NeuroMetrix (NURO) 10-K 8 Feb 18 2017 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Feb. 02, 2018	Jun. 30, 2017
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Entity Registrant Name	NeuroMetrix, Inc.
Entity Central Index Key	1,289,850
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Smaller Reporting Company
Entity Public Float			$ 4,309,853
Trading Symbol	NURO
Entity Common Stock, Shares Outstanding		7,141,940

Balance Sheets

Balance Sheets - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 4,043,681	$ 3,949,135
Accounts receivable, net of allowances of $25,000 at December 31, 2017 and 2016	1,049,329	738,729
Inventories	1,369,647	1,252,238
Prepaid expenses and other current assets	2,640,717	1,646,821
Total current assets	9,103,374	7,586,923
Fixed assets, net	440,842	532,706
Other long-term assets	55,008	164,262
Total assets	9,599,224	8,283,891
Current liabilities:
Accounts payable	733,305	734,048
Accrued compensation	786,184	307,471
Accrued expenses	2,242,315	1,648,731
Deferred revenue	820,031	628,236
Total current liabilities	4,581,835	3,318,486
Common stock warrants	0	4,641
Total liabilities	4,581,835	3,323,127
Commitments and contingencies (Note 8)
Stockholders’ equity
Common stock, $0.0001 par value; 100,000,000 authorized at December 31, 2017 and 2016; 2,706,066 and 836,863 shares issued and outstanding at December 31, 2017 and 2016, respectively	271	84
Additional paid-in capital	196,355,142	183,439,463
Accumulated deficit	(191,338,054)	(178,478,801)
Total stockholders’ equity	5,017,389	4,960,764
Total liabilities and stockholders’ equity	9,599,224	8,283,891
Preferred stock
Stockholders’ equity
Preferred stock	0	0
Convertible preferred stock
Stockholders’ equity
Preferred stock	$ 30	$ 18

Balance Sheets (Parenthetical)

Balance Sheets (Parenthetical) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current	$ 25,000	$ 25,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	2,706,066	836,863
Common stock, shares outstanding (in shares)	2,706,066	836,863

Statements of Operations

Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenues	$ 17,092,336	$ 12,027,528
Cost of revenues	10,235,538	7,113,005
Gross profit	6,856,798	4,914,523
Operating expenses:
Research and development	3,497,636	4,394,353
Sales and marketing	10,751,863	10,855,445
General and administrative	5,689,917	4,872,670
Total operating expenses	19,939,416	20,122,468
Loss from operations	(13,082,618)	(15,207,945)
Interest income	14,885	19,132
Change in fair value of warrant liability	208,480	275,662
Net loss	(12,859,253)	(14,913,151)
Net loss applicable to common stockholders:
Deemed dividends attributable to preferred shareholders (Note 12)	(6,874,780)	(19,846,377)
Net loss applicable to common stockholders	$ (19,734,033)	$ (34,759,528)
Net loss per common share applicable to common stockholders, basic and diluted (in dollars per share)	$ (11.60)	$ (58.21)
Weighted average number of common shares outstanding, basic and diluted (in shares)	1,701,481	597,130

Statements of Changes in Stockh

Statements of Changes in Stockholders' Equity - USD ($)	Total	Series B – F Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Series D Preferred Stock	Series D Preferred StockSeries B – F Preferred Stock	Series D Preferred StockAdditional Paid-In Capital	Series E Preferred Stock	Series E Preferred StockSeries B – F Preferred Stock	Series E Preferred StockAdditional Paid-In Capital	Series F Preferred Stock	Series F Preferred StockSeries B – F Preferred Stock	Series F Preferred StockAdditional Paid-In Capital
Beginning Balance at Dec. 31, 2015	$ 12,562,708	$ 21	$ 51	$ 176,128,286	$ (163,565,650)
Beginning Balance (in shares) at Dec. 31, 2015		20,946	505,917
Stock-based compensation expense	225,408			225,408
Issuance of Series D preferred stock and warrants and redemption of Series C preferred stock under purchase agreement						$ 6,738,500	$ 8	$ 6,738,492
Issuance of Series D preferred stock and warrants and redemption of Series C preferred stock under purchase agreement (in shares)							7,500
Issuance of common stock upon conversion of preferred stock	0	$ (11)	$ 30	(19)
Issuance of common stock upon conversion of preferred stock (in shares)		(10,743.35)	(304,311)
Issuance of common stock under employees stock purchase plan	28,538		$ 1	28,537
Issuance of common stock under employee stock purchase plan (in shares)			4,375
Common stock issued to settle incentive compensation obligations	318,761		$ 2	318,759
Common stock issued to settle incentive compensation obligations (in shares)			22,260
Net loss	(14,913,151)				(14,913,151)
Ending Balance at Dec. 31, 2016	4,960,764	$ 18	$ 84	183,439,463	(178,478,801)
Ending Balance (in shares) at Dec. 31, 2016		17,702.65	836,863
Stock-based compensation expense	209,691			209,691
Issuance of common stock upon conversion of preferred stock	0	$ (6)	$ 184	(178)
Issuance of common stock upon conversion of preferred stock (in shares)		(5,843.67)	(1,833,240)
Issuance of common stock under employees stock purchase plan	20,768		$ 1	20,767
Issuance of common stock under employee stock purchase plan (in shares)			11,583
Issuance of preferred stock and warrants under purchase agreement									$ 6,057,389	$ 7	$ 6,057,382	$ 6,628,030	$ 11	$ 6,628,019
Issuance of preferred stock and warrants under purchase agreement (in shares)										7,000			10,621
Issuance of common stock in exchange for warrants	0		$ 2	(2)
Issuance of common stock in exchange for warrants (in shares)			24,380
Net loss	(12,859,253)				(12,859,253)
Ending Balance at Dec. 31, 2017	$ 5,017,389	$ 30	$ 271	$ 196,355,142	$ (191,338,054)
Ending Balance (in shares) at Dec. 31, 2017		29,479.98	2,706,066

Statements of Cash Flows

Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Cash flows for operating activities:
Net loss	$ (12,859,253)	$ (14,913,151)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	262,334	251,327
Stock-based compensation	209,691	225,408
Change in fair value of warrant liability	(208,480)	(275,662)
Changes in operating assets and liabilities:
Accounts receivable	(310,600)	69,096
Inventories	(117,409)	(163,154)
Prepaid expenses and other current and long-term assets	(884,642)	(754,797)
Accounts payable	(8,117)	(267,583)
Accrued expenses and compensation	1,072,297	347,176
Deferred revenue	191,795	401,064
Net cash used in operating activities	(12,652,384)	(15,080,276)
Cash flows for investing activities:
Purchases of fixed assets	(163,096)	(100,499)
Net cash used in investing activities	(163,096)	(100,499)
Cash flows from financing activities:
Net proceeds from issuance of stock and warrants, including private offerings and equity plans	12,910,026	6,667,038
Net cash provided by financing activities	12,910,026	6,667,038
Net (decrease) increase in cash and cash equivalents	94,546	(8,513,737)
Cash and cash equivalents, beginning of year	3,949,135	12,462,872
Cash and cash equivalents, end of year	4,043,681	3,949,135
Supplemental disclosure of cash flow information:
Fixed asset additions included in accounts payable	7,374	0
Change in fair value of warrant liability from repricing	244,611	0
Exchange of warrant liability for Series F Preferred Stock	40,772	0
Common stock issued to settle employee incentive compensation obligation	$ 0	$ 318,761

