common stock at par and related additional paid-in capital amounts in the Statement of Stockholder’s Equity as of December 31, 2021 and 2020, and for the year ended December 31, 2021 have also been retroactively reclassified to give effect to the reverse stock split. 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 stock-based compensation, accruals related to compensation, the valuation of the common stock warrants, 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 readily apparent from other sources. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Fair Value of Financial Instruments The Company has evaluated the estimated fair value of its financial instruments as of December 31, 2022 and 2021. Financial instruments consist of cash and cash equivalents, accounts receivable and payable, and other current liabilities and borrowings. The carrying amounts of cash and cash equivalents, accounts receivable and payable, and other current liabilities approximate their respective fair values because of the short-term nature of those instruments. Based upon the borrowing terms and conditions currently available to the Company, the carrying values of the borrowings approximate their fair value. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of three months or less at the time of purchase to be cash equivalents. Cash equivalents are considered available-for-sale marketable securities and are recorded at fair value, based on quoted market prices. As of December 31, 2022 and 2021, the Company’s cash equivalents are entirely comprised of investments in money market funds. Any related unrealized gains and losses are recorded in other comprehensive income (loss) and included as a separate component of stockholders’ equity. There were no 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 financial institution, Silicon Valley Bank. The counterparties to the agreements relating to the Company’s investments consist of financial institutions of high credit standing. 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, 2022 and 2021. On March 10, 2023, the Federal Deposit Insurance Corporation announced that Silicon Valley Bank had been closed by the California Department of Financial Protection and Innovation. While we have regained access to our accounts at Silicon Valley Bank and are evaluating our banking relationships, future disruptions of financial institutions where we bank or have credit arrangements, or disruptions of the financial services industry in general, could adversely affect our ability to access our cash and cash equivalents. If we are unable to access our cash and cash equivalents as needed, our financial position and ability to operate our business will be adversely affected. The Company’s accounts receivable are due from a variety of healthcare organizations in the United States and select international markets. 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, 2022 and 2021. At December 31, 2022, there was no one one The Company manufactures its commercial products in-house, including the Pantheris and Ocelot family of catheters. Certain of the Company’s product components and sub-assemblies are manufactured by sole suppliers, including internally. 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 be approved or cleared for marketing by governmental authorities or be successfully marketed. There can be no assurance that the Company’s products will achieve widespread adoption in the marketplace, nor can there be any assurance that existing devices or any future devices can be developed or manufactured at an acceptable cost and with appropriate performance characteristics. The Company is also subject to risks common to companies in the medical device industry, including, but not limited to, new technological innovations, dependence upon third-party payors to provide adequate coverage and reimbursement, dependence on key personnel and suppliers, protection of proprietary technology, product liability claims, and compliance with government regulations. Existing or future devices developed by the Company may require approvals or clearances from the FDA or international regulatory agencies. In addition, in order to continue the Company’s operations, compliance with various federal and state laws is required. If the Company were denied or delayed in receiving such approvals or clearances, it may be necessary to adjust operations to align with the Company’s currently approved portfolio. If clearance for the products in the current portfolio were withdrawn by the FDA, this may have a material adverse impact on the Company. Disruption of our supply chain capabilities due to trade restrictions, political instability, severe weather, natural disasters, public health crises, terrorism, product recalls, labor supply or stoppages, the financial or operational instability of key suppliers and carriers, government restrictions or measures, or other reasons could impair our ability to distribute our products. The Company believes COVID-19 and the subsequent burdens on the hospital systems has had and will continue to have an adverse effect on its ability to generate sales due to the fluctuating and unpredictable levels of capacity medical providers have to perform procedures that require the use of its products. The Company is closely monitoring general economic conditions on global supply chain, manufacturing, and logistics operations. As inflationary pressures increase, the Company anticipates that its production and operating costs may similarly increase, including costs and availability of materials and labor. While the Company has sufficient inventory on-hand to meet its current production requirements and customer demand, it has experienced some constraints with respect to the availability of certain materials and extended lead times from certain key suppliers. The Company has also experienced some delays in shipping products to its customers. Any significant delay or interruption in our supply chain could impair the Company’s ability to meet the demands of its customers in the future and could harm its business. We use technology in substantially all aspects of our business operations, and our ability to serve customers most effectively depends on the reliability of our technology systems. Cybersecurity incidents can include computer viruses, computer denial-of-service attacks, worms, and other malicious software programs or other attacks, covert introduction of malware to computers and networks, impersonation of authorized users, and efforts to discover and exploit any design flaws, bugs, security vulnerabilities or security weaknesses, as well as intentional or unintentional acts by employees or other insiders with access privileges, intentional acts of vandalism by third parties and sabotage. In addition, our technology infrastructure and systems are vulnerable to damage or interruption from natural disasters, power loss and telecommunications failures. Any such disruption to our systems, or the technology systems of third parties on which we rely, the failure of these systems to otherwise perform as anticipated, or the theft, destruction, loss, misappropriation, or release of sensitive and/or confidential information or intellectual property, could require us to notify affected individuals, federal or state agencies or media outlets of the incident and could result in business disruption, negative publicity, loss of customers, potential liability, including litigation or other legal actions against us or the imposition of penalties, fines, fees or liabilities, which may not be covered by our insurance policies, and competitive disadvantage, any or all of which would potentially adversely affect our customer service, decrease the volume of our business and result in increased costs and lower profits. Moreover, a cybersecurity breach could require us to devote significant management resources to address the problems associated with the breach and to expend significant additional resources to upgrade further the security measures we employ to protect information against cyber-attacks and other wrongful attempts to access such information, which could result in a disruption of our operations. While we have invested, and continue to invest, in technology security initiatives and other measures to prevent security breaches and cyber incidents, as well as disaster recovery plans, these initiatives and measures may not be entirely effective to insulate us from technology disruption that could result in adverse effects on our results of operations. Accounts Receivable Trade accounts receivable are recorded at the invoiced amount and do not bear interest. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in the Company’s existing accounts receivable. The Company determines the allowance for doubtful accounts based upon an aging of accounts receivable, historical experience, and management judgment. Accounts receivable balances are reviewed individually for collectability. To date, the Company has not experienced significant credit-related losses. Accounts receivable allowance for doubtful accounts provision and recoveries or write-offs are summarized as follows (in thousands): 2022 2021 Beginning balance $ 6 $ 19 Provision 70 2 Recoveries/write-offs (3 ) (15 ) Ending balance $ 73 $ 6 Inventories Inventories are valued at the lower of cost or net realizable value. Cost is determined using the first-in, first-out method for all inventories. The Company’s policy is to write down inventory that has expired or become obsolete, inventory that has a cost basis in excess of its expected net realizable value, and inventory in excess of expected requirements. At each balance sheet date, management evaluates inventories for excess quantities, and obsolescence. This evaluation by management includes analysis of historical sales levels by product, projections of future demand, the risk of technological or competitive obsolescence for products, general market conditions, as well as the feasibility of reworking or using excess or obsolete products or components in the production or assembly of other products that are not obsolete or for which there are not excess quantities in inventory. To the extent that management determines there are excess or obsolete inventory, management adjusts the carrying value to estimated net realizable value. When quantities on hand exceed sales forecasts, a write-down is recorded for such excess inventories along with a corresponding charge to cost of revenues. The estimate of excess quantities is subjective and primarily dependent on the estimates of future demand for a particular product. Specifically, the future demand is derived based on our historical experience, from discussion with users of our products and general market conditions. Changes in assumptions of product demand could have a significant impact on the amount of write-down recorded. Inventory used in clinical trials is expensed at the time of production and recorded as research and development expense if the inventory is contractually being provided at no cost to the clinical site. The cost of inventories are regularly reviewed against estimated market value and record a lower of cost or market reserve for inventories that have a cost in excess of estimated market value, which could have a material impact on the gross margin and inventory balances based on additional write-downs to net realizable value or a benefit from inventories previously written down. 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 generally three five 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 be fully recoverable. If indicators of impairment exist, an impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of the asset and its eventual disposition are less than its carrying amount. Impairment, if any, is measured as the amount by which the carrying amount of the long-lived asset exceeds its fair value. The Company has not recorded any impairment of long-lived assets since inception through December 31, 2022. Revenue Recognition The Company’s revenues are derived from (1) sale of Lightbox consoles, (2) sale of disposables, which consist of catheters and accessories, and (3) sale of customer service contracts and maintenance. The Company sells its products directly to hospitals and medical centers as well as through distributors. The Company accounts for a contract with a customer when there is a legally enforceable contract between the Company and the customer, the rights of the parties are identified, the contract has commercial substance, and collectability of the contract consideration is probable. The Company’s revenues are measured based on consideration specified in the contract with each customer, net of any sales incentives and taxes collected from customers that are remitted to government authorities. For all sales, the Company uses either a signed agreement or a binding purchase order as evidence of an arrangement. The Company’s revenue recognition policies generally result in revenue recognition at the following points: 1. Lightbox console sales: Provided all other criteria for revenue recognition have been met, the Company recognizes revenue for Lightbox console sales directly to end customers when delivery and acceptance occurs, which is defined as receipt by the Company of an executed form that the 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 consists of preventative maintenance, upgrades, and service contracts. Service contracts are recognized ratably over the term of the service period and maintenance contract revenue is recognized when work is completed. To date, service revenue has been insignificant. The Company offers its customers the ability to purchase or lease the Lightbox console. In addition, the Company provides a Lightbox under a limited commercial evaluation program to allow accounts to install and utilize the Lightbox for a limited trial period. When a Lightbox is placed under a lease agreement or under a commercial evaluation program, the Company retains title to the equipment and it remains capitalized on its balance sheet under property and equipment. Depreciation expense on these placed Lightboxes is recorded to cost of revenues on a straight-line basis. The costs to maintain these placed Lightboxes are charged to cost of revenues as incurred. The Company evaluates its lease and commercial evaluation program agreements and accounts for these contracts under the guidance in Accounting Standards Codification (“ASC”) 842, Leases Revenue from Contracts with Customers (Topic 606) 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 reasonably predictable. Accordingly, the Company concluded the embedded lease did not meet the criteria of a sales-type lease and accounts for it as an operating lease. The Company recognizes revenue allocated to the lease as the contingent disposable product purchases are delivered and are included in revenues within the statement of operations and comprehensive loss. For sales through distributors, the Company recognizes revenue when control of the product 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 provide price protection or stock rotation rights to any of its distributors. In addition, its distributor agreements do not allow the distributor to return or exchange products, and the distributor is obligated to pay the Company upon invoice regardless of its ability to resell the product. 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, deployed with sales personnel and evaluation agreements, product warranty costs, product written-off due to excess or obsolescence, and certain direct costs such as shipping costs. Product Warranty Costs The Company typically offers a one 2022 2021 Beginning balance $ 187 $ 193 Warranty provision 22 49 Usage/Release (100 ) (55 ) Ending balance $ 109 $ 187 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, and internal and external costs associated with the Company’s regulatory compliance, 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 parties, including clinical research organizations and other service providers, based upon estimates of the work completed over the life of the individual study in accordance with associated agreements. The Company determines these estimates through discussion with internal personnel and outside service providers as to progress or stage of completion of trials or services pursuant to contracts with clinical research organizations and other service providers and the agreed-upon fee to be paid for such services. Stock-Based Compensation Stock-based compensation for the Company includes amortization related to all stock options, restricted stock units (“RSU”), and restricted stock awards (“RSA”) 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 has not granted any stock options since 2017. The Company measures the fair value of RSUs and RSAs 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. As allowed under ASU No. 2016‑09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting 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, net. During the years ended December 31, 2022 and 2021, the Company recorded $12,000 and $16,000 of foreign currency exchange net losses, respectively. 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, 2022 and 2021, the Company did 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 applicable 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 applicable 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 December 31, 2022 and 2021, there were no Net loss per share attributable to common stockholders was determined as follows (in thousands, except per share data): Year Ended December 31, 2022 2021 Net loss applicable to common stockholders $ (27,244 ) $ (21,587 ) Weighted average common stock outstanding, basic and diluted 6,249 4,722 Net loss per share attributable to common stockholders, basic and diluted $ (4.36 ) $ (4.57 ) 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: Year Ended December 31, 2022 2021 Common stock warrants equivalents 4,009,679 135,429 Common stock options 303 304 Convertible preferred stock 58,080 52,289 Unvested restricted stock units 6,626 17,817 4,074,688 205,839 Comprehensive Loss For the years ended December 31, 2022 and 2021, there was no difference between comprehensive loss and the Company’s net loss. Segment and Geographical Information The Company operates and manages its business as one Recent Accounting Pronouncements Recently adopted accounting standards In May 2021, ASU No. 2021-04, Issuer s Accounting for Certain Modifications of Exchanges of Freestanding Equity-Classified Written Call Options Recent accounting standards not yet adopted In August 2020, the FASB issued ASU No. 2020-06, Debt Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity s Own Equity

