0001625101-22-000016 | 10-K | XBRL Viewer

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Summary Of Significant Accounting Policies (Anti-Dilutive Shares Excluded From Computation Of Diluted Net Loss Per Share) (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	5,996,813	5,762,809	4,139,639
Common Stock Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total		612,310	167,847
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total	5,996,813	5,039,194	3,749,186
Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total		111,305	222,606

Investments And Fair Value Of Financial Instruments	12 Months Ended
Investments And Fair Value Of Financial Instruments	Dec. 31, 2021
Investments And Fair Value Of Financial Instruments [Abstract]
Investments And Fair Value Of Financial Instruments	3. Investments and Fair Value of Financial Instruments Investments The Company’s investments have been classified and accounted for as available-for-sale. At December 31, 2021 the Company had no investments outstanding. The Company’s investments consisted of the following at December 31, 2020 (in thousands): December 31, 2020 Cost Gross Unrealized Gains Gross Unrealized Losses Fair ValueU.S. Treasury securities $ 8,013 $— $ (1) $ 8,012Total assets measured at fair value $ 8,013 $— $— $ 8,012 The contractual maturities of the Company’s investments were as follows (in thousands): December 31, 2021 2020Due in one year $ — $ 8,012Due in one to two years — —Total $ — $ 8,012 Fair Value of Financial Instruments The Company determines the fair value of its financial instruments based on a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value into three levels: Level 1 – Observable inputs such as quoted prices in active markets for an identical asset or liability that the Company has the ability to access as of the measurement date. Financial assets and liabilities utilizing Level 1 inputs include money market funds. Level 2 – Inputs, other than quoted prices included within Level 1, which are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. Financial assets and liabilities utilizing Level 2 inputs include commercial paper, corporate bonds and asset-backed securities. Level 3 – Unobservable inputs in which there is little or no market data for the asset or liability which requires the reporting entity to develop its own assumptions. The Company did not classify any of its investments within Level 3 of the fair value hierarchy. The following table sets forth the fair value of the Company’s financial assets measured on a recurring basis (in thousands): December 31, 2021 Assets Classification Level 1 Level 2 Level 3 Total Money market funds Cash and cash equivalents $ 23,675 $— $— $ 23,675 Total assets measured at fair value $ 23,675 $ - $— $ 23,675 December 31, 2020Assets Classification Level 1 Level 2 Level 3 Total Money market funds Cash and cash equivalents $ 7,176 $— $— $ 7,176 U.S. Treasury securities Cash and cash equivalents — 2,004 — 2,004 U.S. Treasury securities Investments — 8,012 — 8,012 Total assets measured at fair value $ 7,176 $ 10,016 $— $ 17,192 During year ended December 31, 2021 and 2020, the Company did not record impairment charges related to its marketable investments. During the years ended December 31, 2021 and 2020, the Company did not have any transfers between Level 1, Level 2 or Level 3 of the fair value hierarchy. Additionally, the Company did not have any financial assets and liabilities measured at fair value on a non-recurring basis as of December 31, 2021 or 2020.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Consolidated Statement of Stockholders' Equity [Abstract]
Issuance of common stock and warrants in connection with rights offering, exercise price per unit		$ 7.01
Issuance of common stock, issuance costs	$ 568	$ 565
Issuance of common stock as part of debt extinguishment and private investment, issuance costs	$ 106

Balance Sheet Components (Tables)	12 Months Ended
Balance Sheet Components (Tables)	Dec. 31, 2021
Balance Sheet Components [Abstract]
Schedule Of Inventory	Year Ended December 31, 2021 2020Raw materials $ 2,010 $ —Work in process 1,371 —Finished goods 2,443 — Total inventory $ 5,824 $ —
Schedule Of Property And Equipment, Net	December 31, 2021 2020Leasehold improvements $ 2,519 $ 2,805Laboratory equipment 1,019 878Furniture, fixtures and equipment 932 517Software 202 128Construction in progress 186 66 4,858 4,394Less: Accumulated depreciation and amortization (2,396) (1,916) $ 2,462 $ 2,478
Schedule Of Intangible Assets, Net	December 31, 2021 2020Acquired patents and licenses $ 7,985 $ 7,985Less: Accumulated amortization (4,769) (4,103) $ 3,216 $ 3,882
Schedule Of Amortization Of Intangible Assets	Years ending December 31: 2022 $ 6652023 6652024 6652025 6652026 556 $ 3,216
Schedule Of Accrued Expenses	December 31, 2021 2020Compensation expense $ 2,932 $ 3,324Controlled launch (Note 8) 534 —Director and officer liability insurance (Note 12) — 1,563Clinical trial fees and costs 245 188Professional fees 85 87Warranty 80 —Other 513 164 $ 4,389 $ 5,326