Description of Business and Bas

Description of Business and Basis of Presentation	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Description of Business and Basis of Presentation	Description of Business and Basis of Presentation NeuroMetrix, or the Company, is a commercial stage, innovation driven healthcare company combining bioelectrical and digital medicine to address chronic health conditions including chronic pain, sleep disorders, and diabetes. The Company’s lead product is Quell, an over-the-counter wearable therapeutic device for chronic pain. Quell is integrated into a digital health platform that helps patients optimize their therapy and decrease the impact of chronic pain on their quality of life. The Company also markets DPNCheck®, a rapid point-of-care test for diabetic neuropathy, which is the most common long-term complication of Type 2 diabetes. The Company maintains an active research effort. The company is located in Waltham, Massachusetts and was founded as a spinoff from the Harvard-MIT Division of Health Sciences and Technology in 1996. During 2017 the Company completed two equity offerings, detailed in Note 12 to the financial statements, which resulted in gross proceeds of $14.0 million and realized net proceeds of approximately $12.9 million after deducting fees and expenses. The accompanying financial statements have been prepared on a basis which assumes that the Company will continue as a going concern and which contemplates the realization of assets and satisfaction of liabilities and commitments in the normal course of business. The Company has suffered recurring losses from operations and negative cash flows from operating activities. At December 31, 2017 , the Company had an accumulated deficit of $191.3 million . The Company held cash and cash equivalents of $4.0 million as of December 31, 2017 . The Company believes that these resources, the $5.0 million received in January 2018 under the GSK Collaboration, as well as certain of the $21.5 million in contingent payments under development and commercialization milestones (Note 15), and the cash to be generated from expected product sales will be sufficient to meet its projected operating requirements into the fourth quarter of 2018 . The Company continues to face significant challenges and uncertainties and, as a result, the Company’s available capital resources may be consumed more rapidly than currently expected due to (a) decreases in sales of the Company’s products and the uncertainty of future revenues from new products; (b) changes the Company may make to the business that affect ongoing operating expenses; (c) changes the Company may make in its business strategy; (d) regulatory developments affecting the Company’s existing products; (e) changes the Company may make in its research and development spending plans; and (f) other items affecting the Company’s forecasted level of expenditures and use of cash resources. Accordingly, the Company may need to raise additional funds to support its operating and capital needs in the fourth quarter of 2018 . These factors raise substantial doubt about the Company’s ability to continue as a going concern for the one year period from the date of issuance of these financial statements. The financial statements do not include any adjustments that might result from the outcome of this uncertainty. The Company intends to obtain additional funding through achievement of milestones under the GSK Collaboration, public or private financing, collaborative arrangements with strategic partners, or through additional credit lines or other debt financing sources to increase the funds available to fund operations. However, the Company may not be able to secure such financing in a timely manner or on favorable terms, if at all. Furthermore, if the Company issues equity or debt securities to raise additional funds, its existing stockholders may experience dilution, and the new equity or debt securities may have rights, preferences and privileges senior to those of the Company’s existing stockholders. If the Company raises additional funds through collaboration, licensing or other similar arrangements, it may be necessary to relinquish valuable rights to its potential products or proprietary technologies, or grant licenses on terms that are not favorable to the Company. Without additional funds, the Company may be forced to delay, scale back or eliminate some of its sales and marketing efforts, research and development activities, or other operations and potentially delay product development in an effort to provide sufficient funds to continue its operations. If any of these events occurs, the Company’s ability to achieve its development and commercialization goals would be adversely affected.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Use of Estimates and Assumptions The preparation of financial statements in conformity with United States generally accepted accounting principles requires management to make significant estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during reporting periods. Actual results could differ from those estimates. The Company bases its estimates on historical experience and various other assumptions that it believes to be reasonable under the circumstances and regularly assesses these estimates, but actual results could differ materially from these estimates. Effects of changes in estimates are recorded in the period in which they occur. Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of ninety days or less to be cash equivalents. Cash equivalents are recorded at cost which approximates fair value. The Company invests cash primarily in a money market account and other investments which management believes are subject to minimal credit and market risk. Concentrations of Credit Risk Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents in bank deposit accounts and trade receivables. The Company invests its funds in highly rated institutions and limits its investment in any individual account so that they do not exceed FDIC limits. The Company has not experienced significant losses related to cash and cash equivalents and does not believe it is exposed to any significant credit risks relating to its cash and cash equivalents. At December 31, 2017 and 2016 , two customers accounted for 66% and 41% of accounts receivable, respectively. For the years ended December 31, 2017 and 2016 , customers accounting for more than 10% of revenue were 19% and zero of revenues, respectively. The Company relies on in-house assembly and four third-party manufacturers to manufacture the major portion of its current products and product components. The disruption or termination of the supply of these products or a significant increase in the cost of these products from these sources could have an adverse effect on the Company’s business, financial position, and results of operations. Inventories Inventories, consisting primarily of finished goods and purchased components, are stated at the lower of cost or net realizable value. Cost is determined using the first-in, first-out method. The Company writes down inventory to its net realizable value for excess or obsolete inventory. Fair Value The carrying amounts of the Company’s accounts receivable, accounts payable, and accrued expenses approximate their fair value at December 31, 2017 and 2016 due to the short-term nature of these assets and liabilities. The Company’s cash equivalents and its warrant liability are carried at fair value determined according to the fair value hierarchy described in Note 9. Revenue Recognition The Company recognizes revenue when the following criteria have been met: persuasive evidence of an arrangement exists, delivery has occurred and risk of loss has passed, the seller’s price to the buyer is fixed or determinable, and collection is reasonably assured. Revenues associated with the Company’s medical devices and consumables are generally recognized upon shipment, assuming all other revenue recognition criteria have been met. Revenue associated with shipments made to distributors who have the right to return any unsold product is recognized once the product is sold by the distributor to the end customer (i.e. under a sell-through model), assuming all other revenue recognition criteria have been met. Cash received prior to all the conditions for revenue recognition being met is recorded as deferred revenue. As of December 31, 2017 , the total value of shipments made to sell-through distributors but not yet sold through to end customers totaled $3,010,734 . Of this total, $2,190,703 was recorded as a reduction to accounts receivable and $820,031 was recorded in deferred revenue, as cash had been received. As of December 31, 2016 , the total value of shipments that had been made to sell-through distributors but have not yet been sold through to end customers totaled $1,247,545 . Of this total, $619,309 was recorded as a reduction to accounts receivable and $628,236 was recorded in deferred revenue, as cash had been received. Related costs of goods sold of $2,106,988 and $910,595 have been deferred and recorded in prepaid expenses and other current assets as of December 31, 2017 and 2016 , respectively. Revenue recognition involves judgments, including assessments of expected returns from customers who have the right to return product for any reason under 30-day or 60-day rights of return. Where the Company can reasonably estimate future returns, it recognizes revenues and records as a reduction of revenue a provision for estimated returns. The Company analyzes various factors, including its historical product returns in arriving at this judgment. Changes in judgments or estimates could materially impact the timing and amount of revenues and costs recognized. The provision for expected returns recorded as accrued expense was $666,375 and $488,200 as of December 31, 2017 and 2016 , respectively. Accounts Receivable Accounts receivable are recorded net of the allowance for doubtful accounts receivable. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in our existing accounts receivable. The Company reviews the allowance for doubtful accounts and determines the allowance based on an analysis of customer past payment history, product usage activity, and recent communications with the customer. Individual customer balances which are past due and over 90 days outstanding are reviewed individually for collectability. Account balances are written-off against the allowance when the Company feels it is probable the receivable will not be recovered. The Company does not have any off-balance sheet credit exposure related to our customers. Income Taxes The Company records income taxes using the asset and liability method. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases, and operating loss and tax credit carryforwards. The Company’s financial statements contain certain deferred tax assets, which have arisen primarily as a result of operating losses, as well as other temporary differences between financial and tax accounting. In accordance with the provisions of the Income Taxes topic of the Codification, the Company is required to establish a valuation allowance if the likelihood of realization of the deferred tax assets is reduced based on an evaluation of objective verifiable evidence. Significant management judgment is required in determining the Company’s provision for income taxes, the Company’s deferred tax assets and liabilities and any valuation allowance recorded against those net deferred tax assets. The Company evaluates the weight of all available evidence to determine whether it is more likely than not that some portion or all of the net deferred income tax assets will not be realized. Utilization of the NOL and research and development credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that have occurred previously or that could occur in the future, as provided by Section 382 of the Internal Revenue Code of 1986, as well as similar state provisions. Ownership changes may limit the amount of NOL and tax credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50 percentage points over a three-year period. If the Company has experienced a change of control, utilization of its NOL or tax credits carryforwards would be subject to an annual limitation under Section 382. Any limitation may result in expiration of a portion of the NOL or research and development credit carryforwards before utilization. Subsequent ownership changes could further impact the limitation in future years. Further, until a study is completed and any limitation known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s NOL carryforwards and research and development credit carryforwards and, if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the balance sheet or statement of operations if an adjustment were required. Management performed a two-step evaluation of all tax positions, ensuring that these tax return positions meet the “more likely than not” recognition threshold and can be measured with sufficient precision to determine the benefit recognized in the financial statements. These evaluations provide management with a comprehensive model for how a company should recognize, measure, present, and disclose in its financial statements certain tax positions that the Company has taken or expects to take on income tax returns. Research and Development Costs incurred in research and development are expensed as incurred. Included in research and development costs are wages, benefits, product design consulting, and other operating costs such as facilities, supplies, and overhead directly related to the Company’s research and development efforts. Product Warranty Costs The Company accrues estimated product warranty costs at the time of sale which are included in cost of sales in the statements of operations. The amount of the accrued warranty liability is based on historical information such as past experience, product failure rates, number of units repaired, and estimated cost of material and labor. The liabilities for product warranty costs of $127,361 and $45,879 at December 31, 2017 and 2016 , respectively, are included in accrued expenses in the accompanying balance sheets. Fixed Assets and Long-Lived Assets Fixed assets are recorded at cost and depreciated using the straight-line method over the estimated useful life of each asset. Expenditures for repairs and maintenance are charged to expense as incurred. On disposal, the related assets and accumulated depreciation are eliminated from the accounts and any resulting gain or loss is included in the Company’s statement of operations. Leasehold improvements are amortized over the shorter of the estimated useful life of the improvement or the remaining term of the lease. The Company periodically evaluates the recoverability of its fixed assets and other long-lived assets whenever events or changes in circumstances indicate that an event of impairment may have occurred. This periodic review may result in an adjustment of estimated depreciable lives or asset impairment. When indicators of impairment are present, the carrying values of the asset are evaluated in relation to the assets operating performance and future undiscounted cash flows of the underlying assets. If the future undiscounted cash flows are less than their book value, an impairment may exist. The impairment is measured as the difference between the book value and the fair value of the underlying asset. Fair values are based on estimates of the market prices and assumptions concerning the amount and timing of estimated future cash flows and assumed discount rates, reflecting varying degrees of perceived risk. Accounting for Stock-Based Compensation Stock-based compensation cost is generally recognized ratably over the requisite service period. The Company uses the Black-Scholes option pricing model for determining the fair value of its stock options and amortizes its stock-based compensation expense using the straight-line method. The Black-Scholes model requires certain assumptions that involve judgment. Such assumptions are the expected share price volatility, expected life of options, expected annual dividend yield, and risk-free interest rate (See Note 3 — Stock-Based Compensation and Stockholders’ Equity). Net Loss per Common Share Basic net loss per common share is computed by dividing net loss applicable to common stockholders by the weighted average number of common shares outstanding during the period. Unvested restricted shares, although legally issued and outstanding, are not considered outstanding for purposes of calculating basic net loss per common share. Diluted net loss per common share is computed by dividing net loss by the weighted average number of common shares outstanding during the period plus the dilutive effect of the weighted average number of outstanding instruments such as options, warrants, restricted stock, and preferred stock. Because the Company has reported a net loss for all periods presented, diluted loss per common share is the same as basic loss per common share, as the effect of utilizing the fully diluted share count would have reduced the net loss per common share. Therefore, in calculating net loss per share amounts, shares underlying the following potentially dilutive weighted average number of common stock equivalents were excluded from the calculation of diluted net loss per common share because their effect was anti-dilutive for each of the periods presented: Years Ended December 31, 2017 2016 Options 99,344 52,725 Warrants 2,742,266 2,848,791 Convertible preferred stock 5,961,679 1,075,379 Total 8,803,289 3,976,895 Advertising and Promotional Costs Advertising and promotional costs are expensed as incurred. Advertising and promotion expense were approximately $6,851,000 and $6,311,000 , in 2017 and 2016 , respectively. Accumulated Other Comprehensive Items For 2017 and 2016 , the Company had no components of other comprehensive income or loss other than net loss. Segments The Company operates in one segment for the sale of medical equipment and consumables. Substantially all of the Company’s assets, revenues, and expenses for 2017 and 2016 , were located at or derived from operations in the United States. Revenues from sales outside the United States accounted for approximately 7% and 12% of total revenues in 2017 and 2016 , respectively. Risks and Uncertainties The Company is subject to risks common to companies in the medical device industry, including, but not limited to, development by the Company or its competitors of new technological innovations, dependence on key personnel, customers’ reimbursement from third-party payers, protection of proprietary technology, and compliance with regulations of the FDA and other governmental agencies. Recently Issued or Adopted Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update No. 2016-2, Leases (Topic 842) (“ASU 2016-2”). ASU 2016-2 requires that lessees will need to recognize virtually all of their leases on the balance sheet, by recording a right-of-use asset and lease liability. The provisions of this guidance are effective for annual periods beginning after December 31, 2018, and for interim periods therein. The Company is in the process of evaluating the new standard and assessing the impact, if any, ASU 2016-2 will have on the Company’s Financial Statements. In May 2014, the FASB and the International Accounting Standards Board (“IASB”) jointly issued Accounting Standards Update (“ASU”) No. 2014-9, Revenue from Contracts with Customers (“ASU 2014-9”), a comprehensive new revenue recognition standard that will supersede nearly all existing revenue recognition guidance. The objective of ASU 2014-9 is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. While the Company is still in the process of completing its evaluation of the standard, it believes the most significant impact will be related to the timing of recognition of sales to certain consumer retail distributors. Upon adoption of ASU 2014-09, the Company will no longer be permitted to defer revenue under the sell-through model, but rather, will be required to estimate the effects of returns and allowances provided to distributors and record revenue at the time of sale to the distributor resulting in earlier recognition of revenues. The Company expects to adopt ASU 2014-09, using the full retrospective method, upon its effective date of January 1, 2018. The Company anticipates the impact of adoption will be a credit to accumulated deficit of approximately $0.3 million as of January 1, 2018.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Stock-Based Compensation	Stock-Based Compensation During 2004, the Company adopted the 2004 Stock Option and Incentive Plan, as amended and restated most recently in 2016. At the Annual Meeting of Stockholders held on May 2, 2017 , the stockholders of the Company approved the Company’s Ninth Amended and Restated 2004 Stock Option and Incentive Plan (the “2004 Stock Plan”), which, among other things, increased the number of shares of the Company’s common stock authorized for issuance thereunder by 600,000 shares. The 2004 Stock Plan, among other things, provides for granting of incentive and nonqualified stock option and stock bonus awards to officers, employees and outside consultants. Outstanding options under the 2004 Stock Plan generally vest over three or four years and terminate 10 years after the grant date, or earlier if the option holder is no longer an executive officer, employee, consultant, advisor or director, as applicable, of the Company. As of December 31, 2017 , 728,946 shares of common stock were authorized for issuance under the 2004 Stock Plan, of which 30,162 shares had been issued, 80,537 shares were subject to outstanding options at a weighted average exercise price of $19.32 per share and 618,247 shares were available for future grant. During May 2009, the Company adopted the 2009 Non-Qualified Inducement Stock Plan (the “2009 Inducement Plan”). The 2009 Inducement Plan is intended to encourage and enable employees, including prospective employees, of the Company upon whose judgment, initiative, and efforts the Company largely depends for the successful conduct of its business to acquire a proprietary interest in the Company. The 2009 Inducement Plan, among other things, provides for the granting of awards, including non-qualified stock options, restricted stock, and unrestricted stock. As of December 31, 2017 , 12,500 shares of common stock were authorized for issuance and were available for future grant under the 2009 Inducement Plan. The exercise price of stock options awarded under the 2004 Stock Plan and the 2009 Inducement Plan may not be less than the fair value of the common stock on the date of the option grant. For holders of more than 10% of the Company’s total combined voting power of all classes of stock, incentive stock options may not be granted at less than 110% of the fair value of the Company’s common stock at the date of grant and for a term not to exceed five years. In June 2004, the Company adopted the 2004 Employee Stock Purchase Plan (the “2004 ESPP”). All of the Company’s employees who had been employed by the Company for at least 60 days and whose customary employment is for more than 20 hours per week and for more than five months in any calendar year were eligible to participate and any employee who owned 5% or more of the voting power or value of the Company’s stock was not eligible to participate. The 2004 ESPP authorized the issuance of up to a total of 326 shares of the Company’s common stock to participating employees. In May 2010, the Company adopted the 2010 Employee Stock Purchase Plan (the “2010 ESPP”). The 2010 ESPP initially authorized the issuance of up to a total of 217 shares, of the Company’s common stock to participating employees plus an annual increase on the first day of each of the Company’s fiscal years beginning in 2011, equal to the lesser of (i) 521 shares, (ii) 1 percent of the shares of common stock outstanding on the last day of the immediately preceding fiscal year, or (iii) such lesser number of shares as is determined by the Board. All of the Company’s full-time employees and certain part-time employees are eligible to participate in the Amended and Restated 2010 ESPP. For part-time employees to be eligible, they must have customary employment of more than five months in any calendar year and more than 20 hours per week. Employees who, after exercising their rights to purchase shares under the Amended and Restated 2010 ESPP, would own shares representing 5% or more of the voting power of the Company’s common stock, are ineligible to participate. Under the Amended and Restated 2010 ESPP, participating employees can authorize the Company to withhold up to 10% of their earnings during consecutive six-month payment periods for the purchase of the shares. At the conclusion of each period, participating employees can purchase shares at 85% of the lower of their fair value at the beginning or end of the period. The Amended and Restated 2010 ESPP is regarded as a compensatory plan. For the years ended December 31, 2017 and 2016 the Company issued 11,583 and 4,375 shares of its common stock, respectively, under the Amended and Restated 2010 ESPP. As of December 31, 2017 , there were 58 remaining shares to be issued under the Amended and Restated 2010 ESPP. The Company uses the Black-Scholes option pricing model for determining the fair value of shares of common stock issued or to be issued under the 2010 ESPP and the Amended and Restated 2010 ESPP. The following assumptions are used in determining fair value: The risk-free interest rate assumption is based on the United States Treasury’s constant maturity rate for a six month term (corresponding to the expected option term) on the date the option was granted. The expected dividend yield is zero because the Company does not currently pay dividends nor expects to do so during the expected option term. An expected term of six months is used based on the duration of each plan offering period. The volatility assumption is based on a consideration of stock price volatility over the most recent period of time corresponding to the expected term and is also based on expected future stock price volatility. The weighted average grant-date fair value of stock options used in the calculation of stock-based compensation expense in the accompanying statement of operations for the years ended December 31, 2017 and 2016 is calculated using the following assumptions: Years Ended December 31, 2017 2016 Risk-free interest rate 1.8- 2.1% 0.9- 1.8% Expected dividend yield — — Expected option term 5 years 5 years Volatility 70.0 % 70.0 % The risk-free interest rate assumption is based on the United States Treasury’s constant maturity rate for a five year term (corresponding to the expected option term) on the date the option was granted. The expected dividend yield is zero as the Company does not currently pay dividends nor expects to do so during the expected option term. The expected option term of five years is estimated based on an analysis of actual option exercises. The volatility assumption is based on daily historical volatility during the time period that corresponds to the expected option term and expected future stock price volatility. The pre-vesting forfeiture rate is based on the historical and projected average turnover rate of employees. A summary of option activity for the year ended December 31, 2017 is presented below: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in years) Aggregate Intrinsic Value Outstanding at December 31, 2016 97,891 $ 37.95 Granted 6,488 2.37 Exercised — — Forfeited (23,825 ) 83.27 Expired (17 ) 11,187.28 Outstanding at December 31, 2017 80,537 19.32 8.6 $ — Vested or expected to vest at December 31, 2017 80,537 19.32 8.6 — Exercisable at December 31, 2017 25,388 37.26 8.3 — Expected to vest options are determined by applying the pre-vesting forfeiture rate to the total outstanding options. Aggregate intrinsic value represents the total pre-tax intrinsic value (the aggregate difference between the closing stock price of the Company’s common stock as of December 31, 2017 , as applicable, and the exercise price for the in-the-money options) that would have been received by the option holders if all the in-the-money options had been exercised on December 31, 2017 . The weighted average per share grant-date fair values of options granted during 2017 and 2016 was $2.37 and $6.80 , respectively. The aggregate intrinsic value of options issued or exercised during 2017 and 2016 was $0 . Total unrecognized stock-based compensation costs related to non-vested stock options was $335,405 , which related to 80,537 shares with a per share weighted fair value of $19.32 as of December 31, 2017 . This unrecognized cost is expected to be recognized over a weighted average period of approximately 2.6 years . Cash received from option exercises and purchases under the 2004 ESPP and the 2010 ESPP for 2017 and 2016 , was $20,768 and $28,538 , respectively. The Company issues new shares upon option exercises, purchases under the Company’s ESPPs, and vesting of restricted stock. The Company recorded stock-based compensation expense of $209,691 and $225,408 for 2017 and 2016 , respectively.