Note 3 - Fair Value Measurement

Note 3 - Fair Value Measurements	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Fair Value Disclosures [Text Block]	3. Fair Value Measurements 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-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than quoted prices included within Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. As of December 31, 2022 and 2021, the Company’s cash equivalents were all categorized as Level 1 and consisted of money market funds. As of December 31, 2022 and 2021, there were no no

Note 4 - Inventories

Note 4 - Inventories	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Inventory Disclosure [Text Block]	4. Inventories Inventories consisted of the following (in thousands): December 31, 2022 2021 Raw materials $ 3,374 $ 2,503 Work-in-process 17 1 Finished products 1,574 2,097 Total inventories $ 4,965 $ 4,601

Note 5 - Property and Equipment

Note 5 - Property and Equipment, Net	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Property, Plant and Equipment Disclosure [Text Block]	5. Property and Equipment, Net Property and equipment, net, consisted of the following (in thousands): December 31, 2022 2021 Equipment held by customers and field sales personnel $ 2,566 $ 2,362 Machinery and equipment 1,372 1,391 Computer software 122 122 Computer equipment 200 173 Furniture and fixture 78 78 Leasehold improvements 320 320 Total property and equipment, gross 4,658 4,446 Less: Accumulated depreciation and amortization (3,956 ) (4,351 ) Total property and equipment, net $ 702 $ 95 Depreciation expense for the years ended December 31, 2022 and 2021, was approximately $196,000 and $687,000, respectively. Property and equipment include certain equipment that is leased to customers and located at customer premises. Also, included is equipment held by the Company’s field sales personnel for use in cases with customers. The Company retains ownership of the equipment held for evaluation by customers and has the right to remove the equipment if it is not being utilized according to expectations. Depreciation expense relating to the leased equipment held by customers and those held by the Company’s field sales personnel of $119,000 and $539,000 was recorded in cost of revenues during the years ended December 31, 2022 and 2021, respectively. The net book value of this equipment was $527,000 and $0 at December 31, 2022 and December 31, 2021, respectively.

Note 6 - Accrued Expenses and O

Note 6 - Accrued Expenses and Other Current Liabilities	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block]	6. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): December 31, 2022 2021 Deferred revenue $ 141 $ 123 Accrued travel and entertainment expenses 129 118 Accrued product warranty costs 109 187 Accrued clinical trial costs 106 153 Accrued professional fees 60 — Accrued sales and use tax 40 33 Other accrued liabilities 72 104 Total accrued expenses and other current liabilities $ 657 $ 718

Note 7 - Borrowings

Note 7 - Borrowings	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Debt Disclosure [Text Block]	7. Borrowings CRG On September 22, 2015, the Company entered into a Term Loan Agreement, as amended (the “Loan Agreement”) with CRG under which, subject to certain conditions, the Company had the right to borrow up to $50 million in principal amount from CRG on or before the end of the twenty-fourth (24th) month period commencing on the first Borrowing Date (as defined in the Loan Agreement). The Company borrowed $30 million on September 22, 2015. The Company borrowed an additional $10 million on June 15, 2016 under the Loan Agreement. On February 14, 2018, the Company and CRG further amended the Loan Agreement concurrent with the conversion of $38 million of the principal amount of the senior secured term loan (plus $3.8 million in back-end fees and prepayment premium applicable thereto) into a newly authorized Series A convertible preferred stock (see below). The Company has entered into several amendments to the Loan Agreement (the “Amendments”) with CRG since September 2015, the most recent of which was entered into on August 10, 2022. The Amendments, among other things: (1) extended the interest-only period through December 31, 2023; (2) extended the period during which the Company may elect to pay a portion of interest in payment-in-kind, or PIK, interest payments through December 31, 2023 so long as no Default (as defined in the Loan Agreement) has occurred and is continuing; (3) permitted the Company to make the entire interest payments in PIK interest payments for through December 31, 2023 so long as no Default has occurred and is continuing; (4) extended the Stated Maturity Date (as defined in the Loan Agreement) to December 31, 2025; (5) reduced the minimum liquidity covenant to $3.5 million at all times; (6) eliminated the minimum revenue covenant for 2018, 2019 and 2020; (7) reduced the minimum revenue covenant to $8 million for 2021 and 2022; (8) added minimum revenue covenants of $10 million for 2023, $14.5 million for 2024 and $17 million for 2025; (9) changed the date under the on-going stand-alone representation regarding no “Material Adverse Change” to December 31, 2020; (10) amended the on-going stand-alone representation and stand-alone Event of Default (as defined in the Loan Agreement) regarding Material Adverse Change such that any adverse change in or effect upon the revenue of the Company and its subsidiaries due to the outbreak of COVID-19 will not constitute a Material Adverse Change; and (11) provided CRG with board observer rights. Under the amended Loan Agreement, no cash payments for either principal or interest are required until the first quarter of 2024. The interest will be accrued and included in the debt balance based (to the extent not paid) on principal amounts outstanding at the beginning of the quarter at an interest rate of 12.5%. Beginning in the first quarter of 2024, the Company will be required to make quarterly principal payments (in addition to the interest) of $1.9 million with total principal payments of $7.5 million in 2024 and $7.5 million in 2025. The maturity date of the Loan (as defined in the Loan Agreement) is December 31, 2025. The Company may voluntarily prepay the borrowings in full, with a prepayment premium beginning at 5.0% and declining by 1.0% annually thereafter, with no premium being payable if prepayment occurs after seven and half years of the loan. Each tranche of borrowing required the payment, on the borrowing date, of a financing fee equal to 1.5% of the borrowed loan principal, which is recorded as a discount to the debt. In addition, a facility fee equal to 15.0% of the amounts borrowed plus any PIK is to be payable at the end of the term or when the borrowings are repaid in full. A long-term liability is being accreted using the effective interest method for the facility fee over the term of the Loan Agreement with a corresponding discount to the debt. The borrowings are collateralized by a security interest in substantially all of the Company’s assets. 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 amended Loan Agreement included a covenant that the Company maintain a minimum of $3.5 million of cash and certain cash equivalents, and the Company has to achieve certain minimum revenues. If the Company fails to meet the applicable minimum revenue target in any calendar year, the Loan Agreement provides the Company with a cure right if it prepays a portion of the outstanding principal equal to 2.0 times the revenue shortfall. In addition, the Loan Agreement prohibits the payment of cash dividends on the Company’s capital stock and also places restrictions on mergers, sales of assets, investments, incurrence of liens, incurrence of indebtedness and transactions with affiliates. CRG may accelerate the payment terms of the Loan Agreement upon the occurrence of certain “Events of Default” set forth therein, which include the failure of the Company to make timely payments of amounts due under the Loan Agreement, the failure of the Company to adhere to the covenants set forth in the Loan Agreement, the insolvency of the Company or upon the occurrence of a “Material Adverse Change” thereunder. As of December 31, 2022, the Company was in compliance with all applicable covenants under the Loan Agreement. As of December 31, 2022, principal, final facility fee and PIK payments under the Loan Agreement, as amended, were as follows (in thousands): Year Ending December 31, 2023 $ — 2024 9,045 2025 10,339 Total 19,384 Less: Amount of PIK additions and final facility fee to be incurred subsequent to December 31, 2022 (4,970 ) Less: Amount representing debt issuance costs (249 ) Borrowings, current portion, as of December 31, 2022 $ 14,165 In connection with drawdowns under the Loan Agreement, the Company recorded aggregate debt discounts of $1.3 million as contra-debt. The debt discounts are being amortized as non-cash interest expense using the effective interest method over the term of the Loan Agreement. As of December 31, 2022 and 2021, the balance of the aggregate debt discount was approximately $249,000 and $332,000, respectively. The Company’s interest expense associated with the amortization of debt discount was approximately $83,000 and $86,000 during the years ended December 31, 2022 and 2021, respectively. The Company incurred total interest expense of approximately $1.9 million and $1.6 million during the years ended December 31, 2022 and 2021, respectively. Due to the substantial doubt about the Company’s ability to continue operating as a going concern and the Event of Default (as defined in the Loan Agreement) that could result due to a “Material Adverse Change” under the Loan Agreement, the entire outstanding amount of borrowings under the Loan Agreement and associated aggregate debt discount at December 31, 2022 was classified as current in these financial statements as compared with long-term as of December 31, 2021. CRG has not purported that an Event of Default has resulted due to a Material Adverse Change. Paycheck Protection Program On April 23, 2020, the Company received loan proceeds of $2.3 million (the “PPP Loan”) pursuant to the Paycheck Protection Program under the CARES Act. The PPP Loan, which was in the form of a promissory note, dated April 20, 2020 (the “Promissory Note”), between the Company and Silicon Valley Bank (“SVB”) as the lender, was set to mature on April 20, 2022 and bore interest at a fixed rate of 1% per annum, payable monthly commencing six months from the date of the Loan, with prepayment of the borrowings permitted with no associated penalty or premium. The PPP Loan was administered by the U.S. Small Business Administration (“SBA”). The SBA was given the authority under the PPP to forgive loans if all employees were kept on the payroll for a required period and the loan proceeds were used for payroll, rent and utilities. The Company applied for debt forgiveness in December 2020. On April 17, 2021, the Company was notified by SVB that its PPP Loan had been fully forgiven by the SBA and that there was no remaining balance on the PPP Loan. The Company recorded the forgiveness as other income in April 2021 in the amount of $2.4 million, of which approximately $23,000 was accrued interest. For the year ended December 31, 2021, the Company incurred interest expense of approximately $7,000 related to the PPP Loan.