Investments And Fair Value Of Financial Instruments (Schedule Of Contractual Maturities Of Investments) (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Investments And Fair Value Of Financial Instruments [Abstract]
Due in one year	$ 8,012
Total	$ 8,012

Commitments And Contingencies (Schedule Of Information Related To Right-Of-Use Assets And Lease Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Commitments And Contingencies [Abstract]
Current operating lease liabilities	$ 774	$ 542
Non-current operating lease liabilities	10,040	$ 10,814
Total lease liabilities	10,814
Cash paid for operating lease liabilities	$ 1,643
Weighted average remaining lease term	7 years 9 months 29 days
Weighted average discount rate	10.00%

Commitments And Contingencies (Schedule Of Maturity Lease Payments) (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Commitments And Contingencies [Abstract]
2022	$ 1,806
2023	1,845
2024	1,910
2025	1,977
2026	2,046
Thereafter	6,191
Total lease payments	15,775
Less imputed interest	(4,961)
Total lease liabilities	$ 10,814

Description Of The Business	12 Months Ended
Description Of The Business	Dec. 31, 2021
Description Of The Business [Abstract]
Description Of The Business	1. Description of the Business Pulse Biosciences, Inc. is a novel bioelectric medicine company committed to health innovation using an entirely new and proprietary energy modality. The Company’s CellFX System is the first commercial product to harness the distinctive advantages of the Company’s proprietary NPS technology. The CellFX System delivers nanosecond duration pulses of electrical energy, each less than a millionth of a second long, to non-thermally clear targeted cells while sparing adjacent non-cellular tissue, to treat a variety of medical conditions for which an optimal solution remains unfulfilled. In February 2021, the Company received 510(k) clearance from the FDA for the CellFX System for dermatologic procedures requiring ablation and resurfacing of the skin. In January 2021, the Company received CE marking approval for the CellFX System, which allows for marketing of the system in the EU and, in June 2021, the Company received Health Canada approval for the CellFX System, which allows for marketing of the system in Canada. The CE mark and Health Canada approvals allow for use of the CellFX System in dermatological procedures requiring ablation and resurfacing of the skin for the reduction, removal, and/or clearance of cellular-based benign lesions, including SH, SK, and cutaneous non-genital warts. The Company will continue to pursue specific indications for the CellFX System in the United States similar to the regulatory clearances already received in Europe and Canada. This will require additional 510(k) submissions for each subsequent indication, and will likely be based on comparative clinical data. In December 2021, the Company submitted a 510(k) to add the treatment of SH to the CellFX System’s indications for use in the United States. In February 2022 the Company received an AI letter from the FDA in response to the 510(k) submitted. In the AI letter, the FDA stated it did not believe the Company provided sufficient clinical evidence at this time to support the expanded indication for use, and that the Company had not met the primary endpoints of the SH FDA-approved IDE study. The Company anticipates meeting with the FDA to discuss the contents of the AI letter and potential next steps, which may require additional clinical data and potentially a new 510(k) submission. In February 2021, the Company initiated controlled launch programs (Note 8) in the United States and the European Union and in June 2021 the Company initiated a controlled launch program in Canada (collectively, our “Controlled Launch”). In August 2021, the Company began to convert Controlled Launch Program participants into sales agreements, thereby triggering revenue recognition. The Company was incorporated in Nevada on May 19, 2014. On June 18, 2018, the Company reincorporated from the State of Nevada to the State of Delaware. The Company is located in Hayward, California. The Company’s activities are subject to significant risks and uncertainties, including the need for additional capital. The Company does not currently have any cash flows from operations. It has recently commenced revenue-generating operations and will need to raise additional capital to finance its operations. However, there can be no assurances that the Company will be able to obtain additional financing on acceptable terms and in the amounts necessary to fully fund its operating requirements.

Stockholders' Equity And Stock-Based Compensation (Summary Of Performance Option Activity) (Details) - Performance Shares [Member] - 2017 And Inducement Plans [Member] - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	983,842
Options granted, Number of shares	216,255
Ending Balance, Number of shares	1,200,097	983,842
Exercisable, Number of shares	293,172
Beginning Balance, Weighted average exercise price per share	$ 11.06
Options granted, Weighted average exercise price per share	22.41
Ending Balance, Weighted average exercise price per share	13.11	$ 11.06
Exercisable, Weighted average exercise price per share	$ 11.64
Weighted average remaining life	8 years 5 months 8 days	8 years 3 months
Weighted average remaining life, exercisable	8 years 29 days