Inventories

Inventories	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventories	Inventories Inventories consist of the following: December 31, 2017 2016 Purchased components $ 505,293 $ 466,906 Work in progress — 154,971 Finished goods 864,354 630,361 $ 1,369,647 $ 1,252,238

Fixed Assets

Fixed Assets	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Fixed Assets	Fixed Assets Fixed assets consist of the following: Estimated Useful Life (Years) December 31, 2017 2016 Computer and laboratory equipment 3 $ 881,969 $ 1,724,819 Furniture and equipment 3 227,845 319,046 Production equipment 7 346,469 938,357 Leasehold improvements * 117,994 117,994 1,574,277 3,100,216 Less – accumulated depreciation (1,133,435 ) (2,567,510 ) $ 440,842 $ 532,706 * Lesser of life of lease or estimated useful life. Depreciation expense was $262,334 and $251,327 for 2017 and 2016 , respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued Expenses	Accrued Expenses Accrued expenses consist of the following for the years ended December 31, 2017 and 2016 : December 31, 2017 2016 Sales return allowance $ 666,375 $ 488,200 Professional services 603,000 390,800 Technology fees 450,000 450,000 Advertising 160,800 28,100 Warranty 127,361 45,879 Other 234,779 245,752 $ 2,242,315 $ 1,648,731

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes Current income tax expense (benefit) attributable to continuing operations was zero for the years ended December 31, 2017 and 2016 . The Company’s effective income tax rate differs from the statutory federal income tax rate as follows for the years ended December 31, 2017 and 2016 . Years Ended December 31, 2017 2016 Federal tax provision (benefit) rate (34.0 )% (34.0 )% State tax provision, net of federal provision (5.9 ) (4.2 ) Permanent items (0.1 ) (0.2 ) Federal research and development credits (0.7 ) (0.9 ) Change in statutory tax rate 150.3 — Valuation allowance (109.6 ) 39.3 Effective income tax rate — — The Company’s deferred tax assets consist of the following: December 31, 2017 2016 Deferred tax assets: Net operating loss carryforwards $ 31,902,006 $ 45,759,780 Research and development credit carryforwards 2,432,058 2,180,700 Accrued expenses 748,334 752,866 Stock-based compensation 229,676 566,487 Other 19,240 14,321 Total gross deferred tax assets 35,331,314 49,274,154 Valuation allowance (35,331,314 ) (49,274,154 ) Net deferred tax assets $ — $ — At December 31, 2017 , the Company has federal and state net operating loss carryforwards (“NOL”) of $145.2 million and $51.6 million , respectively, as well as federal and state tax credits of $1.5 million and $1.1 million , respectively, which may be available to reduce future taxable income and the related taxes thereon. This amount includes tax benefits of $2.6 million and $71,238 attributable to NOL and tax credit carryforwards, respectively, that result from the exercise of employee stock options. The tax benefit of these items will be recorded as a credit to additional paid-in capital upon realization of the deferred tax asset or reduction in income taxes payable. The federal NOLs begin to expire in 2019 and the state NOLs begin to expire in 2018 . The federal and state research and development credits both begin to expire in 2018 . In accordance with the provisions of the Income Taxes topic of the Codification, the Company has evaluated the positive and negative evidence bearing upon the realizability of its deferred tax assets, which are comprised principally of net operating losses. Management has determined that it is more likely than not that the Company will not recognize the benefits of federal and state deferred tax assets and, as a result, a valuation allowance of approximately and $35.3 million and $49.3 million has been established at December 31, 2017 and 2016 , respectively. In 2017, the valuation allowance decreased primarily due to the impact of the change in statutory rates on the Company’s net operating losses. Utilization of the NOL and research and development credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that have occurred previously or that could occur in the future, as provided by Section 382 of the Internal Revenue Code of 1986, as well as similar state provisions. Ownership changes may limit the amount of NOL and tax credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50 percentage points over a three-year period. If the Company has experienced a change of control, utilization of its NOL or tax credits carryforwards would be subject to an annual limitation under Section 382. Any limitation may result in expiration of a portion of the NOL or research and development credit carryforwards before utilization. Subsequent ownership changes could further impact the limitation in future years. Further, until a study is completed and any limitation known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s NOL carryforwards and research and development credit carryforwards and, if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the balance sheet or statement of operations if an adjustment were required. The Company has not recorded any amounts for unrecognized tax benefits as of December 31, 2017 or 2016 . The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. There are currently no pending income tax examinations. The Company’s tax years are still open under statute from December 31, 2014 to the present. Earlier years may be examined to the extent that tax credit or net operating loss carryforwards are used in future periods. The Company’s policy is to record interest and penalties related to income taxes as part of its income tax provision.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases In August 2014, the Company entered into a 5 -year operating lease agreement with one 5 -year extension option for manufacturing and order fulfillment facilities in Woburn, Massachusetts (the “Woburn Lease”). The Woburn Lease commenced December 15, 2014 and has a monthly base rent of $7,815 . In September 2014, the Company entered into a 7 -year operating lease agreement with one 5 -year extension option for its corporate office and product development activities in Waltham, Massachusetts (the “Waltham Lease”). The term of the Waltham Lease commenced on February 20, 2015 and includes fixed payment obligations that escalate over the initial lease term. Average monthly base rent under the 7 -year lease is approximately $37,788 . These payment obligations will be accrued and recognized over the term of occupancy such that rent expense is recognized on a straight-line basis. Under the Waltham Lease, the landlord was responsible for making certain improvements to the leased space at an agreed upon cost to the landlord. The landlord and the Company mutually agreed to make improvements in excess of the agreed upon landlord cost, and the landlord billed that excess cost to the Company as additional rent. This additional rent of $275,961 was included in the net calculation of lease payments, so that rent expense is recognized on a straight-line basis over the remaining term of occupancy. Future minimum lease payments under non-cancellable operating leases as of December 31, 2017 are as follows: 2018 573,421 2019 549,403 2020 475,408 2021 487,379 2022 81,562 Total minimum lease payments $ 2,167,173 Total recorded rent expense was $670,860 and $581,928 , for 2017 and 2016 , respectively. The Company records rent expense on its facility lease on a straight-line basis over the lease term. Other Commitments At December 31, 2017 , other commitments, comprised of purchase orders, totaled approximately $4,218,229 .

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Fair Value Measurements and Disclosures Topic of the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (the “Codification”) defines fair value, establishes a framework for measuring fair value in applying generally accepted accounting principles, and expands disclosures about fair value measurements. This Codification topic identifies two kinds of inputs that are used to determine the fair value of assets and liabilities: observable and unobservable. Observable inputs are based on market data or independent sources while unobservable inputs are based on the Company’s own market assumptions. Once inputs have been characterized, this Codification topic requires companies to prioritize the inputs used to measure fair value into one of three broad levels. Fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities. Fair values identified by Level 2 inputs utilize observable inputs other than Level 1 prices, 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 related assets or liabilities. Fair values identified by Level 3 inputs are unobservable data points and are used to measure fair value to the extent that observable inputs are not available. Unobservable inputs reflect the Company’s own assumptions about the assumptions that market participants would use at pricing the asset or liability. The following tables present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis for the periods presented and indicates the fair value hierarchy of the valuation techniques it utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities. Fair values determined by Level 2 inputs utilize data points that are observable such as quoted prices, interest rates, and yield curves. Fair values determined by Level 3 inputs are unobservable data points for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. December 31, 2017 Fair Value Measurements at December 31, 2017 Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 1,744,965 $ 1,744,965 $ — $ — Total $ 1,744,965 $ 1,744,965 $ — $ — The following table provides a summary of changes in the fair value of the Company’s Level 3 financial liabilities between December 31, 2015 and December 31, 2017 . 2014 Offering 2013 Offering Total Balance at December 31, 2015 $ 227,992 $ 52,311 $ 280,303 Change in fair value of warrant liability (223,880 ) (51,782 ) (275,662 ) Balance at December 31, 2016 $ 4,112 $ 529 $ 4,641 Change in fair value of warrant liability from repricing (see Note 12) 177,999 66,612 244,611 Change in fair value of warrant liability (147,278 ) (61,202 ) (208,480 ) Repurchase and retirement of warrants (see Note 12) (34,833 ) (5,939 ) (40,772 ) Balance at December 31, 2017 $ — $ — $ — December 31, 2016 Fair Value Measurements at December 31, 2016 Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 833,831 $ 833,831 $ — $ — Total $ 833,831 $ 833,831 $ — $ — Liabilities: Common stock warrants $ 4,641 $ — $ — $ 4,641 Total $ 4,641 $ — $ — $ 4,641 Due to the lack of market quotes relating to our common stock warrants, the fair value of the common stock warrants was determined at December 31, 2016 using the Black-Scholes model, which is based on Level 3 inputs. As of December 31, 2016 , inputs used in the Black-Scholes model are presented below. The assumptions used may change as the underlying sources of these assumptions and market conditions change. Based on the Black-Scholes model, the Company recorded a common stock warrants liability of $4,641 at December 31, 2016 . Black-Scholes Inputs to Warrant Liability Valuation at December 31, 2016 Stock Price Exercise Price Expected Volatility Risk-Free Interest Expected Term Dividends Warrants: 2014 Offering $ 5.92 $ 65.28 64.19 % 1.33 % 2 years, 6 months none 2013 Offering $ 5.92 $ 64.00 71.61 % 0.99 % 1 year, 5 months none

Retirement Plan

Retirement Plan	12 Months Ended
	Dec. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Retirement Plan	Retirement Plan The Company has established a 401(k) defined contribution savings plan for its employees who meet certain service period and age requirements. Contributions are permitted up to the maximum allowed under the Internal Revenue Code of each covered employee’s salary. The savings plan permits the Company to contribute at its discretion. In 2017 and 2016 the Company made no contributions to the plan.