Note 8 - Leases

Note 8 - Leases	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Lessee, Operating Leases [Text Block]	8. Leases The Company’s operating lease obligations primarily consist of leased office, laboratory, and manufacturing space under a non-cancelable operating lease. In addition to the minimum future lease commitments presented below, the lease requires the Company to pay property taxes, insurance, maintenance, and repair costs. The lease includes a rent holiday concession and escalation clauses for increased rent over the lease term. Rent expense is recognized using the straight-line method over the term of the lease. The lease will expire on November 30, 2024. The Company is obligated to pay approximately $5.8 million in base rent payments through November 2024, beginning on December 1, 2019. The weighted average remaining lease term as of December 31, 2022 is 1.9 years. The operating lease was included on the balance sheet at the present value of the future base payments discounted at a 6.5% discount rate using the rate of interest that the Company would have to pay to borrow on a collateralized basis over a similar term and amount equal to the lease payments in a similar economic environment as the lease does provide an implicit rate. The Company’s operating lease expense, excluding variable maintenance fees and other expenses on a monthly basis, was approximately $105,000. Rent expense for each of the years ended December 31, 2022 and 2021 was approximately $ 1.3 The following table presents the future operating lease payments and leasehold liability included on the balance sheet related to the Company’s operating lease as of December 31, 2022 (in thousands): Year Ending December 31, 2023 $ 1,203 2024 1,138 Total 2,341 Less: Imputed interest (147 ) Leasehold liability as of December 31, 2022 $ 2,194 The following table shows ROU assets and lease liabilities, and the associated financial statement line items (in thousands): December 31, Lease-Related Assets and Liabilities Financial Statement Line Items 2022 2021 Right of use assets: Operating lease Right of use asset $ 2,194 $ 3,179 Total right of use assets $ 2,194 $ 3,179 Lease liabilities: Operating lease Leasehold liability, current portion $ 1,092 $ 985 Leasehold liability, long-term portion 1,102 2,194 Total lease liabilities $ 2,194 $ 3,179

Note 9 - Commitments and Contin

Note 9 - Commitments and Contingencies	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	9. Commitments and Contingencies Purchase Obligations Purchase obligations consist of agreements to purchase goods and services entered into in the ordinary course of business. The Company had non-cancelable commitments to suppliers for purchases totaling approximately $1.1 million as of December 31, 2022. The majority of this amount is related to commitments to purchase inventory components for our various product lines. Indemnification In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and may provide for indemnification of the counterparty. The Company’s exposure under these agreements is unknown because it involves claims that may be made against it in the future, but have not yet been made. To date, the Company has not been subject to any claims or been required to defend any action related to its indemnification obligations. 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 be subject to any proceeding arising out of acts or omissions of such director in such capacity. The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director liability insurance. This insurance allows the transfer of risk associated with the Company’s exposure and may enable it to recover a portion of any future amounts paid. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, it has not recognized any liabilities relating to these obligations for any period presented. Legal Proceedings The Company is not currently involved in any pending legal proceedings that it believes could have a material adverse effect on our financial condition, results of operations or cash flows. From time to time, the Company may be involved in legal proceedings or investigations, which could harm our reputation, business and financial condition and divert the attention of our management from the operation of our business.

Note 10 - Stockholders' Equity

Note 10 - Stockholders' Equity	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Stockholders' Equity Note Disclosure [Text Block]	10. Stockholders Equity Convertible Preferred Stock As of December 31, 2022, the Company’s certificate of incorporation, as amended and restated, authorizes the Company to issue up to 5,000,000 shares of convertible preferred stock with $0.001 par value per share. As of December 31, 2022 and 2021, 60,961 and 56,451 shares of convertible preferred stock, respectively, were issued and outstanding. Series A Convertible Preferred Stock The holders of Series A preferred stock are entitled to receive annual accruing dividends at a rate of 8%, payable in additional shares of Series A preferred stock or cash, at the Company’s option. The shares of Series A preferred stock have a liquidation preference of $1,000 per share, no voting rights and rank senior to all other classes and series of the Company’s equity in terms of repayment and certain other rights. During the years ended December 31, 2022 and 2021, 4,510 and 4,175 additional shares, respectively, were issued to CRG as payment of dividends. As of December 31, 2022 and 2021, 60,876 and 56,366 shares of Series A preferred stock were outstanding, respectively, which are currently convertible into shares of the Company’s common stock at $400 per share. The Series A preferred stock accrued additional dividends of approximately $4.5 million and $4.2 million during the years ended December 31, 2022 and 2021, respectively. Series B Convertible Preferred Stock The Series B preferred stock has a liquidation preference of $0.001 per share, full ratchet price based anti-dilution protection, has no voting rights and is subject to certain ownership limitations. The Series B preferred stock is immediately convertible at the option of the holder, has no stated maturity, and does not pay regularly stated dividends or interest. During the year ended December 31, 2021, 93 of these shares converted into 18,600 shares of common stock. As of December 31, 2022 and 2021, 85 shares of Series B preferred stock remained outstanding, which are currently convertible into shares of the Company’s common stock at $1.502 per share. Series D Convertible Preferred Stock On January 14, 2022, the Company entered into a security purchase agreement with several institutional investors, pursuant to which the Company agreed to sell and issue, in a registered direct offering (“January 2022 offering”), an aggregate of 7,600 shares of the Company’s Series D convertible preferred stock, par value $0.001 per share at an offering price of $1,000 per share. Concurrently, the Company agreed to issue to these investors warrants to purchase up to an aggregate of 807,500 shares of the Company’s common stock (the “Common Warrants”). The shares of Series D Preferred Stock has a stated value of $1,000 per share and are convertible into an aggregate of 950,000 shares of common stock at a conversion price of $8.00 per share. On January 14, 2022, the Company entered into a security purchase agreement with several institutional investors, pursuant to which the Company agreed to sell and issue, in a registered direct offering (“January 2022 Offering”), an aggregate of 7,600 shares of the Company’s Series D convertible preferred stock, par value $0.001 per share at an offering price of $1,000 per share. Concurrently, the Company agreed to issue to these investors warrants to purchase up to an aggregate of 807,500 shares of the Company’s common stock (the “Common Warrants”). The shares of Series D preferred stock had a stated value of $1,000 per share and were convertible into an aggregate of 950,000 shares of common stock at a conversion price of $8.00 per share. During the year ended December 31, 2022, all 7,600 shares of Series D preferred stock were converted into a total of 950,000 shares of common stock. Consequently, there were no At the time of issuance, the Company evaluated the classification of the Series D preferred stock and determined equity classification was appropriate due to no mandatory or contingently redeemable redemption features. The warrants issued to the investors were considered freestanding equity classified instruments. The Company first allocated gross proceeds from the registered direct offering between the preferred stock and the warrants issued to investors using a relative fair value approach, resulting in an initial allocation to each instrument of $4.0 million and $3.6 million, respectively. On the issuance date, the Company estimated the fair value of the Common Warrants issued to investors and warrants issued to the placement agent designees using a Black-Scholes option pricing model using the following assumptions: (i) contractual term of 5.5 years, (ii) expected volatility rate of 136.61%, (iii) risk-free interest rate of 1.51%, (iv) expected dividend rate of 0%, and (v) closing price of the Company’s common stock of the day immediately preceding the registered direct offering. The fair value of preferred stock was estimated based upon equivalent common shares that preferred stock could have been converted into at the closing price of the day immediately preceding the purchase date. The embedded conversion feature was evaluated and bifurcation from the preferred stock equity host was not considered necessary. The issuance of the Series D convertible preferred stock generated a beneficial conversion feature (“BCF”) which arose as the equity security was issued with an embedded conversion option that is beneficial to the investor or in the money at inception because the conversion option has an effective conversion price that is less than the market price of the underlying stock at the commitment date. The Company recorded the BCF as a discount to the preferred stock resulting in the amount of $5.1 million based on the intrinsic value of the beneficial conversion. As the preferred stock was immediately convertible into common stock subject to the consummation of the reverse stock split on March 14, 2022, a deemed dividend related to the discount associated with the beneficial conversion feature was recorded on that date. This one-time, non-cash charge impacted net loss applicable to common stockholders and net loss per share attributable to common stockholders for the year ended December 31, 2022. Common Stock At December 31, 2022, the Company’s certificate of incorporation, as amended and restated, authorizes the Company to issue up to 100,000,000 shares of common stock with $0.001 par value per share, of which 7,832,644 shares were issued and outstanding. Common Stock Warrants As of December 31, 2022, the Company had outstanding warrants to purchase common stock as follows: Total Outstanding and Exercisable Underlying Shares of Common Stock Exercise Price per Share Expiration Date Series 1 Warrants issued in the February 2018 Series B financing 8,979,000 44,895 $ 400.00 February 2025 Series 2 Warrants issued in the February 2018 Series B financing 8,709,500 43,548 $ 400.00 February 2025 Warrants issued in the November 2018 financing 8,768,395 43,842 $ 80.00 November 2023 Placement agent warrants issued in the January 2022 financing 1,330,000 66,500 $ 10.00 January 2027 Warrants issued in the January 2022 financing 16,150,000 807,500 $ 9.60 July 2027 Pre-funded warrants issued in the August 2022 financing 1,369,864 1,369,864 $ 0.0001 n/a Series A Preferred Investment Options issued in August 2022 financing 2,853,883 2,853,883 $ 1.502 February 2028 Series B Preferred Investment Options issued in August 2022 financing 2,853,883 2,853,883 $ 1.502 August 2024 Placement agent Preferred Investment Options issued in the August 2022 financing 171,233 171,233 $ 2.19 August 2027 Total as of December 31, 2022 51,185,758 8,255,148 As of December 31, 2021, the Company had outstanding warrants to purchase common stock as follows: Total Outstanding and Exercisable Underlying Shares of Common Stock Exercise Price per Share Expiration Date Series 1 Warrants issued in the February 2018 Series B financing 8,979,000 44,895 $ 400.00 February 2025 Series 2 Warrants issued in the February 2018 Series B financing 8,709,500 43,548 $ 400.00 February 2025 Warrants issued in the November 2018 financing 8,768,395 43,842 $ 80.00 November 2023 Total as of December 31, 2021 26,456,895 132,265 January 2022 Offering Pursuant to a purchase agreement entered into on January 14, 2022, the Company issued warrants to purchase up to an aggregate of 807,500 shares of the Company’s common stock at an exercise price of $9.60 per share and which became exercisable beginning July 14, 2022. The Common Warrants will expire five The Company issued to the placement agent of the January 2022 Offering warrants to purchase up to an aggregate of 66,500 shares of common stock (the “Placement Agent Warrants”). The Placement Agent Warrants are subject to the same terms as the Common Warrants, except that the Placement Agent Warrants have an exercise price of $10.00 per share and a term of five August 2022 Offering Pursuant to a purchase agreement entered into on August 4, 2022, the Company issued, in a registered direct offering, Pre-Funded Warrants to purchase up to 784,019 shares of common stock (the “RD Pre-Funded Warrants”) and, in a concurrent private placement, Pre-Funded Warrants to purchase up to 1,369,864 shares of common stock (the “Private Placement Pre-Funded Warrants” and together with the RD Pre-Funded Warrants the “August 2022 Pre-Funded Warrants”). The August 2022 Pre-Funded Warrants have an exercise price of $0.0001 per share, are immediately exercisable, and have no expiration date. During the year ended December 31, 2022, 784,019 of shares of RD Pre-Funded Warrants were exercised into the equivalent number of the Company’s common stock. As of December 31, 2022, August 2022 Pre-Funded Warrants exercisable for 1,369,864 shares of the Company’s common stock remained outstanding. On February 14, 2023, an additional 747,864 Private Placement Pre-Funded Warrants were exercised leaving 622,000 August 2022 Pre-Funded Warrants outstanding. Also in the August 2022 offering, the Company issued Series A preferred investment options to purchase up to 2,853,883 additional shares of the Company’s common stock and Series B preferred investment options to purchase up to 2,853,883 additional shares of the Company’s common stock, collectively referred to as Preferred Investment Options. The Series A preferred investment options have an exercise price of $1.502 per share, are immediately exercisable, and will expire five two The Company also issued to the placement agent of the August 2022 Offering preferred investment options to purchase up to 171,233 shares of common stock (the “Placement Agent Preferred Investment Options”). The Placement Agent Preferred Investment Options are subject to the same terms as the Preferred Investment Options, except that the Placement Agent Preferred Investment Options have an exercise price of $2.19 per share and a term of five The exercise price and the number of shares of common stock issuable upon exercise of each Common Warrants, Pre-Funded Warrants, Preferred Investment Options, and Placement Agent Preferred Investment Options are subject to appropriate adjustments in the event of certain stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting the common stock. In addition, in certain circumstances, upon a fundamental transaction, a holder of Common Warrants, Pre-Funded Warrants, Preferred Investment Options, or Placement Agent Preferred Investment Options will be entitled to receive, upon exercise, the kind and amount of securities, cash or other property that such holder would have received had they exercised the Common Warrants, Pre-Funded Warrants, Preferred Investment Options, or Placement Agent Preferred Investment Options immediately prior to the fundamental transaction. The Common Warrants, Pre-Funded Warrants, Preferred Investment Options, and Placement Agent Preferred Investment Options can be exercised at the option of the holders at any time after they become exercisable provided that shares of the Common Warrants, Pre-Funded Warrants, Preferred Investment Options, or Placement Agent Preferred Investment Options cannot be exercised into common stock if the applicable holder would beneficially own in excess of 4.99% (or, upon election by such holder prior to the issuance of any shares of Common Warrants, Pre-Funded Warrants, Preferred Investment Options, or Placement Agent Preferred Investment Options, 9.99 In the event of a fundamental transaction in which the holders of our voting securities immediately prior to such fundamental transaction will not, following such fundamental transaction, directly or indirectly own more than 50% of the voting securities of the surviving entity or successor entity, and in which the Company is not the successor entity or does not continue as a reporting issuer under the Exchange Act, then, at the request of the holder, the Company or the successor entity shall purchase the unexercised portion of the Common Warrants, Preferred Investment Options, and Placement Agent Preferred Investment Options from the holder by paying to the holder an amount, in cash, equal to the fair value of the remaining unexercised portion of the Common Warrants, Preferred Investment Options, and Placement Agent Preferred Investment Options on the date of such fundamental transaction, subject to certain limitations in the event of a fundamental transaction not within our control. As of December 31, 2022 and 2021, warrants and preferred investment options to purchase an aggregate of 8,255,148 and 132,265 shares of common stock were outstanding, respectively, all of which were classified within the equity section of the respective balance sheets.