Investments And Fair Value Of Financial Instruments (Schedule Of Available-For-Sale Securities) (Details) $ in Thousands	Dec. 31, 2020 USD ($)
Schedule Of Available For Sale Securities [Line Items]
Cost	$ 8,013
Fair Value	8,012
US Treasury Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Cost	8,013
Gross Unrealized Losses	(1)
Fair Value	$ 8,012

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock Warrant Activity) (Details) - Common Stock Warrants [Member] - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	612,310
Options granted, Number of shares
Options exercised, Number of shares	(585,069)
Options expired/Redeemed, Number of shares	(27,241)
Ending Balance, Number of shares		612,310
Beginning Balance, Weighted average exercise price per share	$ 6.40
Options granted, Weighted average exercise price per share
Options exercised, Weighted average exercise price per share	6.47
Options expired, Weighted average exercise price per share	3.56
Ending Balance, Weighted average exercise price per share		$ 6.40
Weighted average remaining life		3 months 3 days

Research Grants And Agreements (Narrative) (Details) - USD ($) $ in Thousands	1 Months Ended				12 Months Ended
	May 31, 2021	Mar. 31, 2021	Sep. 30, 2019	Aug. 31, 2018	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense					$ 28,640	$ 26,444	$ 24,961
Sponsored Research Agreement ("SRA") [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense					300	$ 600	$ 900
Research and development expense payable					$ 300
ODURF [Member] \| Sponsored Research Agreement ("SRA") [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense	$ 300	$ 300	$ 800	$ 800
Period of time for Sponsored Research Agreement ("SRA")	12 months	12 months	12 months	12 months

Controlled Launch	12 Months Ended
Controlled Launch	Dec. 31, 2021
Controlled Launch [Abstract]
Controlled Launch	8. Controlled Launch In February 2021, the Company received 510(k) clearance from the U.S. FDA for its proprietary CellFX System for dermatologic procedures requiring ablation and resurfacing of the skin. In January 2021, the Company received CE marking approval for the CellFX System, which allows for marketing of the system in the EU for treatment of general dermatologic conditions, including SH, SK, and cutaneous non-genital warts. Additionally, in June 2021 the Company received Health Canada approval for the CellFX System, which allows for marketing of the system in Canada for use in dermatological procedures requiring ablation and resurfacing of the skin for the reduction, removal, and/or clearance of cellular-based benign lesions. In February 2021, the Company commenced a controlled launch of the CellFX System in the United States and European Union via its CellFX Expectations Excelled Program (the “Controlled Launch”). Subsequent to receiving Health Canada approval in June 2021, the Company also commenced a its Controlled Launch in Canada. As part of the Controlled Launch, the Company selected 70 physicians and their practices to be the first physician consultants to launch the CellFX System and the associated CellFX commercial procedures into their respective markets and geographies. According to the Controlled Launch program, the Company provides and sets up a CellFX System at each physician site and provides the physician with the necessary related products and components, free of charge, to complete the requirements of the Controlled Launch. Each CellFX System and any unused component products remain the property of the Company throughout the Controlled Launch. Each physician identifies and recruits up to 40 or 50 patients, depending on the contract, for participation in the Controlled Launch, performing a CellFX procedure on each of the appropriately selected patients. Under the Controlled Launch, the physician and their patients complete evaluation surveys about their experiences with the CellFX System and provide other information helpful to the Company. Upon completion of the procedures and the survey feedback, the physician earns either credits which can be used towards the future purchase of the CellFX System or, in some jurisdictions, fair payment for their time and effort completing the paperwork required under the Controlled Launch program. Credits earned and, if applicable, any other payments earned are limited to a maximum amount dependent on the number of surveys received by the Company. Upon completion of the Controlled Launch, each physician may choose to either enter into a purchase agreement with the Company, under which the physician may use the credits earned (or other payments earned, as applicable) towards the purchase of the already-delivered CellFX System, or the physician must return the CellFX System to the Company. As patient procedures and surveys are completed under the Controlled Launch, the Company accrues the value of the credits earned, which are recorded in accrued expenses on the balance sheet, with a corresponding charge to sales and marketing expense. During year ended December 31, 2021, the Company recorded $1.8 million of sales and marketing expense in relation to the Controlled Launch. During the year ended December 31, 2021, certain consultants completed the Controlled Launch and entered into purchase agreements with the Company, whereby they used their credits or other earned payments towards the purchase of a CellFX System. Accordingly, approximately $1.1 million of the accrued liability related to the Controlled Launch was relieved and recognized as revenue on a non-cash basis as a result of the purchase. See Note 9 for additional detail of revenue transactions.