Credit Facility

Credit Facility	12 Months Ended
	Dec. 31, 2017
Debt Disclosure [Abstract]
Credit Facility	Credit Facility The Company is party to a Loan and Security Agreement, or the Credit Facility, with a bank. As of December 31, 2017 , the Credit Facility permitted the Company to borrow up to $2.5 million on a revolving basis. The Credit Facility was subsequently amended, most recently on January 17, 2018 and extended until January 15, 2019 . Amounts borrowed under the Credit Facility will bear interest equal to the prime rate plus 0.5% . Any borrowings under the Credit Facility will be collateralized by the Company’s cash, accounts receivable, inventory, and equipment. The Credit Facility also includes traditional lending and reporting covenants. These include certain financial covenants applicable to liquidity that are to be maintained by the Company. As of December 31, 2017 , the Company was in compliance with these covenants and had not borrowed any funds under the Credit Facility. However, $0.2 million of the amount under the Credit Facility is restricted to support letters of credit issued in favor of our facilities landlords. Consequently, the amount available for borrowing under the Credit Facility as of December 31, 2017 was approximately $2.3 million .

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Preferred stock and convertible preferred stock consist of the following: December 31, 2017 2016 Preferred stock, $0.001 par value; 5,000,000 shares authorized at December 31, 2017 and 2016; no shares issued and outstanding at December 31, 2017 and 2016 $ — $ — Series B convertible preferred stock, $0.001 par value, 147,000 shares designated at December 31, 2017 and 2016, and 500 shares issued and outstanding at December 31, 2017 and 2016 1 1 Series D convertible preferred stock, $0.001 par value, 21,300 and zero shares designated at December 31, 2017 and 2016, respectively, 14,052.93 and 17,202.65 shares issued and outstanding at December 31, 2017 and 2016, respectively 14 17 Series E convertible preferred stock, $0.001 par value, 7,000 and zero shares designated at December 31, 2017 and 2016, respectively, and 7,000 and zero shares issued and outstanding at December 31, 2017 and 2016, respectively 7 — Series F convertible preferred stock, $0.001 par value, 10,621 and zero shares designated at December 31, 2017 and 2016, respectively, and 7,927.05 and zero shares issued and outstanding at December 31, 2017 and 2016, respectively 8 — Private and Public Offerings of Common Stock and Warrants 2017 activity In 2017, the Company entered into agreements with respect to a private equity offering (the “Q3 2017 Offering”) with an institutional investor and its affiliates (collectively the “Investor”). In the Q3 2017 Offering, the Company issued 7,000 shares of Series F convertible preferred stock (the “Series F Preferred Stock”) at a price of $1,000 per share. The Q3 2017 Offering also reset the conversion price of 14,052.93 shares of Series D convertible preferred stock and 7,000 shares of Series E convertible preferred stock that were held by the Investor to $2.63 per share. The Q3 2017 Offering resulted in gross proceeds of $7.0 million , and after deducting fees and expenses, net proceeds were $6.6 million . In the third quarter of 2017, the Company also entered into an exchange agreement pursuant to which it issued the Investor 3,621 shares of Series F Preferred Stock in exchange for the repurchase and retirement of 4,184,483 warrants to purchase common stock valued by an independent party at $3,622,219 . Also in 2017, the Company completed a private equity offering (the “Q1 2017 Offering”) with the Investor and issued (i) 7,000 shares of Series E convertible preferred stock (the “Series E Preferred Stock”) at a price of $1,000 per share, and (ii) warrants to purchase up to 1,250,000 shares of common stock, par value $0.0001 per share (the “Common Stock”), at an exercise price of $5.60 per share. As a part of this offering, the Company reset (i) the conversion price of 19,458.90 shares of Series D convertible preferred stock that were held by the Investor to $5.60 per share, and (ii) the exercise price of warrants to purchase up to 2,934,484 shares of Common Stock that were held by the Investor to $5.60 per share. The Q1 2017 Offering resulted in gross proceeds of 7.0 million , and after deducting fees and expenses, net proceeds were $6.3 million . Each share of Series D Preferred Stock, Series E Preferred Stock, and Series F Preferred Stock (collectively the "Preferred Stock") have a stated value of $1,000 and is convertible at the option of the holder into the number of shares of Common Stock determined by dividing the stated value by the conversion price of $2.63 , which is subject to adjustment as provided in the Certificate of Designation for the Preferred Stock. The Preferred Stock has no dividend rights, liquidation preference or other preferences over Common Stock and has no voting rights except as provided in the Certificate of Designation for the Preferred Stock and as required by law. The Q3 2017 Offering and the Q1 2017 Offering were accounted for as extinguishments of the Investor’s equity holdings in recognition of the revisions of certain preexisting equity instruments and the significant transfer of value in excess of the funding received by the Company. Under the extinguishment model, a deemed dividend was recognized within additional paid in capital which represented the fair value of issued Preferred Stock plus the incremental fair value of repricing the Preferred Stock held by the Investor, less the fair value of the consideration transferred, less the carrying value of the outstanding Preferred Stock, and warrants to purchase Common Stock. The amount of the deemed dividend totaled $2.8 million and $4.0 million for the Q3 2017 Offering and the Q1 2017 Offering, respectively. The Company determined that equity classification was appropriate for the warrants issued in the Q1 2017 Offering, following guidance in the Derivatives and Hedging topic of the Codification. In making this equity classification determination, the Company noted the warrants may only be settled in shares of common stock and had no requirements to be settled in registered shares when exercised. The fair value of the five year warrants was estimated to be $3.5 million on the offering date using a Black-Scholes model with the following assumptions: stock price of $4.96 , exercise price of $5.60 , expected volatility of 70.2% , risk free interest rate of 2.04% , expected term of five years , and no dividends. During 2017 , 3,149.72 shares of the Series D Preferred Stock were converted into a total of 859,077 shares of common stock. As of December 31, 2017 , 14,052.93 shares of Series D Preferred Stock remained outstanding. During 2017 , 2,693.95 shares of the Series F Preferred Stock were converted into a total of 974,163 shares of common stock. As of December 31, 2017 , 7,927.05 shares of Series F Preferred Stock remained outstanding. 2016 activity In June 2016, the Company completed a private equity offering with one institutional investor (the “Investor”) and issued (i) 21,300 shares of Series D convertible preferred stock (the “Series D Preferred Stock”) at a price of $1,000 per share, and (ii) warrants to purchase up to 1,475,069 shares of common stock, par value $0.0001 per share (the “Common Stock”), at an exercise price of $13.52 per share (the “June 2016 Offering”). As a part of this offering, the Company redeemed 13,800 shares of Series C convertible preferred stock (the “Series C Preferred Stock”) issued in the December 2015 Offering that were held by the Investor. Accordingly, the June 2016 Offering resulted in gross proceeds of $7.5 million , and after deducting fees and expenses, net proceeds were $6.7 million . Each share of Series D Preferred Stock had a stated value of $1,000 and is convertible at the option of the holder into the number of shares of common stock determined by dividing the stated value by the conversion price of $14.44 , which is subject to adjustment as provided in the Certificate of Designation for the Series D Preferred Stock. The Series D Preferred Stock has no dividend rights, liquidation preference or other preferences over common stock and has no voting rights except as provided in the Certificate of Designation for the Series D Preferred Stock and as required by law. The June 2016 Offering was accounted for as a modification of the Investor’s Series C Preferred Stock. Under the modification model, a deemed dividend was recognized within retained earnings which represented the fair value of consideration transferred plus the fair value of repurchased Series C Preferred Stock, less the fair value of the newly issued Series D Preferred Stock and warrants. The amount of the deemed dividend totaled $19.8 million . The Company determined that equity classification was appropriate for the warrants in the June 2016, following guidance in the Derivatives and Hedging topic of the Codification. In making this equity classification determination, the Company noted the warrants had no requirements to be settled in registered shares when exercised. The fair value of the 5 year warrants issued in connection with the June 2016 Offering was estimated to be $14.6 million on the offering date using date using a Black-Scholes model with the following assumptions: stock price of $15.92 , exercise price of $13.52 , expected volatility of 71.50% , risk free interest rate of 1.23% , expected term of five years , and no dividends. During 2016 , 4,097.35 shares of the Series D Preferred Stock were converted into a total of 283,750 shares of common stock and 6,646 shares of the Series B Preferred Stock were converted into a total of 20,561 shares of common stock. Other equity activity In 2017, the Company issued 24,380 shares of fully vested common stock in exchange for 201,327 equity-classified warrants. The fair value of the warrants was estimated to be $45,102 on the exchange date using date using a Black-Scholes model with the following assumptions: stock price of $1.85 , exercise price of $15.19 , expected volatility of 70.0% , risk free interest rate of 2.0% , expected term of 3.8 years, and no dividends. In 2016 , the Company issued shares of fully vested common stock in partial settlement of management incentive compensation. The 2016 issuance totaled 22,260 shares with a value of $318,761 reflecting the $14.32 closing price of the Company’s common stock as reported on the Nasdaq Capital Market on March 9, 2016. As of December 31, 2017 , the Company had 100,000,000 shares of common stock authorized and 2,706,066 shares issued and outstanding. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are not entitled to receive dividends unless declared by the Board of Directors. At December 31, 2017 , the Company has reserved authorized shares of common stock for future issuance as follows: Warrants 459,375 Outstanding stock options 80,537 Possible future issuance under inducement plan 12,500 Possible future issuance under stock option plans 618,247 Possible future issuance under employee stock purchase plan 58 Total 1,170,717 Reverse Stock Split On May 11, 2017, the Company effected a 1-for-8 reverse stock split of its Common Stock, or the Reverse Stock Split. The par value and other terms of the common stock were not affected by the Reverse Stock Split. The Company’s shares outstanding immediately prior to the split totaled 10,147,721 , which were subsequently adjusted to 1,268,440 shares outstanding. Share, per share, and stock option amounts for all periods presented within the financial statements contained in the Annual Report on Form 10-K have been retroactively adjusted to reflect the Reverse Stock Split.