Note 11 - Stock-based Compensat

Note 11 - Stock-based Compensation	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Share-Based Payment Arrangement [Text Block]	11. Stock-Based Compensation Stock Plans In January 2015, the Board of Directors adopted and the Company’s stockholders approved the 2015 Equity Incentive Plan (“2015 Plan”). The 2015 Plan provides for the grant of incentive stock options (“ISOs”) to employees and for the grant of non-statutory stock options (“NSOs”), restricted stock, restricted stock awards (“RSAs”), restricted stock units (“RSUs”), stock appreciation rights, performance units and performance shares to employees, directors and consultants. The shares reserved for issuance under the 2015 Plan includes share awards granted under the prior equity incentive plan that expire or terminate without having been exercised in full or that are forfeited or repurchased. On October 14, 2022, the Company’s stockholders approved an additional 1,750,000 shares of common stock for issuance under the 2015 Plan. As of December 31, 2022, 1,759,566 shares were available for grant under the 2015 Plan. Pursuant to the 2015 Plan, ISOs and NSOs may be granted with exercise prices at not less than 100% of the fair value of the common stock on the date of grant and the exercise price of ISOs granted to a stockholder, who, at the time of grant, owns stock representing more than 10% of the voting power of all classes of the stock of the Company, shall be not less than 110% of the fair market value per share of common stock on the date of grant. The Company’s Board of Directors determines the vesting schedule of the options. 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, 2020 307 $ 19,577.10 5.95 $ — Options expired (4 ) $ 36,000.00 Balance at December 31, 2021 303 $ 19,360.30 5.02 $ — Balance at December 31, 2022 303 $ 19,360.30 4.02 $ — Exercisable at December 31, 2022 303 $ 19,360.30 4.02 $ — Vested and expected to vest at December 31, 2022 303 $ 19,360.30 4.02 $ — Additional information related to the Company’s stock options as of December 31, 2022 is summarized as follows: Options Outstanding Options Vested Weighted Weighted Weighted Average Average Average Exercise Options Remaining Exercise Number Exercise Price Outstanding Contractual Life Price Exercisable Price $ 334.00 155 5.44 $ 334.00 155 $ 334.00 $ 16,400.00 - 28,400.00 31 4.18 $ 17,323.87 31 $ 17,323.87 $ 36,000.00 103 2.00 $ 36,000.00 103 $ 36,000.00 $ 103,680.00 - 162,000.00 14 2.85 $ 112,097.14 14 $ 112,097.14 303 4.02 $ 19,360.30 303 $ 19,360.30 There were no no not The Company’s RSUs generally vest annually over three Number of Shares Weighted Average Grant Date Fair Value Weighted Average Remaining Contractual Term Awards outstanding at December 31, 2020 20,671 $ 76.03 0.98 Awarded 4,500 $ 32.20 Released (13,386 ) $ 104.31 Forfeited (1,725 ) $ 53.62 Awards outstanding at December 31, 2021 10,060 $ 24.39 0.72 Released (8,590 ) $ 25.02 Forfeited (1,053 ) $ 24.25 Awards outstanding at December 31, 2022 417 $ 11.64 0.17 As of December 31, 2022, there was less than $0.1 million of remaining unamortized stock-based compensation expense associated with RSUs, which will be expensed over a weighted average remaining service period of 0.2 years. The outstanding non-vested and expected to vest RSUs at December 31, 2022 have an aggregate fair value of approximately less than $0.1 million. The Company used the closing market price of $1.09 per share at December 31, 2022 to determine the aggregate fair value for the RSUs outstanding at that date. For the years ended December 31, 2022 and 2021, the fair value of RSUs vested was approximately $14,000 and $273,000, respectively. For the years ended December 31, 2022 and 2021, stock-based compensation expense recognized associated with the vesting of RSUs was approximately $0.1 million and $1.0 million, respectively. 2018 Officer and Director Share Purchase Plan On August 22, 2018, the Board of Directors of the Company approved the adoption of an Officer and Director Share Purchase Plan (“ODPP”), which allowed executive officers and directors to purchase shares of our common stock at fair market value in lieu of salary or, in the case of directors, director fees. Eligible individuals were allowed voluntarily participate in the ODPP by authorizing payroll deductions or, in the case of directors, deductions from director fees for the purpose of purchasing common stock. There was no no Total noncash stock-based compensation expense relating to the Company’s stock options and RSUs recognized, before taxes, during the years ended December 31, 2022 and 2021, is as follows (in thousands): Year Ended December 31, 2022 2021 Cost of revenues $ 18 $ 101 Research and development expenses 37 287 Selling, general and administrative expenses 72 627 $ 127 $ 1,015

Note 12 - Income Taxes

Note 12 - Income Taxes	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Income Tax Disclosure [Text Block]	12. Income Taxes For the years ended December 31, 2022 and 2021, the Company’s provision for income taxes consisted of zero Year Ended December 31, 2022 2021 Tax at federal statutory rate $ (3,701 ) $ (3,657 ) State taxes, net of federal benefit (916 ) (711 ) Permanent differences (484 ) (445 ) Change in valuation allowance 5,084 5,104 Research credits (273 ) (286 ) Nondeductible interest expense 290 — Other — (5 ) Provision for taxes $ — $ — Significant components of the Company’s net deferred tax assets as of December 31, 2022 and 2021 consist of the following (in thousands): As of December 31, 2022 2021 Deferred tax assets: Federal, state and foreign net operating losses $ 85,547 $ 83,211 Research and other credits 5,343 4,892 Operating lease liability 544 752 Fixed assets 471 — Accruals and other 3,628 2,845 Capitalized research and development 1,019 — Total deferred tax assets 96,552 91,700 Less: Valuation allowance (95,992 ) (90,908 ) Total net deferred tax assets 560 792 Deferred liabilities: Property and equipment — (2 ) Operating lease right of use asset (560 ) (790 ) Total deferred tax liabilities (560 ) (792 ) Net deferred tax assets (liabilities) $ — $ — The valuation allowance increased by $5.1 million and $4.7 million during the years ended December 31, 2022 and 2021, respectively. As of December 31, 2022, the Company had approximately $344.3 million of federal and $208.0 million of state net operating loss carryforwards available to offset future taxable income. If not utilized, the federal and state net operating loss carryforwards begin to expire in 2027 and 2023, respectively. Out of the Federal net operating loss carryforwards, $86.8 million were generated post December 31, 2017 and have no expiration. As of December 31, 2022, the Company also had approximately $4.3 million and $4.2 million of research and development tax credit carryforwards available to reduce future taxable income, if any, for both federal and California purposes, respectively. The federal credit carryforwards expire beginning in 2027, and the California research credits do not expire and may be carried forward indefinitely. The Company's ability to utilize the net operating loss and tax credit carryforwards in the future may be subject to substantial restrictions in the event of past or future ownership changes as defined in Section 382 of the Internal Revenue Code and similar state tax laws. In the event the Company should experience an ownership change, as defined, utilization of the Company's net operating loss carryforwards and tax credits could be limited. The Company evaluates tax positions for recognition using a more-likely-than-not recognition threshold, and those tax positions eligible for recognition are measured as the largest amount of tax benefit that is greater than 50% likely of being realized upon the effective settlement with a taxing authority that has full knowledge of all relevant information. A reconciliation of the beginning and ending amount of the gross recognized tax benefit is as follows (in thousands): As of December 31, 2022 2021 Balance at beginning of year $ 2,366 $ 2,307 Increase based on the tax positions in the current year 203 228 Increase (Decrease) for tax positions of prior year 12 (169 ) Balance at end of year $ 2,581 $ 2,366 As of December 31, 2022, all unrecognized tax benefits would be subject to a full valuation allowance, if recognized, and would not affect the Company’s tax rate. The Company does not anticipate that the total amounts of unrecognized tax benefits will significantly increase or decrease in the next twelve months. 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