Employee Benefit Plans (Narrative) (Details) - USD ($)	12 Months Ended
Employee Benefit Plans (Narrative) (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Employee Benefit Plans [Abstract]
Employer matching contributions	$ 0	$ 0	$ 0

- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

+ References + Details

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 28,614	$ 12,463
Investments		8,012
Accounts receivable	61
Inventory	5,824
Prepaid expenses and other current assets	2,131	1,864
Total current assets	36,630	22,339
Property and equipment, net	2,462	2,478
Intangible assets, net	3,216	3,882
Goodwill	2,791	2,791
Right-of-use assets	8,785	9,438
Other assets	365	365
Total assets	54,249	41,293
Current liabilities:
Accounts payable	2,904	1,717
Accrued expenses	4,389	5,326
Deferred revenue	16
Lease liability, current	774	542
Note payable, current	436
Total current liabilities	8,519	7,585
Lease liability, less current portion	10,040	10,814
Total liabilities	18,559	18,399
Commitments and contingencies (Note 13)
Stockholders' equity:
Preferred stock, $0.001 par value; authorized – 50,000 shares; no shares issued and outstanding
Common stock, $0.001 par value: authorized – 500,000 shares; issued and outstanding – 29,716 shares and 25,550 shares at December 31, 2021 and 2020, respectively	29	25
Additional paid-in-capital	271,861	195,410
Accumulated other comprehensive income (loss)		(1)
Accumulated deficit	(236,200)	(172,540)
Total stockholders' equity	35,690	22,894
Total liabilities and stockholders' equity	$ 54,249	$ 41,293

Summary Of Significant Accounting Policies (Tables)	12 Months Ended
Summary Of Significant Accounting Policies (Tables)	Dec. 31, 2021
Summary Of Significant Accounting Policies [Abstract]
Schedule Of Warranty Accrual Activity	Year Ended December 31, 2021 2020Beginning balance $ — $ — Add: Accruals for warranties issued during the period 80 — Less: Settlements made during the period — —Ending balance $ 80 $ —
Anti-Dilutive Shares Excluded From Computation Of Diluted Net Loss Per Share	Year Ended December 31, 2021 2020 2019Common stock warrants — 612,310 167,847Common stock options 5,996,813 5,039,194 3,749,186Restricted stock units — 111,305 222,606Total 5,996,813 5,762,809 4,139,639

Income Taxes (Tables)	12 Months Ended
Income Taxes (Tables)	Dec. 31, 2021
Income Taxes [Abstract]
Income (Loss) Before Income Taxes	Year Ended December 31, 2021 2020 2019Domestic $ (63,660) $ (49,851) $ (46,971)Foreign — — — $ (63,660) $ (49,851) $ (46,971)
Components of Income Tax Expense (Benefit)	December 31, 2021 2020 2019Current Federal $ — $ — $ —State 3 3 3Foreign — — —Total current 3 3 3 Deferred Federal — — —State — — —Foreign — — —Total deferred — — — Total provision for income taxes $ 3 $ 3 $ 3
Reconcilement Of Tax Rates	Year Ended December 31, 2021 2020 2019Federal tax at statutory rate 21.0% 21.0% 21.0%State tax (benefit) at statutory rate 8.4 8.4 (5.0) Research and development credits 1.9 2.1 2.0 Change in valuation allowance (26.8) (43.3) (18.0) Deferred adjustment — 8.5 — Change in tax rate — 4.2 — Uncertain Tax Position (2.3) — — Other (2.2) (0.8) — Provision for income taxes —% —% —%
Components Of Deferred Tax Assets	December 31, 2021 2020Deferred tax assets Accruals $ 1,034 $ 894Net operating loss carryforwards 49,246 36,531Tax credit carryforwards 6,611 5,431Stock-based compensation 12,188 9,391Lease liability under ASC 842 3,182 3,339Gross deferred tax assets 72,261 55,586Valuation allowance (69,006) (51,973)Total deferred tax assets 3,255 3,613 Deferred tax liabilities Intangibles (365) (486)ROU asset under ASC 842 (2,862) (3,096)Fixed assets (28) (31)Total deferred tax liabilities (3,255) (3,613) Net deferred tax assets/(liabilities) $ — $ —
Reconciliation Of Unrecognized Tax Benefit Accounts	December 31, 2021 2020 2019Unrecognized tax benefits at beginning of year $ 2,491 $ 1,470 $ 877Increases related to current year tax positions 2,649 1,021 593Unrecognized tax benefits at end of year $ 5,140 $ 2,491 $ 1,470

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Consolidated Balance Sheets [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	29,716,000	25,550,000
Common stock, shares outstanding	29,716,000	25,550,000