Reverse Stock Split

Reverse Stock Split	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Reverse Stock Split	Stockholders’ Equity Preferred stock and convertible preferred stock consist of the following: December 31, 2017 2016 Preferred stock, $0.001 par value; 5,000,000 shares authorized at December 31, 2017 and 2016; no shares issued and outstanding at December 31, 2017 and 2016 $ — $ — Series B convertible preferred stock, $0.001 par value, 147,000 shares designated at December 31, 2017 and 2016, and 500 shares issued and outstanding at December 31, 2017 and 2016 1 1 Series D convertible preferred stock, $0.001 par value, 21,300 and zero shares designated at December 31, 2017 and 2016, respectively, 14,052.93 and 17,202.65 shares issued and outstanding at December 31, 2017 and 2016, respectively 14 17 Series E convertible preferred stock, $0.001 par value, 7,000 and zero shares designated at December 31, 2017 and 2016, respectively, and 7,000 and zero shares issued and outstanding at December 31, 2017 and 2016, respectively 7 — Series F convertible preferred stock, $0.001 par value, 10,621 and zero shares designated at December 31, 2017 and 2016, respectively, and 7,927.05 and zero shares issued and outstanding at December 31, 2017 and 2016, respectively 8 — Private and Public Offerings of Common Stock and Warrants 2017 activity In 2017, the Company entered into agreements with respect to a private equity offering (the “Q3 2017 Offering”) with an institutional investor and its affiliates (collectively the “Investor”). In the Q3 2017 Offering, the Company issued 7,000 shares of Series F convertible preferred stock (the “Series F Preferred Stock”) at a price of $1,000 per share. The Q3 2017 Offering also reset the conversion price of 14,052.93 shares of Series D convertible preferred stock and 7,000 shares of Series E convertible preferred stock that were held by the Investor to $2.63 per share. The Q3 2017 Offering resulted in gross proceeds of $7.0 million , and after deducting fees and expenses, net proceeds were $6.6 million . In the third quarter of 2017, the Company also entered into an exchange agreement pursuant to which it issued the Investor 3,621 shares of Series F Preferred Stock in exchange for the repurchase and retirement of 4,184,483 warrants to purchase common stock valued by an independent party at $3,622,219 . Also in 2017, the Company completed a private equity offering (the “Q1 2017 Offering”) with the Investor and issued (i) 7,000 shares of Series E convertible preferred stock (the “Series E Preferred Stock”) at a price of $1,000 per share, and (ii) warrants to purchase up to 1,250,000 shares of common stock, par value $0.0001 per share (the “Common Stock”), at an exercise price of $5.60 per share. As a part of this offering, the Company reset (i) the conversion price of 19,458.90 shares of Series D convertible preferred stock that were held by the Investor to $5.60 per share, and (ii) the exercise price of warrants to purchase up to 2,934,484 shares of Common Stock that were held by the Investor to $5.60 per share. The Q1 2017 Offering resulted in gross proceeds of 7.0 million , and after deducting fees and expenses, net proceeds were $6.3 million . Each share of Series D Preferred Stock, Series E Preferred Stock, and Series F Preferred Stock (collectively the "Preferred Stock") have a stated value of $1,000 and is convertible at the option of the holder into the number of shares of Common Stock determined by dividing the stated value by the conversion price of $2.63 , which is subject to adjustment as provided in the Certificate of Designation for the Preferred Stock. The Preferred Stock has no dividend rights, liquidation preference or other preferences over Common Stock and has no voting rights except as provided in the Certificate of Designation for the Preferred Stock and as required by law. The Q3 2017 Offering and the Q1 2017 Offering were accounted for as extinguishments of the Investor’s equity holdings in recognition of the revisions of certain preexisting equity instruments and the significant transfer of value in excess of the funding received by the Company. Under the extinguishment model, a deemed dividend was recognized within additional paid in capital which represented the fair value of issued Preferred Stock plus the incremental fair value of repricing the Preferred Stock held by the Investor, less the fair value of the consideration transferred, less the carrying value of the outstanding Preferred Stock, and warrants to purchase Common Stock. The amount of the deemed dividend totaled $2.8 million and $4.0 million for the Q3 2017 Offering and the Q1 2017 Offering, respectively. The Company determined that equity classification was appropriate for the warrants issued in the Q1 2017 Offering, following guidance in the Derivatives and Hedging topic of the Codification. In making this equity classification determination, the Company noted the warrants may only be settled in shares of common stock and had no requirements to be settled in registered shares when exercised. The fair value of the five year warrants was estimated to be $3.5 million on the offering date using a Black-Scholes model with the following assumptions: stock price of $4.96 , exercise price of $5.60 , expected volatility of 70.2% , risk free interest rate of 2.04% , expected term of five years , and no dividends. During 2017 , 3,149.72 shares of the Series D Preferred Stock were converted into a total of 859,077 shares of common stock. As of December 31, 2017 , 14,052.93 shares of Series D Preferred Stock remained outstanding. During 2017 , 2,693.95 shares of the Series F Preferred Stock were converted into a total of 974,163 shares of common stock. As of December 31, 2017 , 7,927.05 shares of Series F Preferred Stock remained outstanding. 2016 activity In June 2016, the Company completed a private equity offering with one institutional investor (the “Investor”) and issued (i) 21,300 shares of Series D convertible preferred stock (the “Series D Preferred Stock”) at a price of $1,000 per share, and (ii) warrants to purchase up to 1,475,069 shares of common stock, par value $0.0001 per share (the “Common Stock”), at an exercise price of $13.52 per share (the “June 2016 Offering”). As a part of this offering, the Company redeemed 13,800 shares of Series C convertible preferred stock (the “Series C Preferred Stock”) issued in the December 2015 Offering that were held by the Investor. Accordingly, the June 2016 Offering resulted in gross proceeds of $7.5 million , and after deducting fees and expenses, net proceeds were $6.7 million . Each share of Series D Preferred Stock had a stated value of $1,000 and is convertible at the option of the holder into the number of shares of common stock determined by dividing the stated value by the conversion price of $14.44 , which is subject to adjustment as provided in the Certificate of Designation for the Series D Preferred Stock. The Series D Preferred Stock has no dividend rights, liquidation preference or other preferences over common stock and has no voting rights except as provided in the Certificate of Designation for the Series D Preferred Stock and as required by law. The June 2016 Offering was accounted for as a modification of the Investor’s Series C Preferred Stock. Under the modification model, a deemed dividend was recognized within retained earnings which represented the fair value of consideration transferred plus the fair value of repurchased Series C Preferred Stock, less the fair value of the newly issued Series D Preferred Stock and warrants. The amount of the deemed dividend totaled $19.8 million . The Company determined that equity classification was appropriate for the warrants in the June 2016, following guidance in the Derivatives and Hedging topic of the Codification. In making this equity classification determination, the Company noted the warrants had no requirements to be settled in registered shares when exercised. The fair value of the 5 year warrants issued in connection with the June 2016 Offering was estimated to be $14.6 million on the offering date using date using a Black-Scholes model with the following assumptions: stock price of $15.92 , exercise price of $13.52 , expected volatility of 71.50% , risk free interest rate of 1.23% , expected term of five years , and no dividends. During 2016 , 4,097.35 shares of the Series D Preferred Stock were converted into a total of 283,750 shares of common stock and 6,646 shares of the Series B Preferred Stock were converted into a total of 20,561 shares of common stock. Other equity activity In 2017, the Company issued 24,380 shares of fully vested common stock in exchange for 201,327 equity-classified warrants. The fair value of the warrants was estimated to be $45,102 on the exchange date using date using a Black-Scholes model with the following assumptions: stock price of $1.85 , exercise price of $15.19 , expected volatility of 70.0% , risk free interest rate of 2.0% , expected term of 3.8 years, and no dividends. In 2016 , the Company issued shares of fully vested common stock in partial settlement of management incentive compensation. The 2016 issuance totaled 22,260 shares with a value of $318,761 reflecting the $14.32 closing price of the Company’s common stock as reported on the Nasdaq Capital Market on March 9, 2016. As of December 31, 2017 , the Company had 100,000,000 shares of common stock authorized and 2,706,066 shares issued and outstanding. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of the Company’s stockholders. Common stockholders are not entitled to receive dividends unless declared by the Board of Directors. At December 31, 2017 , the Company has reserved authorized shares of common stock for future issuance as follows: Warrants 459,375 Outstanding stock options 80,537 Possible future issuance under inducement plan 12,500 Possible future issuance under stock option plans 618,247 Possible future issuance under employee stock purchase plan 58 Total 1,170,717 Reverse Stock Split On May 11, 2017, the Company effected a 1-for-8 reverse stock split of its Common Stock, or the Reverse Stock Split. The par value and other terms of the common stock were not affected by the Reverse Stock Split. The Company’s shares outstanding immediately prior to the split totaled 10,147,721 , which were subsequently adjusted to 1,268,440 shares outstanding. Share, per share, and stock option amounts for all periods presented within the financial statements contained in the Annual Report on Form 10-K have been retroactively adjusted to reflect the Reverse Stock Split.

Management Retention and Incent

Management Retention and Incentive Plan	12 Months Ended
	Dec. 31, 2017
Compensation and Retirement Disclosure [Abstract]
Management Retention and Incentive Plan	Management Retention and Incentive Plan The Company has adopted the Management Retention and Incentive Plan (the “Plan”), under which a portion of the consideration payable upon a change in control transaction, as defined in the Plan and its amendments, would be paid in cash to certain executive officers and key employees and recorded as compensation expense within the Statement of Operations during the period in which the change of control transaction occurs. The Plan is structured to work in conjunction with, and not replace, the Company’s other incentive programs and is designed to provide market-based incentives which will be reduced over time by any future equity grants to participants.

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event GSK Collaboration On January 12, 2018, the Company entered into an Asset Purchase Agreement with Novartis Consumer Health S.A., an affiliate of GlaxoSmithKline, or GSK, pursuant to which the Company sold to GSK its Quell technology for markets outside of the United States, including certain patents and related assets. The purchase price for the assets sold pursuant to the Asset Purchase Agreement was $5 million . the Company retained exclusive ownership of Quell technology in the U.S. market. The Company and GSK also entered into a Development and Services Agreement on January 12, 2018, pursuant to which the Company agreed to provide services related to the development, regulatory approval and commercialization of the Quell technology for markets outside of the U.S. Pursuant to the Development and Services Agreement, GSK has agreed to make contingent payments of up to $21.5 million to the Company upon the occurrence of certain development and commercialization milestones. In addition, GSK and the Company will co-fund development of next-generation Quell technology during an initial period of 2018 through 2020, with subsequent annual renewals by mutual agreement. The Company agreed not to compete with GSK with respect to the development and commercialization of the Quell technology and device outside of the U.S. until the tenth anniversary of the date of termination or expiration without renewal of the Development and Services Agreement. In connection with the Asset Purchase Agreement, the Company entered into a Contribution Agreement on December 22, 2017 with Quell Intellectual Property Corp., LLC, a newly formed Delaware limited liability company that was formed as a special purpose entity, and contributed certain intellectual property rights related to the Quell technology. Following the closing of the transactions contemplated by the Contribution Agreement and Asset Purchase Agreement, the Company and GSK each now own a 50% interest in Quell Intellectual Property Corp, LLC. Quell Intellectual Property Corp., LLC entered into two exclusive license agreements with the Company relating to rights to Quell intellectual property for use in the U.S. and in markets outside the U.S. Under the terms of an Assignment Agreement entered into on January 12, 2018, the Company assigned the ex-U.S. license agreement to GSK. These agreements are collectively referred to as the GSK Collaboration.

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
Schedule of Valuation and Qualifying Accounts Disclosure	Schedule II — Valuation and Qualifying Accounts Description Balance at Beginning of Period Charged to costs and expenses Charged to other accounts Recoveries/ (Deductions) Balance at End of Period December 31, 2017 Allowance for Doubtful Accounts $ 25,000 8,374 — (8,374 ) $ 25,000 Deferred Tax Asset Valuation Allowance 49,274,154 3,175,637 — (17,118,477 ) (1) 35,331,314 December 31, 2016 Allowance for Doubtful Accounts $ 25,000 1,901 — (1,901 ) $ 25,000 Deferred Tax Asset Valuation Allowance 43,660,035 5,867,273 — (253,154 ) (1) 49,274,154 (1) Expiration of Federal and State Net Operating Loss Carryforwards and other reductions.