Note 13 - 401(k) Plan

Note 13 - 401(k) Plan	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Retirement Benefits [Text Block]	13. 401(k) Plan The Company has a qualified retirement plan under section 401(k) of the Internal Revenue Code (“IRC”) under which participants may contribute up to 99% of their eligible compensation, subject to maximum deferral limits specified by the IRC. The Company may make a discretionary matching contribution to the 401(k) plan, and may make a discretionary employer contribution to each eligible employee each year. To date, the Company has made no

Note 14 - Subsequent Events

Note 14 - Subsequent Events	12 Months Ended
	Dec. 31, 2022
Notes to Financial Statements
Subsequent Events [Text Block]	14. Subsequent Events Pre-Funded Warrant Exercise On February 14, 2023, a holder of Private Placement Pre-Funded Warrants opted to exercise a portion of the warrant into common stock. A total of 747,864 shares of the Private Placement Pre-Funded Warrants were exercised resulting in the issuance of an aggregate of 747,864 shares of common stock. After giving effect to these aforementioned exercise, there remains 622,000 shares of Private Placement Pre-Funded Warrant shares outstanding, which if exercised, would result in the issuance of an equivalent number of shares of common stock. Restricted Stock Award Grant On January 18, 2023, the Company granted a total of 1,502,928 shares of RSAs to various employees. These RSAs generally vest annually over two Silicon Valley Bank Currently all of our cash and cash equivalents are held at a single financial institution, Silicon Valley Bank. On March 10, 2023, the Federal Deposit Insurance Corporation announced that Silicon Valley Bank had been closed by the California Department of Financial Protection and Innovation. While we have regained access to our accounts at Silicon Valley Bank and are evaluating our banking relationships, future disruptions of financial institutions where we bank or have credit arrangements, or disruptions of the financial services industry in general, could adversely affect our ability to access our cash and cash equivalents. If we are unable to access our cash and cash equivalents as needed, our financial position and ability to operate our business will be adversely affected.

Significant Accounting Policies

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Accounting Policies [Abstract]
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation
Use of Estimates, Policy [Policy Text Block]	Use of Estimates
Fair Value Measurement, Policy [Policy Text Block]	Fair Value of Financial Instruments
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents no
Concentration of Credit Risk and Other Risks and Uncertainties [Policy Text Block]	Concentration of Credit Risk, and Other Risks and Uncertainties no one one
Receivable [Policy Text Block]	Accounts Receivable 2022 2021 Beginning balance $ 6 $ 19 Provision 70 2 Recoveries/write-offs (3 ) (15 ) Ending balance $ 73 $ 6
Inventory, Policy [Policy Text Block]	Inventories
Property, Plant and Equipment, Policy [Policy Text Block]	Property and Equipment three five
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	Impairment of Long-Lived Assets
Revenue [Policy Text Block]	Revenue Recognition Leases Revenue from Contracts with Customers (Topic 606)
Cost of Goods and Service [Policy Text Block]	Cost of Revenues
Standard Product Warranty, Policy [Policy Text Block]	Product Warranty Costs one 2022 2021 Beginning balance $ 187 $ 193 Warranty provision 22 49 Usage/Release (100 ) (55 ) Ending balance $ 109 $ 187
Research and Development Expense, Policy [Policy Text Block]	Research and Development
Clinical Trials [Policy Text Block]	Clinical Trials
Share-Based Payment Arrangement [Policy Text Block]	Stock-Based Compensation Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting
Foreign Currency Transactions and Translations Policy [Policy Text Block]	Foreign Currency
Income Tax, Policy [Policy Text Block]	Income Taxes not
Earnings Per Share, Policy [Policy Text Block]	Net Loss per Share Attributable to Common Stockholders no Year Ended December 31, 2022 2021 Net loss applicable to common stockholders $ (27,244 ) $ (21,587 ) Weighted average common stock outstanding, basic and diluted 6,249 4,722 Net loss per share attributable to common stockholders, basic and diluted $ (4.36 ) $ (4.57 ) Year Ended December 31, 2022 2021 Common stock warrants equivalents 4,009,679 135,429 Common stock options 303 304 Convertible preferred stock 58,080 52,289 Unvested restricted stock units 6,626 17,817 4,074,688 205,839
Comprehensive Income, Policy [Policy Text Block]	Comprehensive Loss
Segment Reporting, Policy [Policy Text Block]	Segment and Geographical Information one
New Accounting Pronouncements, Policy [Policy Text Block]	Recent Accounting Pronouncements Recently adopted accounting standards Issuer s Accounting for Certain Modifications of Exchanges of Freestanding Equity-Classified Written Call Options Recent accounting standards not yet adopted Debt Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging Contracts in Entity s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity s Own Equity

Financial Statements Schedules

Financial Statements Schedules (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Tables
Valuation Allowances and Reserves [Table Text Block]	Description Balance at Beginning of Year Charged to costs and expenses Write offs Balance at End of Year Allowance for doubtful accounts receivable: Fiscal year ended 2021 $ 19 $ 2 $ 15 $ 6 Fiscal year ended 2022 $ 6 $ 70 $ 3 $ 73 Balance at Beginning of Year Charged to costs and expenses Write offs Balance at End of Year Allowance for sales returns: Fiscal year ended 2021 $ 20 $ 10 $ 10 $ 20 Fiscal year ended 2022 $ 20 $ — $ 5 $ 15

Note 2 - Summary of Significa_2

Note 2 - Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Tables
Accounts Receivable, Allowance for Credit Loss [Table Text Block]	2022 2021 Beginning balance $ 6 $ 19 Provision 70 2 Recoveries/write-offs (3 ) (15 ) Ending balance $ 73 $ 6
Schedule of Product Warranty Liability [Table Text Block]	2022 2021 Beginning balance $ 187 $ 193 Warranty provision 22 49 Usage/Release (100 ) (55 ) Ending balance $ 109 $ 187
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Year Ended December 31, 2022 2021 Net loss applicable to common stockholders $ (27,244 ) $ (21,587 ) Weighted average common stock outstanding, basic and diluted 6,249 4,722 Net loss per share attributable to common stockholders, basic and diluted $ (4.36 ) $ (4.57 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	Year Ended December 31, 2022 2021 Common stock warrants equivalents 4,009,679 135,429 Common stock options 303 304 Convertible preferred stock 58,080 52,289 Unvested restricted stock units 6,626 17,817 4,074,688 205,839

Note 4 - Inventories (Tables)

Note 4 - Inventories (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Tables
Schedule of Inventory, Current [Table Text Block]	December 31, 2022 2021 Raw materials $ 3,374 $ 2,503 Work-in-process 17 1 Finished products 1,574 2,097 Total inventories $ 4,965 $ 4,601

Note 5 - Property and Equipme_2

Note 5 - Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Tables
Property, Plant and Equipment [Table Text Block]	December 31, 2022 2021 Equipment held by customers and field sales personnel $ 2,566 $ 2,362 Machinery and equipment 1,372 1,391 Computer software 122 122 Computer equipment 200 173 Furniture and fixture 78 78 Leasehold improvements 320 320 Total property and equipment, gross 4,658 4,446 Less: Accumulated depreciation and amortization (3,956 ) (4,351 ) Total property and equipment, net $ 702 $ 95

Note 7 - Borrowings (Tables)

Note 7 - Borrowings (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Tables
Schedule of Debt [Table Text Block]	Year Ending December 31, 2023 $ — 2024 9,045 2025 10,339 Total 19,384 Less: Amount of PIK additions and final facility fee to be incurred subsequent to December 31, 2022 (4,970 ) Less: Amount representing debt issuance costs (249 ) Borrowings, current portion, as of December 31, 2022 $ 14,165

Note 8 - Leases (Tables)

Note 8 - Leases (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Tables
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	Year Ending December 31, 2023 $ 1,203 2024 1,138 Total 2,341 Less: Imputed interest (147 ) Leasehold liability as of December 31, 2022 $ 2,194
Right of Use Asset and Liabilities [Table Text Block]	December 31, Lease-Related Assets and Liabilities Financial Statement Line Items 2022 2021 Right of use assets: Operating lease Right of use asset $ 2,194 $ 3,179 Total right of use assets $ 2,194 $ 3,179 Lease liabilities: Operating lease Leasehold liability, current portion $ 1,092 $ 985 Leasehold liability, long-term portion 1,102 2,194 Total lease liabilities $ 2,194 $ 3,179

Note 10 - Stockholders' Equity

Note 10 - Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Tables
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]	Total Outstanding and Exercisable Underlying Shares of Common Stock Exercise Price per Share Expiration Date Series 1 Warrants issued in the February 2018 Series B financing 8,979,000 44,895 $ 400.00 February 2025 Series 2 Warrants issued in the February 2018 Series B financing 8,709,500 43,548 $ 400.00 February 2025 Warrants issued in the November 2018 financing 8,768,395 43,842 $ 80.00 November 2023 Placement agent warrants issued in the January 2022 financing 1,330,000 66,500 $ 10.00 January 2027 Warrants issued in the January 2022 financing 16,150,000 807,500 $ 9.60 July 2027 Pre-funded warrants issued in the August 2022 financing 1,369,864 1,369,864 $ 0.0001 n/a Series A Preferred Investment Options issued in August 2022 financing 2,853,883 2,853,883 $ 1.502 February 2028 Series B Preferred Investment Options issued in August 2022 financing 2,853,883 2,853,883 $ 1.502 August 2024 Placement agent Preferred Investment Options issued in the August 2022 financing 171,233 171,233 $ 2.19 August 2027 Total as of December 31, 2022 51,185,758 8,255,148 Total Outstanding and Exercisable Underlying Shares of Common Stock Exercise Price per Share Expiration Date Series 1 Warrants issued in the February 2018 Series B financing 8,979,000 44,895 $ 400.00 February 2025 Series 2 Warrants issued in the February 2018 Series B financing 8,709,500 43,548 $ 400.00 February 2025 Warrants issued in the November 2018 financing 8,768,395 43,842 $ 80.00 November 2023 Total as of December 31, 2021 26,456,895 132,265