Stockholders' Equity And Stock-Based Compensation (Schedule Of Fair Value Of Employee Stock Options) (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	78.00%	70.00%	70.00%
Stock Options [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	5 years 3 months 18 days	5 years 3 months 18 days	4 months 24 days
Risk-free interest rate	0.90%	0.30%	1.40%
Stock Options [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	6 years 1 month 6 days	6 years 1 month 6 days
Risk-free interest rate	1.40%	0.50%	2.60%
2017 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	78.00%	70.00%	70.00%
2017 Employee Stock Purchase Plan [Member] \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	6 months	6 months	6 months
Risk-free interest rate	0.06%	0.10%	1.70%
2017 Employee Stock Purchase Plan [Member] \| Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term in years	1 year	1 year	1 year
Risk-free interest rate	0.10%	1.00%	2.60%

Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
Income Taxes (Narrative) (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Taxes [Line Items]
Income tax provision (benefit)
Increase in valuation allowance	17,000,000.0	21,600,000
Total unrecognized tax benefit	5,140,000	$ 2,491,000	$ 1,470,000	$ 877,000
Accrued interest or penalties	0
Federal And California [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 148,000,000.0
Net operating loss carryforward, expiration	2034
NOL, percent of taxable income	80.00%
Federal [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 173,700,000
Research and development credit carryforward	$ 5,300,000
Research and development tax credit carryforward, expiration	2035
California [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 163,400,000
Research and development credit carryforward	$ 5,000,000.0

Income Taxes (Reconcilement Of Tax Rates) (Details)	12 Months Ended
Income Taxes (Reconcilement Of Tax Rates) (Details)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Abstract]
Federal tax at statutory rate	21.00%	21.00%	21.00%
State tax (benefit) at statutory rate	8.40%	8.40%	(5.00%)
Research and development credits	1.90%	2.10%	2.00%
Change in valuation allowance	(26.80%)	(43.30%)	(18.00%)
Deferred adjustment		8.50%
Change in tax rate		4.20%
Uncertain tax position	(2.30%)
Other	(2.20%)	(0.80%)
Provision for income taxes

Consolidated Statements Of Operations And Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues:
Revenues	$ 1,418
Cost and expenses:
Cost of revenues	1,968
Research and development	28,640	26,444	24,961
Sales and marketing	14,751	7,256	5,857
General and administrative	19,073	16,265	17,136
Total costs and expenses	64,432	49,965	47,954
Loss from operations	(63,014)	(49,965)	(47,954)
Other income (expense):
Interest income (expense), net	(646)	114	983
Total other income (expense)	(646)	114	983
Loss from operations, before income taxes	(63,660)	(49,851)	(46,971)
Income tax benefit
Net loss	(63,660)	(49,851)	(46,971)
Other comprehensive gain (loss):
Unrealized gain (loss) on available-for-sale securities	1	(5)	5
Comprehensive loss	$ (63,659)	$ (49,856)	$ (46,966)
Net loss per share:
Basic and diluted net loss per share	$ (2.28)	$ (2.14)	$ (2.26)
Weighted average shares used to compute net loss per common share - basic and diluted	27,964	23,248	20,746

Commitments And Contingencies (Narrative) (Details) $ / shares in Units, $ in Millions		1 Months Ended				12 Months Ended
	May 13, 2021 USD ($)	Jun. 30, 2021 USD ($) $ / shares	May 31, 2020 USD ($)	Nov. 30, 2019 USD ($)	Jan. 31, 2019 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Mar. 11, 2021 USD ($)	May 31, 2019 ft²	Jan. 31, 2017 ft²
Commitments and Contingencies [Line Items]
Director and officer insurance premium payable	$ 2.6
Insurance down payment	0.7
Financed insurance policy balance	$ 1.9
Financed insurance policy interest rate	3.69%
Lease term											5 years
Area Of Lease \| ft²											15,700
Rent expense, including common area maintenance charges						$ 1.9	$ 1.7	$ 0.5
Robert W. Duggan [Member] \| Private Placement [Member]
Commitments and Contingencies [Line Items]
Principal sum		$ 41.0
Accrued interest		$ 0.6
Price per share \| $ / shares		$ 16.40
Lease Amendment - Phase One [Member]
Commitments and Contingencies [Line Items]
Area Of Lease \| ft²										13,300
Lease Amendment - Phase Two [Member]
Commitments and Contingencies [Line Items]
Area Of Lease \| ft²										21,300
Accounting Standards Update 2016-02 [Member]
Commitments and Contingencies [Line Items]
Increase in right-of-use assets			$ 4.8	$ 3.0	$ 2.0	8.8
Increase in lease liability						10.8
Loan Agreement [Member] \| Robert W. Duggan [Member]
Commitments and Contingencies [Line Items]
Principal sum									$ 41.0
Debt instrument, stated interest rate									5.00%
Interest expense						$ 0.6