Summary of Significant Accoun23

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Use of Estimates and Assumptions	Use of Estimates and Assumptions The preparation of financial statements in conformity with United States generally accepted accounting principles requires management to make significant estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during reporting periods. Actual results could differ from those estimates. The Company bases its estimates on historical experience and various other assumptions that it believes to be reasonable under the circumstances and regularly assesses these estimates, but actual results could differ materially from these estimates. Effects of changes in estimates are recorded in the period in which they occur.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments with an original maturity of ninety days or less to be cash equivalents. Cash equivalents are recorded at cost which approximates fair value. The Company invests cash primarily in a money market account and other investments which management believes are subject to minimal credit and market risk.
Concentrations of Credit Risk	Concentrations of Credit Risk Financial instruments that potentially expose the Company to concentrations of credit risk consist primarily of cash and cash equivalents in bank deposit accounts and trade receivables. The Company invests its funds in highly rated institutions and limits its investment in any individual account so that they do not exceed FDIC limits. The Company has not experienced significant losses related to cash and cash equivalents and does not believe it is exposed to any significant credit risks relating to its cash and cash equivalents. At December 31, 2017 and 2016 , two customers accounted for 66% and 41% of accounts receivable, respectively. For the years ended December 31, 2017 and 2016 , customers accounting for more than 10% of revenue were 19% and zero of revenues, respectively. The Company relies on in-house assembly and four third-party manufacturers to manufacture the major portion of its current products and product components. The disruption or termination of the supply of these products or a significant increase in the cost of these products from these sources could have an adverse effect on the Company’s business, financial position, and results of operations.
Inventories	Inventories Inventories, consisting primarily of finished goods and purchased components, are stated at the lower of cost or net realizable value. Cost is determined using the first-in, first-out method. The Company writes down inventory to its net realizable value for excess or obsolete inventory.
Fair Value	Fair Value The carrying amounts of the Company’s accounts receivable, accounts payable, and accrued expenses approximate their fair value at December 31, 2017 and 2016 due to the short-term nature of these assets and liabilities. The Company’s cash equivalents and its warrant liability are carried at fair value determined according to the fair value hierarchy described in Note 9.
Revenue Recognition	Revenue Recognition The Company recognizes revenue when the following criteria have been met: persuasive evidence of an arrangement exists, delivery has occurred and risk of loss has passed, the seller’s price to the buyer is fixed or determinable, and collection is reasonably assured. Revenues associated with the Company’s medical devices and consumables are generally recognized upon shipment, assuming all other revenue recognition criteria have been met. Revenue associated with shipments made to distributors who have the right to return any unsold product is recognized once the product is sold by the distributor to the end customer (i.e. under a sell-through model), assuming all other revenue recognition criteria have been met. Cash received prior to all the conditions for revenue recognition being met is recorded as deferred revenue. As of December 31, 2017 , the total value of shipments made to sell-through distributors but not yet sold through to end customers totaled $3,010,734 . Of this total, $2,190,703 was recorded as a reduction to accounts receivable and $820,031 was recorded in deferred revenue, as cash had been received. As of December 31, 2016 , the total value of shipments that had been made to sell-through distributors but have not yet been sold through to end customers totaled $1,247,545 . Of this total, $619,309 was recorded as a reduction to accounts receivable and $628,236 was recorded in deferred revenue, as cash had been received. Related costs of goods sold of $2,106,988 and $910,595 have been deferred and recorded in prepaid expenses and other current assets as of December 31, 2017 and 2016 , respectively. Revenue recognition involves judgments, including assessments of expected returns from customers who have the right to return product for any reason under 30-day or 60-day rights of return. Where the Company can reasonably estimate future returns, it recognizes revenues and records as a reduction of revenue a provision for estimated returns. The Company analyzes various factors, including its historical product returns in arriving at this judgment. Changes in judgments or estimates could materially impact the timing and amount of revenues and costs recognized.
Accounts Receivable	Accounts Receivable Accounts receivable are recorded net of the allowance for doubtful accounts receivable. The allowance for doubtful accounts is the Company’s best estimate of the amount of probable credit losses in our existing accounts receivable. The Company reviews the allowance for doubtful accounts and determines the allowance based on an analysis of customer past payment history, product usage activity, and recent communications with the customer. Individual customer balances which are past due and over 90 days outstanding are reviewed individually for collectability. Account balances are written-off against the allowance when the Company feels it is probable the receivable will not be recovered. The Company does not have any off-balance sheet credit exposure related to our customers.
Income Taxes	Income Taxes The Company records income taxes using the asset and liability method. Deferred income tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective income tax bases, and operating loss and tax credit carryforwards. The Company’s financial statements contain certain deferred tax assets, which have arisen primarily as a result of operating losses, as well as other temporary differences between financial and tax accounting. In accordance with the provisions of the Income Taxes topic of the Codification, the Company is required to establish a valuation allowance if the likelihood of realization of the deferred tax assets is reduced based on an evaluation of objective verifiable evidence. Significant management judgment is required in determining the Company’s provision for income taxes, the Company’s deferred tax assets and liabilities and any valuation allowance recorded against those net deferred tax assets. The Company evaluates the weight of all available evidence to determine whether it is more likely than not that some portion or all of the net deferred income tax assets will not be realized. Utilization of the NOL and research and development credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations that have occurred previously or that could occur in the future, as provided by Section 382 of the Internal Revenue Code of 1986, as well as similar state provisions. Ownership changes may limit the amount of NOL and tax credit carryforwards that can be utilized to offset future taxable income and tax, respectively. In general, an ownership change, as defined by Section 382, results from transactions increasing the ownership of certain shareholders or public groups in the stock of a corporation by more than 50 percentage points over a three-year period. If the Company has experienced a change of control, utilization of its NOL or tax credits carryforwards would be subject to an annual limitation under Section 382. Any limitation may result in expiration of a portion of the NOL or research and development credit carryforwards before utilization. Subsequent ownership changes could further impact the limitation in future years. Further, until a study is completed and any limitation known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s NOL carryforwards and research and development credit carryforwards and, if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the balance sheet or statement of operations if an adjustment were required. Management performed a two-step evaluation of all tax positions, ensuring that these tax return positions meet the “more likely than not” recognition threshold and can be measured with sufficient precision to determine the benefit recognized in the financial statements. These evaluations provide management with a comprehensive model for how a company should recognize, measure, present, and disclose in its financial statements certain tax positions that the Company has taken or expects to take on income tax returns.
Research and Development	Research and Development Costs incurred in research and development are expensed as incurred. Included in research and development costs are wages, benefits, product design consulting, and other operating costs such as facilities, supplies, and overhead directly related to the Company’s research and development efforts.
Product Warranty Costs	Product Warranty Costs The Company accrues estimated product warranty costs at the time of sale which are included in cost of sales in the statements of operations. The amount of the accrued warranty liability is based on historical information such as past experience, product failure rates, number of units repaired, and estimated cost of material and labor
Fixed Assets and Long-Lived Assets	Fixed Assets and Long-Lived Assets Fixed assets are recorded at cost and depreciated using the straight-line method over the estimated useful life of each asset. Expenditures for repairs and maintenance are charged to expense as incurred. On disposal, the related assets and accumulated depreciation are eliminated from the accounts and any resulting gain or loss is included in the Company’s statement of operations. Leasehold improvements are amortized over the shorter of the estimated useful life of the improvement or the remaining term of the lease. The Company periodically evaluates the recoverability of its fixed assets and other long-lived assets whenever events or changes in circumstances indicate that an event of impairment may have occurred. This periodic review may result in an adjustment of estimated depreciable lives or asset impairment. When indicators of impairment are present, the carrying values of the asset are evaluated in relation to the assets operating performance and future undiscounted cash flows of the underlying assets. If the future undiscounted cash flows are less than their book value, an impairment may exist. The impairment is measured as the difference between the book value and the fair value of the underlying asset. Fair values are based on estimates of the market prices and assumptions concerning the amount and timing of estimated future cash flows and assumed discount rates, reflecting varying degrees of perceived risk.
Accounting for Stock-Based Compensation	Accounting for Stock-Based Compensation Stock-based compensation cost is generally recognized ratably over the requisite service period. The Company uses the Black-Scholes option pricing model for determining the fair value of its stock options and amortizes its stock-based compensation expense using the straight-line method. The Black-Scholes model requires certain assumptions that involve judgment. Such assumptions are the expected share price volatility, expected life of options, expected annual dividend yield, and risk-free interest rate (See Note 3 — Stock-Based Compensation and Stockholders’ Equity).
Net Loss per Common Share	Net Loss per Common Share Basic net loss per common share is computed by dividing net loss applicable to common stockholders by the weighted average number of common shares outstanding during the period. Unvested restricted shares, although legally issued and outstanding, are not considered outstanding for purposes of calculating basic net loss per common share. Diluted net loss per common share is computed by dividing net loss by the weighted average number of common shares outstanding during the period plus the dilutive effect of the weighted average number of outstanding instruments such as options, warrants, restricted stock, and preferred stock. Because the Company has reported a net loss for all periods presented, diluted loss per common share is the same as basic loss per common share, as the effect of utilizing the fully diluted share count would have reduced the net loss per common share. Therefore, in calculating net loss per share amounts, shares underlying the following potentially dilutive weighted average number of common stock equivalents were excluded from the calculation of diluted net loss per common share because their effect was anti-dilutive for each of the periods presented: Years Ended December 31, 2017 2016 Options 99,344 52,725 Warrants 2,742,266 2,848,791 Convertible preferred stock 5,961,679 1,075,379 Total 8,803,289 3,976,895
Advertising and Promotional Costs	Advertising and Promotional Costs Advertising and promotional costs are expensed as incurred.
Accumulated Other Comprehensive Items	Accumulated Other Comprehensive Items For 2017 and 2016 , the Company had no components of other comprehensive income or loss other than net loss.
Segments	Segments The Company operates in one segment for the sale of medical equipment and consumables. Substantially all of the Company’s assets, revenues, and expenses for 2017 and 2016 , were located at or derived from operations in the United States. Revenues from sales outside the United States accounted for approximately 7% and 12% of total revenues in 2017 and 2016 , respectively.
Risks and Uncertainties	Risks and Uncertainties The Company is subject to risks common to companies in the medical device industry, including, but not limited to, development by the Company or its competitors of new technological innovations, dependence on key personnel, customers’ reimbursement from third-party payers, protection of proprietary technology, and compliance with regulations of the FDA and other governmental agencies.
Recently Issued or Adopted Accounting Pronouncements	Recently Issued or Adopted Accounting Pronouncements In February 2016, the FASB issued Accounting Standards Update No. 2016-2, Leases (Topic 842) (“ASU 2016-2”). ASU 2016-2 requires that lessees will need to recognize virtually all of their leases on the balance sheet, by recording a right-of-use asset and lease liability. The provisions of this guidance are effective for annual periods beginning after December 31, 2018, and for interim periods therein. The Company is in the process of evaluating the new standard and assessing the impact, if any, ASU 2016-2 will have on the Company’s Financial Statements. In May 2014, the FASB and the International Accounting Standards Board (“IASB”) jointly issued Accounting Standards Update (“ASU”) No. 2014-9, Revenue from Contracts with Customers (“ASU 2014-9”), a comprehensive new revenue recognition standard that will supersede nearly all existing revenue recognition guidance. The objective of ASU 2014-9 is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. While the Company is still in the process of completing its evaluation of the standard, it believes the most significant impact will be related to the timing of recognition of sales to certain consumer retail distributors. Upon adoption of ASU 2014-09, the Company will no longer be permitted to defer revenue under the sell-through model, but rather, will be required to estimate the effects of returns and allowances provided to distributors and record revenue at the time of sale to the distributor resulting in earlier recognition of revenues. The Company expects to adopt ASU 2014-09, using the full retrospective method, upon its effective date of January 1, 2018. The Company anticipates the impact of adoption will be a credit to accumulated deficit of approximately $0.3 million as of January 1, 2018

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule of Anti-Dilutive Securities	the following potentially dilutive weighted average number of common stock equivalents were excluded from the calculation of diluted net loss per common share because their effect was anti-dilutive for each of the periods presented: Years Ended December 31, 2017 2016 Options 99,344 52,725 Warrants 2,742,266 2,848,791 Convertible preferred stock 5,961,679 1,075,379 Total 8,803,289 3,976,895

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Schedule of Weighted Average Grant-Date Fair Value of Stock Options	The weighted average grant-date fair value of stock options used in the calculation of stock-based compensation expense in the accompanying statement of operations for the years ended December 31, 2017 and 2016 is calculated using the following assumptions: Years Ended December 31, 2017 2016 Risk-free interest rate 1.8- 2.1% 0.9- 1.8% Expected dividend yield — — Expected option term 5 years 5 years Volatility 70.0 % 70.0 %
Summary of Option Activity	A summary of option activity for the year ended December 31, 2017 is presented below: Number of Options Weighted Average Exercise Price Weighted Average Remaining Contractual Life (in years) Aggregate Intrinsic Value Outstanding at December 31, 2016 97,891 $ 37.95 Granted 6,488 2.37 Exercised — — Forfeited (23,825 ) 83.27 Expired (17 ) 11,187.28 Outstanding at December 31, 2017 80,537 19.32 8.6 $ — Vested or expected to vest at December 31, 2017 80,537 19.32 8.6 — Exercisable at December 31, 2017 25,388 37.26 8.3 —

Inventories (Tables)

Inventories (Tables)	12 Months Ended
	Dec. 31, 2017
Inventory Disclosure [Abstract]
Inventories	Inventories consist of the following: December 31, 2017 2016 Purchased components $ 505,293 $ 466,906 Work in progress — 154,971 Finished goods 864,354 630,361 $ 1,369,647 $ 1,252,238

Fixed Assets (Tables)

Fixed Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Fixed Assets	Fixed assets consist of the following: Estimated Useful Life (Years) December 31, 2017 2016 Computer and laboratory equipment 3 $ 881,969 $ 1,724,819 Furniture and equipment 3 227,845 319,046 Production equipment 7 346,469 938,357 Leasehold improvements * 117,994 117,994 1,574,277 3,100,216 Less – accumulated depreciation (1,133,435 ) (2,567,510 ) $ 440,842 $ 532,706 * Lesser of life of lease or estimated useful life.

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2017
Payables and Accruals [Abstract]
Accrued Compensation and Expenses	Accrued expenses consist of the following for the years ended December 31, 2017 and 2016 : December 31, 2017 2016 Sales return allowance $ 666,375 $ 488,200 Professional services 603,000 390,800 Technology fees 450,000 450,000 Advertising 160,800 28,100 Warranty 127,361 45,879 Other 234,779 245,752 $ 2,242,315 $ 1,648,731

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Reconciliation of Effective Income Tax Rate to Statutory Federal Rate	The Company’s effective income tax rate differs from the statutory federal income tax rate as follows for the years ended December 31, 2017 and 2016 . Years Ended December 31, 2017 2016 Federal tax provision (benefit) rate (34.0 )% (34.0 )% State tax provision, net of federal provision (5.9 ) (4.2 ) Permanent items (0.1 ) (0.2 ) Federal research and development credits (0.7 ) (0.9 ) Change in statutory tax rate 150.3 — Valuation allowance (109.6 ) 39.3 Effective income tax rate — —
Schedule of Deferred Tax Assets	The Company’s deferred tax assets consist of the following: December 31, 2017 2016 Deferred tax assets: Net operating loss carryforwards $ 31,902,006 $ 45,759,780 Research and development credit carryforwards 2,432,058 2,180,700 Accrued expenses 748,334 752,866 Stock-based compensation 229,676 566,487 Other 19,240 14,321 Total gross deferred tax assets 35,331,314 49,274,154 Valuation allowance (35,331,314 ) (49,274,154 ) Net deferred tax assets $ — $ —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Future Minimum Lease Payments Under Noncancelable Operating Leases	Future minimum lease payments under non-cancellable operating leases as of December 31, 2017 are as follows: 2018 573,421 2019 549,403 2020 475,408 2021 487,379 2022 81,562 Total minimum lease payments $ 2,167,173