Note 11 - Stock-based Compens_2

Note 11 - Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Tables
Share-Based Payment Arrangement, Option, Activity [Table Text Block]	Number of Shares (in thousands) Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in years) Intrinsic Value (in thousands) Balance at December 31, 2020 307 $ 19,577.10 5.95 $ — Options expired (4 ) $ 36,000.00 Balance at December 31, 2021 303 $ 19,360.30 5.02 $ — Balance at December 31, 2022 303 $ 19,360.30 4.02 $ — Exercisable at December 31, 2022 303 $ 19,360.30 4.02 $ — Vested and expected to vest at December 31, 2022 303 $ 19,360.30 4.02 $ —
Share-Based Payment Arrangement, Option, Exercise Price Range [Table Text Block]	Options Outstanding Options Vested Weighted Weighted Weighted Average Average Average Exercise Options Remaining Exercise Number Exercise Price Outstanding Contractual Life Price Exercisable Price $ 334.00 155 5.44 $ 334.00 155 $ 334.00 $ 16,400.00 - 28,400.00 31 4.18 $ 17,323.87 31 $ 17,323.87 $ 36,000.00 103 2.00 $ 36,000.00 103 $ 36,000.00 $ 103,680.00 - 162,000.00 14 2.85 $ 112,097.14 14 $ 112,097.14 303 4.02 $ 19,360.30 303 $ 19,360.30
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, 2020 20,671 $ 76.03 0.98 Awarded 4,500 $ 32.20 Released (13,386 ) $ 104.31 Forfeited (1,725 ) $ 53.62 Awards outstanding at December 31, 2021 10,060 $ 24.39 0.72 Released (8,590 ) $ 25.02 Forfeited (1,053 ) $ 24.25 Awards outstanding at December 31, 2022 417 $ 11.64 0.17
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]	Year Ended December 31, 2022 2021 Cost of revenues $ 18 $ 101 Research and development expenses 37 287 Selling, general and administrative expenses 72 627 $ 127 $ 1,015

Note 12 - Income Taxes (Tables)

Note 12 - Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2022
Notes Tables
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Year Ended December 31, 2022 2021 Tax at federal statutory rate $ (3,701 ) $ (3,657 ) State taxes, net of federal benefit (916 ) (711 ) Permanent differences (484 ) (445 ) Change in valuation allowance 5,084 5,104 Research credits (273 ) (286 ) Nondeductible interest expense 290 — Other — (5 ) Provision for taxes $ — $ —
Schedule of Deferred Tax Assets and Liabilities [Table Text Block]	As of December 31, 2022 2021 Deferred tax assets: Federal, state and foreign net operating losses $ 85,547 $ 83,211 Research and other credits 5,343 4,892 Operating lease liability 544 752 Fixed assets 471 — Accruals and other 3,628 2,845 Capitalized research and development 1,019 — Total deferred tax assets 96,552 91,700 Less: Valuation allowance (95,992 ) (90,908 ) Total net deferred tax assets 560 792 Deferred liabilities: Property and equipment — (2 ) Operating lease right of use asset (560 ) (790 ) Total deferred tax liabilities (560 ) (792 ) Net deferred tax assets (liabilities) $ — $ —
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]	As of December 31, 2022 2021 Balance at beginning of year $ 2,366 $ 2,307 Increase based on the tax positions in the current year 203 228 Increase (Decrease) for tax positions of prior year 12 (169 ) Balance at end of year $ 2,581 $ 2,366

Financial Statements Schedule_2

Financial Statements Schedules - Allowance of Doubtful Accounts and Sales Returns (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-09, Allowance, Sales Returns [Member]
Balance at Beginning of Year	$ 20	$ 20
Charged to costs and expenses, additions	0	10
Write offs	5	10
Balance at End of Year	15	20
SEC Schedule, 12-09, Allowance, Credit Loss [Member]
Balance at Beginning of Year	6	19
Charged to costs and expenses, additions	70	2
Write offs	3	15
Balance at End of Year	$ 73	$ 6

Note 1 - Organization (Details

Note 1 - Organization (Details Textual) - USD ($)				1 Months Ended		12 Months Ended
	Aug. 04, 2022	Jan. 14, 2022	Feb. 02, 2021	Aug. 31, 2022	Feb. 28, 2021	Dec. 31, 2022	May 20, 2022	Dec. 31, 2021
Retained Earnings (Accumulated Deficit), Total						$ (402,376,000)		$ (384,753,000)
Cash and Cash Equivalents, at Carrying Value, Total						$ 14,603,000		$ 19,497,000
Share Price						$ 1.09
Preferred Stock, Par or Stated Value Per Share						$ 0.001		$ 0.001
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						8,255,148		132,265
Class of Warrant or Right, Outstanding						51,185,758		26,456,895
Common Stock, Par or Stated Value Per Share (in dollars per share)						$ 0.001		$ 0.001
Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		807,500
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 9.60
Warrants and Rights Outstanding, Term		5 years
Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		66,500				66,500
Class of Warrant or Right, Outstanding						1,330,000
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 10				$ 10
Warrants and Rights Outstanding, Term		5 years
Registered Direct Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	784,019
Pre-funded Warrants [Member]
Class of Warrant or Right, Outstanding						622,000
Series A Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				2,853,883
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 1.502
Warrants and Rights Outstanding, Term				5 years 6 months
Series B Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				2,853,883
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 1.502
Warrants and Rights Outstanding, Term				2 years
Placement Agent Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				171,233
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 2.19
Warrants and Rights Outstanding, Term				5 years
Series D Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share		$ 0.001
Series D Preferred Stock [Member] | Common Warrants [Member]
Class of Warrant or Right, Outstanding		807,500
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 9.60
Warrants and Rights Outstanding, Term		5 years
Series D Preferred Stock [Member] | Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		66,500
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 10
Warrants and Rights Outstanding, Term		5 years
August 2022 Public Offering [Member]
Proceeds from Issuance or Sale of Equity, Net				$ 4,400,000
The Market Offering Agreement (the “ATM Agreement”) [Member]
Proceeds from Issuance or Sale of Equity, Net						$ 800,000
January 2022 Public Offering [Member]
Proceeds from Issuance or Sale of Equity, Net		$ 6,700,000				$ 6,700,000
January 2022 Public Offering [Member] | Series D Preferred Stock [Member]
Stock Issued During Period, Shares, New Issues		7,600
Preferred Stock, Par or Stated Value Per Share		$ 1,000
Preferred Stock, Convertible, Conversion Price		$ 8
February 2021 Public Offering [Member]
Proceeds from Issuance or Sale of Equity, Net			$ 13,000,000		$ 13,000,000
Stock Issued During Period, Shares, New Issues			500,000
Share Price			$ 28.80
August 2022 Purchase Agreement [Member]
Stock Issued During Period, Shares, New Issues	700,000
Sale of Stock, Number of Shares (in shares)	1,484,019
Shares Issued, Price Per Share (in dollars per share)	$ 1.752
Proceeds from Issuance or Sale of Equity, Total	$ 4,400,000
Private Placement [Member]
Stock Issued During Period, Shares, New Issues	1,369,864
Shares Issued, Price Per Share (in dollars per share)	$ 1.752
Private Placement [Member] | Registered Direct Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights	1,369,864
Common Stock in June, 2022 [Member]
Stock Issued During Period, Shares, New Issues						585,603
Shares Issued, Price Per Share (in dollars per share)						$ 1.67
Proceeds from Issuance or Sale of Equity, Total						$ 1,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)							$ 0.001
Share Offering Agreement, Aggregate Offering							$ 7,000,000
Commission Percentage							3%
Payments of Stock Issuance Costs						$ 29,000

Note 2 - Summary of Significa_3

Note 2 - Summary of Significant Accounting Policies (Details Textual) shares in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 11, 2022	Jan. 31, 2022 USD ($)	Mar. 31, 2022	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares
Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain (Loss), before Tax, Total				$ 0	$ 0
Warranty Period (Year)				1 year
Foreign Currency Transaction Gain (Loss), before Tax, Total		$ 12,000			16,000
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
Number of Reportable Segments				1
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)				3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)				5 years
Customer Concentration Risk [Member] | Accounts Receivable [Member]
Number of Major Customers				0	1
Customer Concentration Risk [Member] | Accounts Receivable [Member] | One Customer [Member]
Concentration Risk, Percentage					21%
Customer Concentration Risk [Member] | Revenue Benchmark [Member]
Number of Major Customers				1	1
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | UNITED STATES
Concentration Risk, Percentage				92%	94%
Customer Concentration Risk [Member] | Revenue Benchmark [Member] | One Customer [Member]
Concentration Risk, Percentage			14%		10%
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio	20

Note 2 - Summary of Significa_4

Note 2 - Summary of Significant Accounting Policies - Accounts Receivable, Allowance for Credit Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Beginning balance	$ 6	$ 19
Provision	70	2
Recoveries/write-offs	(3)	(15)
Ending balance	$ 73	$ 6

Note 2 - Summary of Significa_5

Note 2 - Summary of Significant Accounting Policies - Product Warranty (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Beginning balance	$ 187	$ 193
Warranty provision	22	49
Usage/Release	(100)	(55)
Ending balance	$ 109	$ 187

Note 2 - Summary of Significa_6

Note 2 - Summary of Significant Accounting Policies - Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Net loss applicable to common stockholders	$ (27,244)	$ (21,587)
Weighted average common stock outstanding, basic and diluted (in shares)	6,249	4,722
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (4.36)	$ (4.57)

Note 2 - Summary of Significa_7

Note 2 - Summary of Significant Accounting Policies - Anti-dilutive Securities (Details) - shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities (in shares)	4,074,688	205,839
Common Stock Warrants [Member]
Antidilutive Securities (in shares)	4,009,679	135,429
Common Stock Options [ member]
Antidilutive Securities (in shares)	303	304
Preferred Stock [Member]
Antidilutive Securities (in shares)	58,080	52,289
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities (in shares)	6,626	17,817

Note 3 - Fair Value Measureme_2

Note 3 - Fair Value Measurements (Details Textual) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Inputs, Level 2 [Member]
Assets, Fair Value Disclosure, Total	$ 0	$ 0
Liabilities, Fair Value Disclosure, Total	0	0
Fair Value, Inputs, Level 3 [Member]
Assets, Fair Value Disclosure, Total	0	0
Liabilities, Fair Value Disclosure, Total	$ 0	$ 0

Note 4 - Inventories - Schedule

Note 4 - Inventories - Schedule of Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Raw materials	$ 3,374	$ 2,503
Work-in-process	17	1
Finished products	1,574	2,097
Total inventories	$ 4,965	$ 4,601

Note 5 - Property and Equipme_3

Note 5 - Property and Equipment, Net (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Depreciation, Total	$ 196,000	$ 687,000
Property, Plant, and Equipment, Lessor Asset under Operating Lease, after Accumulated Depreciation, Total	527,000	0
Leased Equipment [Member]
Cost, Depreciation	$ 119,000	$ 539,000

Note 5 - Property and Equipme_4

Note 5 - Property and Equipment, Net - Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property and Equipment	$ 4,658	$ 4,446
Less: Accumulated depreciation and amortization	(3,956)	(4,351)
Total property and equipment, net	702	95
Equipment Held by Customers [Member]
Property and Equipment	2,566	2,362
Machinery and Equipment [Member]
Property and Equipment	1,372	1,391
Software Development [Member]
Property and Equipment	122	122
Computer Equipment [Member]
Property and Equipment	200	173
Furniture and Fixtures [Member]
Property and Equipment	78	78
Leasehold Improvements [Member]
Property and Equipment	$ 320	$ 320