Employee Benefit Plans	12 Months Ended
Employee Benefit Plans	Dec. 31, 2021
Employee Benefit Plans [Abstract]
Employee Benefit Plans	14. Employee Benefit Plans The Company sponsors a defined contribution plan under which it may make discretionary contributions. The Company did not make any employer matching contributions to this plan during the years ended December 31, 2021, 2020 and 2019.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section S99
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=21916913&loc=d3e273930-122802

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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+ Details

Stockholders' Equity And Stock-Based Compensation (Summary Of Time-Based Stock Option Activity) (Details) - Time-Based Options [Member] - 2015, 2017 And Inducement Plans [Member] - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	4,055,352
Options granted, Number of shares	1,023,333
Options exercised, Number of shares	(53,731)
Options canceled, Number of shares	(162,975)
Options expired/Redeemed, Number of shares	(65,263)
Ending Balance, Number of shares	4,796,716	4,055,352
Exercisable, Number of shares	3,018,902
Beginning Balance, Weighted average exercise price per share	$ 15.04
Options granted, Weighted average exercise price per share	22.04
Options exercised, Weighted average exercise price per share	11.47
Options canceled, Weighted average exercise price per share	16.94
Options expired, Weighted average exercise price per share	19.92
Ending Balance, Weighted average exercise price per share	16.44	$ 15.04
Exercisable, Weighted average exercise price per share	$ 16.38
Weighted average remaining life	7 years 18 days	6 years 4 months 13 days
Weighted average remaining life, exercisable	6 years 18 days

Balance Sheet Components (Schedule Of Amortization Of Intangible Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Balance Sheet Components [Abstract]
2022	$ 665
2023	665
2024	665
2025	665
2026	556
Intangible assets, net	$ 3,216	$ 3,882

Balance Sheet Components	12 Months Ended
Balance Sheet Components	Dec. 31, 2021
Balance Sheet Components [Abstract]
Balance Sheet Components	4. Balance Sheet Components InventoryInventory consisted of the following (in thousands): Year Ended December 31, 2021 2020Raw materials $ 2,010 $ —Work in process 1,371 —Finished goods 2,443 — Total inventory $ 5,824 $ — Property and Equipment, net Property and equipment, net consisted of the following (in thousands): December 31, 2021 2020Leasehold improvements $ 2,519 $ 2,805Laboratory equipment 1,019 878Furniture, fixtures and equipment 932 517Software 202 128Construction in progress 186 66 4,858 4,394Less: Accumulated depreciation and amortization (2,396) (1,916) $ 2,462 $ 2,478 The lease for the Company’s current premises in Hayward, California began in July 2017, per terms of the lease, the landlord provided $2.1 million in tenant improvement allowance which was capitalized. Depreciation expense for the years ended December 31, 2021, 2020, and 2019 was $0.5 million, $0.4 million, and $0.5 million, respectively. Intangible Assets, net Intangible assets primarily consist of a license to utilize certain patents, know-how and technology relating to the Company’s NPS for biomedical applications acquired from Old Dominion University Research Foundation (ODURF), Eastern Virginia Medical School (EVMS), and the University of Southern California. In addition, the Company entered into a sponsored research agreement (“SRA”) with Old Dominion University’s Frank Reidy Research Center for Bioelectrics, a leading research organization in the field, which includes certain intellectual property rights arising from the research. The Company is amortizing the intangible assets over an estimated useful life of 12 years. Intangible assets, net consisted of the following (in thousands): December 31, 2021 2020Acquired patents and licenses $ 7,985 $ 7,985Less: Accumulated amortization (4,769) (4,103) $ 3,216 $ 3,882 A schedule of the amortization of intangible assets is as follows (in thousands): Years ending December 31: 2022 $ 6652023 6652024 6652025 6652026 556 $ 3,216 Accrued Expenses Accrued expenses consisted of the following (in thousands): December 31, 2021 2020Compensation expense $ 2,932 $ 3,324Controlled launch (Note 8) 534 —Director and officer liability insurance (Note 12) — 1,563Clinical trial fees and costs 245 188Professional fees 85 87Warranty 80 —Other 513 164 $ 4,389 $ 5,326

Controlled Launch (Narrative) (Details) $ in Millions	12 Months Ended
Controlled Launch (Narrative) (Details) $ in Millions	Dec. 31, 2021 USD ($) item
Number of KOLs \| item	70
Program expenses	$ 1.8
Revenue recognized	$ 1.1
Minimum [Member]
Number of patients participating in procedure	40
Maximum [Member]
Number of patients participating in procedure	50