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value Measurements	The following tables present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis for the periods presented and indicates the fair value hierarchy of the valuation techniques it utilized to determine such fair value. In general, fair values determined by Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities. Fair values determined by Level 2 inputs utilize data points that are observable such as quoted prices, interest rates, and yield curves. Fair values determined by Level 3 inputs are unobservable data points for the asset or liability, and include situations where there is little, if any, market activity for the asset or liability. December 31, 2017 Fair Value Measurements at December 31, 2017 Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 1,744,965 $ 1,744,965 $ — $ — Total $ 1,744,965 $ 1,744,965 $ — $ — December 31, 2016 Fair Value Measurements at December 31, 2016 Using Quoted Prices in Active Markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) Assets: Cash equivalents $ 833,831 $ 833,831 $ — $ — Total $ 833,831 $ 833,831 $ — $ — Liabilities: Common stock warrants $ 4,641 $ — $ — $ 4,641 Total $ 4,641 $ — $ — $ 4,641
Black-Scholes Inputs to Warrant Liability Valuation	Black-Scholes Inputs to Warrant Liability Valuation at December 31, 2016 Stock Price Exercise Price Expected Volatility Risk-Free Interest Expected Term Dividends Warrants: 2014 Offering $ 5.92 $ 65.28 64.19 % 1.33 % 2 years, 6 months none 2013 Offering $ 5.92 $ 64.00 71.61 % 0.99 % 1 year, 5 months none
Fair Value, Liabilities Measured on Recurring Basis	The following table provides a summary of changes in the fair value of the Company’s Level 3 financial liabilities between December 31, 2015 and December 31, 2017 . 2014 Offering 2013 Offering Total Balance at December 31, 2015 $ 227,992 $ 52,311 $ 280,303 Change in fair value of warrant liability (223,880 ) (51,782 ) (275,662 ) Balance at December 31, 2016 $ 4,112 $ 529 $ 4,641 Change in fair value of warrant liability from repricing (see Note 12) 177,999 66,612 244,611 Change in fair value of warrant liability (147,278 ) (61,202 ) (208,480 ) Repurchase and retirement of warrants (see Note 12) (34,833 ) (5,939 ) (40,772 ) Balance at December 31, 2017 $ — $ — $ —

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2017
Equity [Abstract]
Preferred stock and convertible preferred stock	Preferred stock and convertible preferred stock consist of the following: December 31, 2017 2016 Preferred stock, $0.001 par value; 5,000,000 shares authorized at December 31, 2017 and 2016; no shares issued and outstanding at December 31, 2017 and 2016 $ — $ — Series B convertible preferred stock, $0.001 par value, 147,000 shares designated at December 31, 2017 and 2016, and 500 shares issued and outstanding at December 31, 2017 and 2016 1 1 Series D convertible preferred stock, $0.001 par value, 21,300 and zero shares designated at December 31, 2017 and 2016, respectively, 14,052.93 and 17,202.65 shares issued and outstanding at December 31, 2017 and 2016, respectively 14 17 Series E convertible preferred stock, $0.001 par value, 7,000 and zero shares designated at December 31, 2017 and 2016, respectively, and 7,000 and zero shares issued and outstanding at December 31, 2017 and 2016, respectively 7 — Series F convertible preferred stock, $0.001 par value, 10,621 and zero shares designated at December 31, 2017 and 2016, respectively, and 7,927.05 and zero shares issued and outstanding at December 31, 2017 and 2016, respectively 8 —
Reserved Authorized Shares of Common Stock for Future Issuance	At December 31, 2017 , the Company has reserved authorized shares of common stock for future issuance as follows: Warrants 459,375 Outstanding stock options 80,537 Possible future issuance under inducement plan 12,500 Possible future issuance under stock option plans 618,247 Possible future issuance under employee stock purchase plan 58 Total 1,170,717

Description of Business and B33

Description of Business and Basis of Presentation - Additional Information (Detail) - USD ($)	Jan. 11, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Organization And Basis Of Presentation [Line Items]
Accumulated deficit		$ 191,338,054	$ 178,478,801
Cash and cash equivalents		4,043,681	$ 3,949,135	$ 12,462,872
2017 Offerings
Organization And Basis Of Presentation [Line Items]
Gross proceeds from issuance of equity		14,000,000
Net proceed from offering common stock and warrants		$ 12,900,000
Subsequent Event | Market Technology, Patents, and Related Assets
Organization And Basis Of Presentation [Line Items]
Proceeds from asset purchase agreement	$ 5,000,000
Contingent payments (up to)	$ 21,500,000

Summary of Significant Accoun34

Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Concentration Risk [Line Items]
Total value of shipments made to sell-through distributors but not yet sold through to end customers	$ 3,010,734	$ 1,247,545
Amount of shipments recorded as a reduction to accounts receivable	2,190,703	619,309
Amount of shipments included in deferred revenue	820,031	628,236
Related costs of goods sold deferred and recorded in prepaid expenses and other current assets	2,106,988	910,595
Accrued expense	666,375	488,200
Liabilities for product warranty costs	127,361	45,879
Advertising and promotion expense	$ 6,851,000	$ 6,311,000
Revenues from sales outside the United States, percentage	7.00%	12.00%
Accumulated deficit	$ (191,338,054)	$ (178,478,801)
Accounts Receivable | Two Customers
Concentration Risk [Line Items]
Concentration risk, percentage	66.00%	41.00%
Sales Revenue, Net | Customers
Concentration Risk [Line Items]
Concentration risk, percentage	19.00%	0.00%
Subsequent Event | ASU 2014-09 | Scenario, Forecast
Concentration Risk [Line Items]
Accumulated deficit			$ 300,000

Summary of Significant Accoun35

Summary of Significant Accounting Policies - Net Loss per Common Share (Details) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Class of Stock [Line Items]
Potentially dilutive common stock equivalents excluded from calculation of diluted net income per common share	8,803,289	3,976,895
Convertible preferred stock
Class of Stock [Line Items]
Potentially dilutive common stock equivalents excluded from calculation of diluted net income per common share	5,961,679	1,075,379
Warrants
Class of Stock [Line Items]
Potentially dilutive common stock equivalents excluded from calculation of diluted net income per common share	2,742,266	2,848,791
Options
Class of Stock [Line Items]
Potentially dilutive common stock equivalents excluded from calculation of diluted net income per common share	99,344	52,725

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($)	May 03, 2016	May 31, 2010	Jun. 30, 2004	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding (in shares)				80,537	97,891
Weighted average exercise price (in usd per share)				$ 19.32	$ 37.95
Weighted average grant-date fair value of options granted (in usd per share)				2.37	6.80
Aggregate instrinsic value of options issued or exercised				$ 0	$ 0
Unrecognized stock-based compensation costs related to non-vested stock options				$ 335,405
Non-vested stock options (in shares)				80,537
Weighted average fair value of non-vested stock options (in usd per share)				$ 19.32
Weighted average period of recognition				2 years 7 months
Stock-based compensation expense				$ 209,691	$ 225,408
2004 Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional shares authorized (in shares)	600,000
Expiration period				10 years
Shares authorized (in shares)				728,946
Shares issued in period (in shares)				30,162
Shares outstanding (in shares)				80,537
Weighted average exercise price (in usd per share)				$ 19.32
Shares available for future grant (in shares)				618,247
2004 Stock Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				3 years
2004 Stock Plan | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period				4 years
2009 Inducement Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)				12,500
2004 Stock Plan and 2009 Inducement Plan | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of combined voting power of all classes of stock				10.00%
Percentage of fair value of common stock at date of grant				110.00%
2004 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)			326
Award vesting rights			All of the Companys employees who had been employed by the Company for at least 60 days and whose customary employment is for more than 20 hours per week and for more than five months in any calendar year were eligible to participate and any employee who owned 5% or more of the voting power or value of the Companys stock was not eligible to participate.
2010 ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)		217				521
Shares issued in period (in shares)				11,583	4,375
Shares outstanding (in shares)				58
Percentage of fair value of common stock at date of grant				85.00%
Maximum percentage of earnings employee can authorize to withhold, percentage				10.00%
Award vesting rights		1,736 shares, (ii) 1 percent of the shares of common stock outstanding on the last day of the immediately preceding fiscal year, or (iii) such lesser number of shares as is determined by the Board. At the Companys Annual Meeting of Stockholders held on May 3, 2016, the stockholders of the Company approved the Companys Third Amended and Restated 2010 Employee Stock Purchase Plan (the Amended and Restated 2010 ESPP), which, among other things, increased the number of shares of the Companys common stock authorized for issuance thereunder by 100,000 shares. All of the Companys full-time employees and certain part-time employees are eligible to participate in the Amended and Restated 2010 ESPP. For part-time employees to be eligible, they must have customary employment of more than five months in any calendar year and more than 20 hours per week. Employees who, after exercising their rights to purchase shares under the Amended and Restated 2010 ESPP, would own shares representing 5% or more of the voting power of the Companys common stock, are ineligible to participate.
2004 and 2010 ESPPs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash received from option exercises and purchases				$ 20,768	$ 28,538

Stock-Based Compensation - Weig

Stock-Based Compensation - Weighted Average Grant-Date Fair Value Used in the Calculation of Stock-Based Compensation Expense (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%
Expected option term	5 years	5 years
Volatility	70.00%	70.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.80%	0.90%
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	2.10%	1.80%

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Option Activity (Details)	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Number of Options
Number of options outstanding, beginning balance (in shares) | shares	97,891
Number of options granted (in shares) | shares	6,488
Number of options exercised (in shares) | shares	0
Number of options forfeited (in shares) | shares	(23,825)
Number of options expired (in shares) | shares	(17)
Number of options outstanding, ending balance (in shares) | shares	80,537
Number of options vested or expected to vest (in shares) | shares	80,537
Number of options exercisable (in shares) | shares	25,388
Weighted Average Exercise Price
Weighted average exercise price of options outstanding, beginning of period (in usd per share) | $ / shares	$ 37.95
Weighted average exercise price of options granted (in usd per share) | $ / shares	2.37
Weighted average exercise price of options exercised (in usd per share) | $ / shares	0
Weighted average exercise price of options forfeited (in usd per share) | $ / shares	83.27
Weighted average exercise price of options expired (in usd per share) | $ / shares	11,187.28
Weighted average exercise price of options outstanding, end of period (in usd per share) | $ / shares	19.32
Weighted average exercise price of options vested or expected to vest (in usd per share) | $ / shares	19.32
Weighted average exercise price of options exercisable (in usd per share) | $ / shares	$ 37.26
Weighted Average Remaining Contractual Life (in years) and Aggregate Intrinsic Value
Weighted average remaining contractual life of options outstanding (in years)	8 years 7 months 6 days
Weighted average remaining contractual life of options vested or expected to vest (in years)	8 years 7 months 6 days
Weighted average remaining contractual life of options exercisable (in years)	8 years 3 months 18 days
Aggregate intrinsic value of options outstanding | $	$ 0
Aggregate intrinsic value of options vested and expected to vest | $	0
Aggregate intrinsic value of options exercisable | $	$ 0

Inventories (Detail)

Inventories (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Inventory Disclosure [Abstract]
Purchased components	$ 505,293	$ 466,906
Work in progress	0	154,971
Finished goods	864,354	630,361
Inventories	$ 1,369,647	$ 1,252,238

Fixed Assets (Details)

Fixed Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Fixed assets, gross	$ 1,574,277	$ 3,100,216
Less – accumulated depreciation	(1,133,435)	(2,567,510)
Fixed assets, net	$ 440,842	532,706
Computer and laboratory equipment
Property, Plant and Equipment [Line Items]
Fixed assets, estimated useful life	3 years
Fixed assets, gross	$ 881,969	1,724,819
Furniture and equipment
Property, Plant and Equipment [Line Items]
Fixed assets, estimated useful life	3 years
Fixed assets, gross	$ 227,845	319,046
Production equipment
Property, Plant and Equipment [Line Items]
Fixed assets, estimated useful life	7 years
Fixed assets, gross	$ 346,469	938,357
Leasehold improvements
Property, Plant and Equipment [Line Items]
Fixed assets, estimated useful life
Fixed assets, gross	$ 117,994	$ 117,994

Fixed Assets - Additional Infor

Fixed Assets - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 262,334	$ 251,327

Accrued Expenses (Detail)

Accrued Expenses (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Payables and Accruals [Abstract]
Sales return allowance	$ 666,375	$ 488,200
Professional services	603,000	390,800
Technology fees	450,000	450,000
Advertising	160,800	28,100
Warranty	127,361	45,879
Other	234,779	245,752
Accrued expenses	$ 2,242,315	$ 1,648,731

Income Taxes Income Taxes - Eff

Income Taxes Income Taxes - Effective Income Tax Rate Reconciliation (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal tax provision (benefit) rate	34.00%	34.00%
State tax provision, net of federal provision	(5.90%)	(4.20%)
Permanent items	(0.10%)	(0.20%)
Federal research and development credits	(0.70%)	(0.90%)
Change in statutory tax rate	150.30%	0.00%
Valuation allowance	(109.60%)	39.30%
Effective income tax rate	0.00%	0.00%

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Tax Credit Carryforward [Line Items]
Tax benefits attributable to NOL	$ 2,600,000
Tax benefits attributable to tax credit caryforwards	71,238
Deferred tax assets, valuation allowance	35,331,314	$ 49,274,154
Federal Tax Authority
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	145,200,000
Tax credit carryforwards	1,500,000
State Tax Authority
Tax Credit Carryforward [Line Items]
Net operating loss carryforwards	51,600,000
Tax credit carryforwards	$ 1,100,000

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 31,902,006	$ 45,759,780
Research and development credit carryforwards	2,432,058	2,180,700
Accrued expenses	748,334	752,866
Stock-based compensation	229,676	566,487
Other	19,240	14,321
Total gross deferred tax assets	35,331,314	49,274,154
Valuation allowance	(35,331,314)	(49,274,154)
Net deferred tax assets	$ 0	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Feb. 20, 2015	Sep. 30, 2014USD ($)	Aug. 31, 2014USD ($)extension_option	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Operating Leased Assets [Line Items]
Total recorded rent expense				$ 670,860	$ 581,928
Commitments comprised of purchase orders				4,218,229
5-year operating lease agreement
Operating Leased Assets [Line Items]
Operating lease, term of contract			5 years
Operating lease, number of extension options | extension_option			1
Operating lease, renewal term			5 years
Monthly base rent			$ 7,815
7-year operating lease agreement
Operating Leased Assets [Line Items]
Operating lease, term of contract	7 years	7 years
Operating lease, number of extension options | extension_option			1
Operating lease, renewal term			5 years
Monthly base rent		$ 37,788
Excess cost of leasehold improvements				$ 275,961