Note 6 - Accrued Expenses and_2

Note 6 - Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred revenue	$ 141	$ 123
Accrued travel and entertainment expenses	129	118
Accrued product warranty costs	109	187
Accrued clinical trial costs	106	153
Accrued professional fees	60	0
Accrued sales and use tax	40	33
Other accrued liabilities	72	104
Total accrued expenses and other current liabilities	$ 657	$ 718

Note 7 - Borrowings (Details Te

Note 7 - Borrowings (Details Textual) - USD ($)				1 Months Ended	12 Months Ended
	Aug. 10, 2022	Apr. 23, 2020	Feb. 14, 2018	Apr. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Jun. 15, 2016	Sep. 22, 2015
Gain (Loss) on Extinguishment of Debt, Total					$ 0	$ 2,353,000
Interest Expense, Total					1,665,000	1,648,000
Paycheck Protection Program CARES Act [Member]
Proceeds from Issuance of Long-Term Debt, Total		$ 2,300,000
Debt Instrument Interest Forgiven				$ 23,000
Interest Expense, Total					7,000
Paycheck Protection Program CARES Act [Member] | Other Nonoperating Income (Expense) [Member]
Gain (Loss) on Extinguishment of Debt, Total				$ 2,400,000
CRG [Member] | Loan Agreement [Member]
Debt Agreement, Maximum Borrowing Capacity								$ 50,000,000
Debt Instrument, Covenant Compliance, Minimum Liquidity Requirement			$ 3,500,000
Debt Instrument, Covenant Compliance, Target Minimum Revenue, Past Twelve Months	$ 8,000,000
Debt Instrument, Covenant Compliance Target Minimum Revenue, Next Twelve Months	8,000,000
Debt Instrument Covenant Compliance Target Minimum Revenue Second Year	10,000,000
Debt Instrument Covenant Compliance Target Minimum Revenue Third Year	14,500,000
Debt Instrument, Covenant Compliance Target Minimum Revenue Fourth Year	$ 17,000,000
Debt Instrument, Interest Rate, Stated Percentage	12.50%
Debt Instrument, Periodic Payment, Total	$ 1,900,000
Long-Term Debt, Maturity, Year Four	7,500,000
Long-Term Debt, Maturity, Year Five	$ 7,500,000
Debt Instrument, Redemption Initial Prepayment Premium Percentage	5%
Debt Instrument, Redemption Annual Decline in Prepayment Premium Percentage	1%
Debt Instrument, Financing Fee Percentage	1.50%
Debt Instrument, Final Facility Fee Percentage	15%
Debt Instrument, Covenant Compliance Cash and Certain Cash Equivalents Minimum	$ 3,500,000
Debt Instrument, Covenant Compliance Prepayment Multiplier for Revenue Shortfall	2
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net, Total					249,000	332,000		1,300,000
Amortization of Debt Discount (Premium)					83,000	86,000
Interest Expense, Debt, Total					$ 1,900,000	$ 1,600,000
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
CRG [Member] | Loan Agreement [Member] | First Tranche, Borrowed on September 22, 2015 [Member]
Debt Instrument, Face Amount								$ 30,000,000
CRG [Member] | Loan Agreement [Member] | Second Tranche, Borrowed on June 15, 2016 [Member]
Debt Instrument, Face Amount							$ 10,000,000

Note 7 - Borrowings - Schedule

Note 7 - Borrowings - Schedule of Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
2023	$ 0
Borrowings, current portion, as of December 31, 2022	14,165	$ 0
CRG [Member] | Loan Agreement [Member]
2024	9,045
2025	10,339
Total	19,384
Less: Amount of PIK additions and final facility fee to be incurred subsequent to December 31, 2022	(4,970)
Less: Amount representing debt issuance costs	(249)
Borrowings, current portion, as of December 31, 2022	$ 14,165

Note 8 - Leases (Details Textua

Note 8 - Leases (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Apr. 01, 2019
Lessee, Operating Lease, Liability, to be Paid, Total	$ 2,341,000		$ 5,800,000
Operating Lease, Weighted Average Remaining Lease Term	1 year 10 months 24 days
Lessee, Operating Lease, Discount Rate	6.50%
Operating Lease, Expense, Excluding Maintenance Fee and Other Expense, Monthly	$ 105,000
Operating Lease, Expense	314,000,000,000	$ 314,000,000,000
Variable Lease, Cost	300,000	200,000
Operating Lease, Right-of-Use Asset, Amortization Expense	1,100,000	1,000,000
Prepaid Rent	$ 65,000	$ 158,000

Note 8 - Leases - Future Operat

Note 8 - Leases - Future Operating Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Apr. 01, 2019
2023	$ 1,203
2024	1,138
Total	2,341		$ 5,800
Less: Imputed interest	(147)
Leasehold liability as of December 31, 2022	$ 2,194	$ 3,179

Note 8 - Leases - ROU Assets an

Note 8 - Leases - ROU Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Operating lease	$ 2,194	$ 3,179
Total right of use assets	2,194	3,179
Leasehold liability, current portion	1,092	985
Operating Lease, Liability, Noncurrent	1,102	2,194
Total lease liabilities	$ 2,194	$ 3,179

Note 9 - Commitments and Cont_2

Note 9 - Commitments and Contingencies (Details Textual) $ in Millions	Dec. 31, 2022 USD ($)
Purchase Commitment [Member]
Purchase Obligation, Total	$ 1.1

Note 10 - Stockholders' Equit_2

Note 10 - Stockholders' Equity (Details Textual) - USD ($)				12 Months Ended
	Feb. 14, 2023	Jan. 14, 2022	Feb. 14, 2018	Dec. 31, 2022	Dec. 31, 2021	Aug. 31, 2022	Aug. 04, 2022	Feb. 16, 2018
Preferred Stock, Shares Authorized				5,000,000	5,000,000
Preferred Stock, Par or Stated Value Per Share				$ 0.001	$ 0.001
Preferred Stock, Shares Issued				60,961	56,451
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				60,961	56,451
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				8,255,148	132,265
Preferred Stock Redemption Discount				$ 5,111,000	$ 0
Common Stock, Shares Authorized				100,000,000	100,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share)				$ 0.001	$ 0.001
Common Stock, Shares, Issued (in shares)				7,832,644	4,778,263
Common Stock, Shares, Outstanding, Ending Balance (in shares)				7,832,644	4,778,263
Class of Warrant or Right, Outstanding				51,185,758	26,456,895
Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input		5.5
Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input		1.3661
Measurement Input, Discount Rate [Member]
Warrants and Rights Outstanding, Measurement Input		0.0151
Measurement Input, Expected Dividend Rate [Member]
Warrants and Rights Outstanding, Measurement Input		0
Common Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		807,500
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 9.60
Warrants and Rights Outstanding, Term		5 years
Common Stock Warrants, Issued with Series D Convertible Preferred Stock [Member]
Proceeds from Issuance of Warrants		$ 3,600,000
Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		66,500		66,500
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 10		$ 10
Warrants and Rights Outstanding, Term		5 years
Class of Warrant or Right, Outstanding				1,330,000
Registered Direct Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							784,019
Stock Issued During Period, Shares, Warrants Exercised				784,019
Private Pre-funded Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights							1,369,864
Private Pre-funded Warrants [Member] | Subsequent Event [Member]
Stock Issued During Period, Shares, Warrants Exercised	747,864
Class of Warrant or Right, Outstanding	622,000
Class of Warrant or Right, Exercised (in shares)	747,864
Pre-funded Warrants Issued in August 2022 Financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights				1,369,864
Class of Warrant or Right, Exercise Price of Warrants or Rights				$ 0.0001			$ 0.0001
Class of Warrant or Right, Outstanding				1,369,864
Series A Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						2,853,883
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 1.502
Warrants and Rights Outstanding, Term						5 years 6 months
Series B Financing Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						2,853,883
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 1.502
Warrants and Rights Outstanding, Term						2 years
Placement Agent Preferred Investment Options [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						171,233
Class of Warrant or Right, Exercise Price of Warrants or Rights						$ 2.19
Warrants and Rights Outstanding, Term						5 years
January 2022 Public Offering [Member]
Proceeds from Issuance of Convertible Preferred Stock		$ 4
Conversion of Series B Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted					93
Conversion of Stock, Shares Issued					18,600
Conversion of Series D Preferred Stock into Common Stock [Member]
Conversion of Stock, Shares Converted				7,600
Conversion of Stock, Shares Issued				950,000
Series A Preferred Stock [Member]
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				60,876	56,366
Preferred Stock, Liquidation Preference Per Share				$ 1,000
Preferred Stock, Convertible, Conversion Price				$ 400
Dividends, Preferred Stock, Total				$ 4,500,000	$ 4,200,000
Series A Preferred Stock [Member] | CRG [Member]
Preferred Stock Dividends, Shares				4,510	4,175
Series A Preferred Stock [Member] | Conversion of Principal Amount of Senior Secured Loan to Newly Authorized Series A Preferred Stock [Member]
Preferred Stock, Dividend Rate, Percentage			8%
Series B Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share								$ 0.001
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				85	85
Preferred Stock, Convertible, Conversion Price				$ 1.502	$ 1.502
Series D Preferred Stock [Member]
Preferred Stock, Par or Stated Value Per Share		$ 0.001
Preferred Stock, Shares Outstanding, Ending Balance (in shares)				0
Series D Preferred Stock [Member] | Common Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 9.60
Warrants and Rights Outstanding, Term		5 years
Class of Warrant or Right, Outstanding		807,500
Series D Preferred Stock [Member] | Placement agent warrants issued in the January 2022 financing [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		66,500
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 10
Warrants and Rights Outstanding, Term		5 years
Series D Preferred Stock [Member] | January 2022 offering [Member]
Preferred Stock, Par or Stated Value Per Share		$ 0.001
Preferred Stock, Convertible, Conversion Price		$ 8
Stock Issued During Period, Shares, New Issues		7,600
Shares Issued, Price Per Share (in dollars per share)		$ 1,000
Preferred Stock, Convertible, Shares Issuable		950,000
Series D Preferred Stock [Member] | January 2022 offering [Member] | Common Warrants [Member]
Conversion of Warrants Allowed Maximum Ownership of Common Stock Percentage		4.99%
Conversion of Warrants Allowed Maximum Ownership of Common Stock Percentage upon Election		9.99%
Series D Preferred Stock [Member] | January 2022 Public Offering [Member]
Preferred Stock, Par or Stated Value Per Share		$ 1,000
Preferred Stock, Convertible, Conversion Price		$ 8
Stock Issued During Period, Shares, New Issues		7,600