Income Taxes (Income (Loss) Before Income Taxes) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Abstract]
Domestic	$ (63,660)	$ (49,851)	$ (46,971)
Loss from operations, before income taxes	$ (63,660)	$ (49,851)	$ (46,971)

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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+ Details

Segment Reporting	12 Months Ended
Segment Reporting	Dec. 31, 2021
Segment Reporting [Abstract]
Segment Reporting	10. Segment Reporting The Company operates and manages the business as one reportable and operating segment. The Company’s Chief Executive Officer and Chief Financial Officer act as the chief operating decision makers (“CODM”) of the Company. The CODM reviews the results of the Company on a consolidated basis, however in making certain operating decisions and assessing performance, the CODM will additionally review the disaggregated revenue results by product and geography. All of the Company’s long-lived assets are based in the United States.Revenue by product consisted of the following (in thousands): Year Ended December 31, 2021 2020 2019Systems $ 1,189 $ — $ —Cycle units 229 — —Total consolidated revenue $ 1,418 $ — $ —Revenue by geography consisted of the following (in thousands): Year Ended December 31, 2021 2020 2019North America $ 1,182 $ — $ —Rest of World 236 — —Total consolidated revenue $ 1,418 $ — $ —

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Stockholders' Equity And Stock-Based Compensation (Narrative) (Details)						1 Months Ended				12 Months Ended
	Jun. 30, 2021 USD ($) $ / shares shares	Feb. 05, 2021 $ / shares shares	Feb. 04, 2021 USD ($) shares	Jan. 01, 2021 shares	Jan. 01, 2020 shares	Jul. 31, 2021 USD ($)	May 31, 2021 shares	Mar. 31, 2021 shares	Jun. 30, 2020 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Dec. 31, 2017 shares	Dec. 31, 2014 $ / shares shares	Nov. 30, 2017 shares
Stockholders' Equity [Line Items]
Preferred stock, shares authorized										50,000,000	50,000,000
Preferred stock, par value \| $ / shares										$ 0.001	$ 0.001
Preferred stock, shares outstanding										0	0	0
Common stock, par value \| $ / shares										$ 0.001	$ 0.001
Common stock, shares authorized										500,000,000	500,000,000
Proceeds from issuance of common stock \| $										$ 56,697,000	$ 29,434,000
Exercise price of warrants/rights \| $ / shares											$ 7.01
Common stock, shares issued										29,716,000	25,550,000
Reduction to APIC from shares withheld for tax \| $												$ (613,000)
Total stock-based compensation expense \| $										$ 14,601,000	$ 10,075,000	11,287,000
Unrecognized compensation cost \| $										$ 15,800,000
Weighted average remaining contractual life										2 years 8 months 12 days
2017 Employee Stock Purchase Plan [Member]
Stockholders' Equity [Line Items]
Common stock, shares issued										91,378	82,971
Shares authorized											250,000
Additional common stock reserved for issuance										383,250
Increase in shares available for issuance threshold of common stock outstanding, number of shares											450,000
Increase in shares available for issuance threshold of common stock outstanding, percent outstanding											1.50%
Shares available for grant										649,096
2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Term period										10 years	10 years
Shares authorized															1,000,000
2017 Plan [Member]
Stockholders' Equity [Line Items]
Term period											10 years
Shares authorized											1,500,000
Additional common stock reserved for issuance				1,022,002	833,018
Increase in shares available for issuance threshold of common stock outstanding, number of shares											1,200,000
Increase in shares available for issuance threshold of common stock outstanding, percent outstanding											4.00%
Shares available for grant										443,196
Rights Offering [Member]
Stockholders' Equity [Line Items]
Common stock, par value \| $ / shares									$ 0.001
Value of warrants/rights \| $									$ 30,000,000.0
Warrants/rights outstanding									641,571	0
Exercise price of warrants/rights \| $ / shares									$ 7.01
Net proceeds \| $			$ 4,500,000						$ 29,400,000
Number of common shares called by issuance of warrants									4,279,600
Number of warrants to purchase shares of common stock									0.15
Period of time warrant not able to be redeemed										6 months
Period the warrants are exercisable after issuance										30 days
Percentage requirement for warrant redemption									200.00%
Redemption per warrant \| $ / shares		$ 0.01							$ 0.01
Period of time required for redemption of warrants										10 days
Warrants exercised		5,139	636,432
First Vesting Portion [Member] \| 2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Vesting percentage											25.00%
General And Administrative [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense \| $										$ 6,512,000	$ 4,875,000	6,583,000