Commitments and Contingencies47

Commitments and Contingencies - Future Minimum Lease Payments (Details)	Dec. 31, 2017USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,018	$ 573,421
2,019	549,403
2,020	475,408
2,021	487,379
2,022	81,562
Total minimum lease payments	$ 2,167,173

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash equivalents	$ 1,744,965
Total assets measured at fair value on recurring basis	1,744,965
Liabilities [Abstract]
Common stock warrants		$ 4,641
Fair Value, Measurements, Recurring
Assets
Cash equivalents		833,831
Total assets measured at fair value on recurring basis		833,831
Liabilities [Abstract]
Common stock warrants		4,641
Total liabilities measured at fair value on recurring basis		4,641
Fair Value, Measurements, Recurring | Level 1
Assets
Cash equivalents	1,744,965	833,831
Total assets measured at fair value on recurring basis	1,744,965	833,831
Liabilities [Abstract]
Common stock warrants		0
Total liabilities measured at fair value on recurring basis		0
Fair Value, Measurements, Recurring | Level 2
Assets
Cash equivalents	0	0
Total assets measured at fair value on recurring basis	0	0
Liabilities [Abstract]
Common stock warrants		0
Total liabilities measured at fair value on recurring basis		0
Fair Value, Measurements, Recurring | Level 3
Assets
Cash equivalents	0	0
Total assets measured at fair value on recurring basis	$ 0	0
Liabilities [Abstract]
Common stock warrants		4,641
Total liabilities measured at fair value on recurring basis		$ 4,641

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Fair Value of Company's Level 3 Financial Liabilities (Details) - Warrants - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	$ 4,641	$ 280,303
Change in fair value of warrant liability		(275,662)
Change in fair value of warrant liability from repricing	244,611
Change in fair value of warrant liability	(208,480)
Repurchase and retirement of warrants	(40,772)
Ending balance	0	4,641
2014 Offering
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	4,112	227,992
Change in fair value of warrant liability		(223,880)
Change in fair value of warrant liability from repricing	177,999
Change in fair value of warrant liability	(147,278)
Repurchase and retirement of warrants	(34,833)
Ending balance	0	4,112
2013 Offering
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Beginning balance	529	52,311
Change in fair value of warrant liability		(51,782)
Change in fair value of warrant liability from repricing	66,612
Change in fair value of warrant liability	(61,202)
Repurchase and retirement of warrants	(5,939)
Ending balance	$ 0	$ 529

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Detail)	Dec. 31, 2016USD ($)
Fair Value Disclosures [Abstract]
Common stock warrants liability	$ 4,641

Fair Value Measurements - Black

Fair Value Measurements - Black-Scholes Inputs to Warrant Liability Valuation (Details)	12 Months Ended
	Dec. 31, 2017$ / shares
2014 Offering
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock Price	$ 5.92
Exercise Price	$ 65.28
Expected Volatility	64.19%
Risk-Free Interest	1.33%
Expected Term	2 years 6 months
Dividends	0.00%
2013 Offering
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Stock Price	$ 5.92
Exercise Price	$ 64
Expected Volatility	71.61%
Risk-Free Interest	0.99%
Expected Term	1 year 5 months
Dividends	0.00%

Retirement Plan Retirement Plan

Retirement Plan Retirement Plan - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Contributions to the plan	$ 0	$ 0

Credit Facility - Additional In

Credit Facility - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Line of Credit Facility [Line Items]
Revolving credit facility, maximum borrowing capacity	$ 2.5
Credit facility expiration date	Jan. 15, 2019
Credit facility limit restricted to support letter of credit	$ 0.2
Line of credit facility, remaining borrowing capacity	$ 2.3
Prime Rate
Line of Credit Facility [Line Items]
Interest rate over prime rate	0.50%

Stockholders' Equity - Preferre

Stockholders' Equity - Preferred Stock and Convertible Preferred Stock (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Preferred stock
Class of Stock [Line Items]
Preferred stock	$ 0	$ 0
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock	1	1
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock	14	17
Series E Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock	7	0
Series F Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock	$ 8	$ 0

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended	12 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Mar. 31, 2017	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	May 12, 2017	May 11, 2017
Class of Stock [Line Items]
Common stock, par value (in dollars per share)						$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)						100,000,000	100,000,000
Common stock, shares issued (in shares)						2,706,066	836,863
Common stock, shares outstanding (in shares)						2,706,066	836,863	1,268,440	10,147,721
Common Stock
Class of Stock [Line Items]
Issuance of common stock in exchange for warrants (in shares)						24,380
Common Stock From Series D Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued upon conversion (in shares)						859,077	283,750
Common Stock From Series F Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued upon conversion (in shares)						974,163
Common Stock From Series B Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued upon conversion (in shares)							20,561
2017 Offerings
Class of Stock [Line Items]
Gross proceeds from issuance of equity						$ 14,000,000
Net proceed from offering common stock and warrants						$ 12,900,000
Q1 2017 Offering
Class of Stock [Line Items]
Gross proceeds from issuance of equity				$ 7,000,000
Net proceed from offering common stock and warrants				$ 6,300,000
Q1 2017 Offering | Common Stock
Class of Stock [Line Items]
Shares of common stock available to purchase (in shares)				1,250,000
Common stock, par value (in dollars per share)				$ 0.0001
Number of securities available to purchase by warrants or rights				2,934,484
Q1 2017 Offering | Warrants
Class of Stock [Line Items]
Exercise price of warrants or rights (in dollars per share)				$ 5.6
Class of warrant exercisable period				5 years
Warrants not settleable in cash, fair value disclosure				$ 3,500,000
Exercise price (in dollars per share)				$ 4.96
Expected Volatility				70.20%
Risk-Free Interest				2.04%
Expected term				5 years
Expected dividends				0.00%
Q3 2017 Offering
Class of Stock [Line Items]
Gross proceeds from issuance of equity			$ 7,000,000
Net proceed from offering common stock and warrants			$ 6,600,000
June 2016 Offering
Class of Stock [Line Items]
Gross proceeds from issuance of equity	$ 7,500,000
Net proceed from offering common stock and warrants	$ 6,700,000
Class of warrant exercisable period						5 years
Warrants not settleable in cash, fair value disclosure						$ 14,600,000
Expected Volatility						71.50%
Risk-Free Interest						1.23%
Expected dividends						0.00%
Share price (in dollars per share)						$ 15.92
June 2016 Offering | Common Stock
Class of Stock [Line Items]
Shares of common stock available to purchase (in shares)	1,475,069
Common stock, par value (in dollars per share)	$ 0.0001
Exercise price of warrants or rights (in dollars per share)	13.52					$ 13.52
Other 2017 Equity Activity
Class of Stock [Line Items]
Issuance of common stock in exchange for warrants (in shares)						24,380
Warrants issued (in shares)						201,327
Expected dividends						0.00%
Other 2017 Equity Activity | Warrants
Class of Stock [Line Items]
Exercise price of warrants or rights (in dollars per share)						$ 15.19
Warrants not settleable in cash, fair value disclosure						$ 45,102
Exercise price (in dollars per share)						$ 1.85
Expected Volatility						70.00%
Risk-Free Interest						2.00%
Expected term						3 years 9 months 18 days
2016 Issuance | 2016 Management Incentive Compensation
Class of Stock [Line Items]
Shares issued during period (in shares)		22,260
Stock issued during period		$ 318,761
Closing price of shares		$ 14.32
Preferred stock
Class of Stock [Line Items]
Preferred stock, par value (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)						0	0
Preferred stock, outstanding (in shares)						0	0
Series F Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)						$ 0.001	$ 0.001
Preferred stock, shares designated (in shares)						10,621	0
Preferred stock, shares issued (in shares)						7,927.05	0
Preferred stock, outstanding (in shares)						7,927.05	0
Shares converted (in shares)						2,693.95
Series F Convertible Preferred Stock | Q3 2017 Offering
Class of Stock [Line Items]
Shares issued during period (in shares)			7,000
Shares issued (in dollars per share)			$ 1,000		$ 1,000
Gross proceeds from issuance of equity			$ 3,622,219
Shares of common stock available to purchase (in shares)			3,621		3,621
Number of shares authorized to be repurchased (in shares)			4,184,483		4,184,483
Series D Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)						$ 0.001	$ 0.001
Preferred stock, shares designated (in shares)						21,300	21,300
Preferred stock, shares issued (in shares)						14,052.93	17,202.65
Preferred stock, outstanding (in shares)						14,052.93	17,202.65
Shares converted (in shares)						3,149.72	4,097.35
Series D Convertible Preferred Stock | Q1 2017 Offering
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)				19,458.90
Series D Convertible Preferred Stock | Q3 2017 Offering
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			14,052.93		14,052.93
Series D Convertible Preferred Stock | June 2016 Offering
Class of Stock [Line Items]
Shares issued (in dollars per share)	$ 1,000
Shares issued during period (in shares)	21,300
Share price (in dollars per share)						$ 1,000
Preferred stock conversion price (in dollars per share)						14.44
Series E Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)						$ 0.001	$ 0.001
Preferred stock, shares designated (in shares)						7,000	0
Preferred stock, shares issued (in shares)						7,000	0
Preferred stock, outstanding (in shares)						7,000	0
Series E Convertible Preferred Stock | Q1 2017 Offering
Class of Stock [Line Items]
Shares issued during period (in shares)				7,000
Shares issued (in dollars per share)				$ 1,000
Series E Convertible Preferred Stock | Q3 2017 Offering
Class of Stock [Line Items]
Preferred stock, outstanding (in shares)			7,000		7,000
Series B – F Preferred Stock | 2017 Offerings
Class of Stock [Line Items]
Shares issued (in dollars per share)			$ 1,000		$ 1,000
Convertible preferred stock, conversion price (in dollars per share)					2.63
Series B – F Preferred Stock | Q1 2017 Offering
Class of Stock [Line Items]
Dividends, preferred stock, total				$ 4,000,000
Series B – F Preferred Stock | Q3 2017 Offering
Class of Stock [Line Items]
Convertible preferred stock, conversion price (in dollars per share)					$ 2.63
Dividends, preferred stock, total			$ 2,800,000
Series C Preferred Stock | June 2016 Offering
Class of Stock [Line Items]
Dividends, preferred stock, total						$ 19,800,000
Stock redeemed during period (in shares)	13,800
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)						$ 0.001	$ 0.001
Preferred stock, shares designated (in shares)						147,000	147,000
Preferred stock, shares issued (in shares)						500	500
Preferred stock, outstanding (in shares)						500	500
Shares converted (in shares)							6,646

Stockholders' Equity - Common S

Stockholders' Equity - Common Stock Reserved for Future Issuance (Details)	Dec. 31, 2017shares
Class of Stock [Line Items]
Total common shares reserved for future issuance	1,170,717
Inducement Plan
Class of Stock [Line Items]
Total common shares reserved for future issuance	12,500
Stock Option Plans
Class of Stock [Line Items]
Total common shares reserved for future issuance	618,247
Employee Stock Purchase Plan
Class of Stock [Line Items]
Total common shares reserved for future issuance	58
Options
Class of Stock [Line Items]
Total common shares reserved for future issuance	80,537
Warrants
Class of Stock [Line Items]
Total common shares reserved for future issuance	459,375

Reverse Stock Split - Additiona

Reverse Stock Split - Additional Information (Detail)	May 12, 2017shares	Dec. 31, 2017shares	May 11, 2017shares	Dec. 31, 2016shares
Equity [Abstract]
Common stock, shares outstanding (in shares)	1,268,440	2,706,066	10,147,721	836,863
Reverse stock split conversion ratio	0.125

Subsequent Event - Additional I

Subsequent Event - Additional Information (Detail) - Subsequent Event $ in Millions	Jan. 11, 2018USD ($)
Subsequent Event [Line Items]
Company's percent interest owned	50.00%
Market Technology, Patents, and Related Assets
Subsequent Event [Line Items]
Proceeds from asset purchase agreement	$ 5
Contingent payments (up to)	$ 21.5

Schedule II - Valuation and Q59

Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 25,000	$ 25,000
Charged to costs and expenses	8,374	1,901
Charged to other accounts	0	0
Recoveries/ (Deductions)	(8,374)	(1,901)
Balance at End of Period	25,000	25,000
Deferred Tax Asset Valuation Allowance
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	49,274,154	43,660,035
Charged to costs and expenses	3,175,637	5,867,273
Charged to other accounts	0	0
Recoveries/ (Deductions)	(17,118,477)	(253,154)
Balance at End of Period	$ 35,331,314	$ 49,274,154