Note 10 - Stockholder's Equity

Note 10 - Stockholder's Equity - Outstanding Warrants (Details) - $ / shares	Dec. 31, 2022	Aug. 04, 2022	Jan. 14, 2022	Dec. 31, 2021
Total outstanding and exercisable (in shares)	51,185,758			26,456,895
Underlying shares of common stock (in shares)	8,255,148			132,265
Series 1 February 2018 Warrants [Member]
Total outstanding and exercisable (in shares)	8,979,000			8,979,000
Underlying shares of common stock (in shares)	44,895			44,895
Exercise price per share (in dollars per share)	$ 400			$ 400
Series 2 February 2018 Warrants [Member]
Total outstanding and exercisable (in shares)	8,709,500			8,709,500
Underlying shares of common stock (in shares)	43,548			43,548
Exercise price per share (in dollars per share)	$ 400			$ 400
November 2018 Warrants [Member]
Total outstanding and exercisable (in shares)	8,768,395			8,768,395
Underlying shares of common stock (in shares)	43,842			43,842
Exercise price per share (in dollars per share)	$ 80			$ 80
Placement agent warrants issued in the January 2022 financing [Member]
Total outstanding and exercisable (in shares)	1,330,000
Underlying shares of common stock (in shares)	66,500		66,500
Exercise price per share (in dollars per share)	$ 10		$ 10
Warrants Issued in the January 2022 Financing [Member]
Total outstanding and exercisable (in shares)	16,150,000
Underlying shares of common stock (in shares)	807,500
Exercise price per share (in dollars per share)	$ 9.60
Pre-funded Warrants Issued in August 2022 Financing [Member]
Total outstanding and exercisable (in shares)	1,369,864
Underlying shares of common stock (in shares)	1,369,864
Exercise price per share (in dollars per share)	$ 0.0001	$ 0.0001
Series A Private Investment Options Issued in August 2022 Financing [Member]
Total outstanding and exercisable (in shares)	2,853,883
Underlying shares of common stock (in shares)	2,853,883
Exercise price per share (in dollars per share)	$ 1.502
Series B Private Investment Options Issued in August 2022 Financing [Member]
Total outstanding and exercisable (in shares)	2,853,883
Underlying shares of common stock (in shares)	2,853,883
Exercise price per share (in dollars per share)	$ 1.502
Placement Agent Private Investment Options Issued in August 2022 Financing [Member]
Total outstanding and exercisable (in shares)	171,233
Underlying shares of common stock (in shares)	171,233
Exercise price per share (in dollars per share)	$ 2.19

Note 11 - Stock-based Compens_3

Note 11 - Stock-based Compensation (Details Textual) - USD ($)		12 Months Ended
	Oct. 14, 2022	Dec. 31, 2022	Dec. 31, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period (in shares)		0	0
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)		0	0
Share-Based Payment Arrangement, Expense		$ 127,000	$ 1,015,000
Share Price		$ 1.09
Common Stock, Shares, Issued (in shares)		7,832,644	4,778,263
Share-Based Payment Arrangement, Option [Member]
Share-Based Payment Arrangement, Expense		$ 0	$ 4,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total		0
Share-Based Payment Arrangement, Expense, Tax Benefit		0	0
Restricted Stock Units (RSUs) [Member]
Share-Based Payment Arrangement, Expense		100,000	1,000,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total		$ 100,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition		2 months 12 days
Sharebased Compensation Arrangement by Sharebased Payment Award Equity Instruments Other than Options Nonvested Fair Value		$ 100,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value		$ 14,000	$ 273,000
Minimum [Member] | Common Stock Options [ member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Purchase Price of Common Stock, Percent		110%
Minimum [Member] | Restricted Stock Units (RSUs) [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)		3 years
The 2015 Employee Stock Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Additional Shares Authorized	1,750,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant		1,759,566
Officer and Director Share Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant		0
Common Stock, Shares, Issued (in shares)		0	0

Note 11 - Stock-Based Compens_4

Note 11 - Stock-Based Compensation - Stock Option Activity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended		228 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Options (in shares)	303	307
Options, weighted average exercise price (in dollars per share)	$ 19,360.30	$ 19,577.10
Options, weighted average remaining contractual life (Year)	4 years 7 days	5 years 7 days	5 years 11 months 12 days
Options, intrinsic value	$ 0	$ 0	$ 0
Options expired (in shares)		(4)
Options expired, weighted average exercise price (in dollars per share)		$ 36,000
Options (in shares)	303	303	307
Options, weighted average exercise price (in dollars per share)	$ 19,360.30	$ 19,360.30	$ 19,577.10
Exercisable (in shares)	303
Exercisable, weighted average exercise price (in dollars per share)	$ 19,360.30
Exercisable, weighted average remaining contractual life (Year)	4 years 7 days
Exercisable, intrinsic value	$ 0
Vested and expected to vest (in shares)	303
Vested and expected to vest, weighted average exercise price (in dollars per share)	$ 19,360.30
Vested and expected to vest, weighted average remaining contractual life (Year)	4 years 7 days
Vested and expected to vest, intrinsic value	$ 0

Note 11 - Stock-Based Compens_5

Note 11 - Stock-Based Compensation - Options Outstanding and Vested (Details) shares in Thousands	12 Months Ended
	Dec. 31, 2022 $ / shares shares
Options Outstanding (in shares) | shares	303
Weighted Average Remaining Contractual Life (Year)	4 years 7 days
Weighted Average Exercise Price (in dollars per share)	$ 19,360.30
Number Exercisable (in shares) | shares	303
Weighted Average Exercise Price, options vested (in dollars per share)	$ 19,360.30
Exercise Price Range 1 [Member]
Exercise Price, Upper Limit (in dollars per share)	$ 334
Options Outstanding (in shares) | shares	155
Weighted Average Remaining Contractual Life (Year)	5 years 5 months 8 days
Weighted Average Exercise Price (in dollars per share)	$ 334
Number Exercisable (in shares) | shares	155
Weighted Average Exercise Price, options vested (in dollars per share)	$ 334
Exercise Price Range 2 [Member]
Exercise Price, Upper Limit (in dollars per share)	$ 28,400
Options Outstanding (in shares) | shares	31
Weighted Average Remaining Contractual Life (Year)	4 years 2 months 4 days
Weighted Average Exercise Price (in dollars per share)	$ 17,323.87
Number Exercisable (in shares) | shares	31
Weighted Average Exercise Price, options vested (in dollars per share)	$ 17,323.87
Exercise Price, Lower Limit (in dollars per share)	16,400
Exercise Price Range 3 [Member]
Exercise Price, Upper Limit (in dollars per share)	$ 36,000
Options Outstanding (in shares) | shares	103
Weighted Average Remaining Contractual Life (Year)	2 years
Weighted Average Exercise Price (in dollars per share)	$ 36,000
Number Exercisable (in shares) | shares	103
Weighted Average Exercise Price, options vested (in dollars per share)	$ 36,000
Exercise Price Range 4 [Member]
Exercise Price, Upper Limit (in dollars per share)	$ 162,000
Options Outstanding (in shares) | shares	14
Weighted Average Remaining Contractual Life (Year)	2 years 10 months 6 days
Weighted Average Exercise Price (in dollars per share)	$ 112,097.14
Number Exercisable (in shares) | shares	14
Weighted Average Exercise Price, options vested (in dollars per share)	$ 112,097.14
Exercise Price, Lower Limit (in dollars per share)	$ 103,680

Note 11 - Stock-Based Compens_6

Note 11 - Stock-Based Compensation - Restricted Stock Units Award Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Awards outstanding, shares (in shares)	10,060	20,671
Awards outstanding, Weighted Average Grant Date Fair Value (in dollars per share)	$ 24.39	$ 76.03
Awards outstanding, Weighted Average Remaining Contractual Term (Year)	2 months 1 day	8 months 19 days	11 months 23 days
Awarded, shares (in shares)		4,500
Awarded, Weighted Average Grant Date Fair Value (in dollars per share)		$ 32.20
Released, shares (in shares)	(8,590)	(13,386)
Released, Weighted Average Grant Date Fair Value (in dollars per share)	$ 25.02	$ 104.31
Forfeited, shares (in shares)	(1,053)	(1,725)
Forfeited, , Weighted Average Grant Date Fair Value (in dollars per share)	$ 24.25	$ 53.62
Awards outstanding, shares (in shares)	417	10,060	20,671
Awards outstanding, Weighted Average Grant Date Fair Value (in dollars per share)	$ 11.64	$ 24.39	$ 76.03

Note 11 - Stock-based Compens_7

Note 11 - Stock-based Compensation - Noncash Stock-based Compensation Expense Related to Stock Options, ESPP, and RSUs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Allocated Share-based Compensation Expense	$ 127	$ 1,015
Cost of Sales [Member]
Allocated Share-based Compensation Expense	18	101
Research and Development Expense [Member]
Allocated Share-based Compensation Expense	37	287
Selling, General and Administrative Expenses [Member]
Allocated Share-based Compensation Expense	$ 72	$ 627

Note 12 - Income Taxes (Details

Note 12 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Expense (Benefit), Total	$ 0	$ 0
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	5,100	4,700
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	208,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards	344,300
Operating Loss Carryforwards, Not Subject to Expiration	86,800
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 4,300	$ 4,200

Note 12 - Income Taxes - Effect

Note 12 - Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Tax at federal statutory rate	$ (3,701)	$ (3,657)
State taxes, net of federal benefit	(916)	(711)
Permanent differences	(484)	(445)
Change in valuation allowance	5,084	5,104
Research credits	(273)	(286)
Nondeductible interest expense	290	0
Other	0	(5)
Provision for taxes	$ 0	$ 0

Note 12 - Income Taxes - Deferr

Note 12 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Federal, state and foreign net operating losses	$ 85,547	$ 83,211
Research and other credits	5,343	4,892
Operating lease liability	544	752
Fixed assets	471	0
Accruals and other	3,628	2,845
Capitalized research and development	1,019	0
Total deferred tax assets	96,552	91,700
Less: Valuation allowance	(95,992)	(90,908)
Total net deferred tax assets	560	792
Property and equipment	0	(2)
Operating lease right of use asset	(560)	(790)
Total deferred tax liabilities	(560)	(792)
Net deferred tax assets (liabilities)	$ 0	$ 0

Note 12 - Income Taxes - Reconc

Note 12 - Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Balance at beginning of year	$ 2,366	$ 2,307
Increase based on the tax positions in the current year	203	228
Increase (Decrease) for tax positions of prior year	12
Increase (Decrease) for tax positions of prior year		(169)
Balance at end of year	$ 2,581	$ 2,366

Note 13 - 401(k) Plan (Details

Note 13 - 401(k) Plan (Details Textual) - Pension Plan [Member] - The 401(k) Plan [Member] $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	99%
Defined Contribution Plan, Cost	$ 0

Note 14 - Subsequent Events (De

Note 14 - Subsequent Events (Details Textual) - $ / shares	Feb. 14, 2023	Jan. 18, 2023	Dec. 31, 2022	Dec. 31, 2021
Class of Warrant or Right, Outstanding			51,185,758	26,456,895
Share Price			$ 1.09
Subsequent Event [Member]
Share Price		$ 1.23
Subsequent Event [Member] | Restricted Stock [Member] | Share-Based Payment Arrangement, Employee [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Granted		1,502,928
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)		2 years
Subsequent Event [Member] | Private Pre-funded Warrants [Member]
Class of Warrant or Right, Exercised (in shares)	747,864
Stock Issued During Period, Shares, Warrants Exercised	747,864
Class of Warrant or Right, Outstanding	622,000