Research And Development [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense \| $										5,211,000	4,013,000	3,821,000
Stock Options [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense \| $										4,100,000
Stock Options [Member] \| 2017 Plan [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense \| $										$ 1,400,000
Stock Options [Member] \| 2015, 2017 And Inducement Plans [Member]
Stockholders' Equity [Line Items]
Warrants exercised										53,731
Restricted Stock Units [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense \| $											86,000
Unrecognized compensation cost \| $										$ 0
Restricted Stock Units [Member] \| Granted In 2017 [Member]
Stockholders' Equity [Line Items]
Units granted during period													160,974
Total stock-based compensation expense \| $										0	0	0
Unrecognized compensation cost \| $										$ 0
Units outstanding										0
Common Stock Warrants [Member]
Stockholders' Equity [Line Items]
Warrants exercised										585,069
Time-Based Options [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense \| $										$ 9,235,000	8,739,000	10,895,000
Time-Based Options [Member] \| 2015, 2017 And Inducement Plans [Member]
Stockholders' Equity [Line Items]
Warrants exercised										53,731
Total intrinsic value of options exercised \| $										$ 800,000	1,600,000	1,000,000.0
Fair value of options granted \| $										$ 15,100,000	6,700,000	8,400,000
Time-Based Options [Member] \| Tranche One Through Four [Member]
Stockholders' Equity [Line Items]
Vesting percentage										25.00%
Performance Shares [Member]
Stockholders' Equity [Line Items]
Total stock-based compensation expense \| $										$ 4,840,000	133,000	100,000
Performance Shares [Member] \| 2017 And Inducement Plans [Member]
Stockholders' Equity [Line Items]
Fair value of options granted \| $										2,500,000	$ 5,500,000	400,000
Private Placement [Member]
Stockholders' Equity [Line Items]
Common stock, par value \| $ / shares														$ 0.001
Chairman, Robert W. Duggan [Member] \| Rights Offering [Member]
Stockholders' Equity [Line Items]
Number of warrants to purchase shares of common stock									2,561,873
Chairman, Robert W. Duggan [Member] \| Private Placement [Member]
Stockholders' Equity [Line Items]
Common stock, par value \| $ / shares	$ 0.001
Shares sold	3,048,780
Price per share \| $ / shares	$ 16.40
Aggregate issuance costs \| $	$ 41,000,000.0
Proceeds from issuance of common stock \| $	8,400,000					$ 8,400,000
Net proceeds \| $	$ 50,000,000.0
Common stock, shares issued	3,048,780
Certain Employees [Member] \| Restricted Stock Units [Member] \| Granted In 2017 [Member]
Stockholders' Equity [Line Items]
Shares available for grant											68,800
Total stock-based compensation expense \| $										$ 100,000	$ 300,000	$ 400,000
Certain Employees [Member] \| Restricted Stock Units [Member] \| First Vesting Portion [Member] \| Granted In 2017 [Member]
Stockholders' Equity [Line Items]
Vesting percentage											50.00%
Cliff vest date										Jun. 01, 2019
Certain Employees [Member] \| Restricted Stock Units [Member] \| Second Vesting Portion [Member]
Stockholders' Equity [Line Items]
Cliff vest date										Jun. 01, 2021
Certain Employees [Member] \| Restricted Stock Units [Member] \| Second Vesting Portion [Member] \| Granted In 2017 [Member]
Stockholders' Equity [Line Items]
Vesting percentage											50.00%
Common Stock
Stockholders' Equity [Line Items]
Shares issued										288,000
Warrants exercised										54,000	175,000	99,000
Common Stock \| 2017 Employee Stock Purchase Plan [Member]
Stockholders' Equity [Line Items]
Additional common stock reserved for issuance							1,000,000
Common Stock \| 2017 Inducement Equity Incentive Plan [Member]
Stockholders' Equity [Line Items]
Shares authorized										1,044,513
Robert W. Duggan [Member] \| Private Placement [Member]
Stockholders' Equity [Line Items]
Price per share \| $ / shares	$ 16.40
MDB Capital Group, LLC [Member] \| Initial Public Offering [Member]
Stockholders' Equity [Line Items]
Warrants/rights outstanding										0
Number of common shares called by issuance of warrants												574,985
Price per share \| $ / shares												$ 5.00
Common stock received from rights/warrants exercised								68,958
Warrants exercised								85,385
Exercisable period of warrants or rights										5 years
MDB Capital Group, LLC [Member] \| Private Placement [Member]
Stockholders' Equity [Line Items]
Number of common shares called by issuance of warrants														299,625
Price per share \| $ / shares														$ 2.67
Common stock received from rights/warrants exercised								40,563
Warrants exercised								45,638
Exercisable period of warrants or rights														7 years
Stifel, Nicolaus & Company Inc. [Member] \| At the Market Offering [Member]
Stockholders' Equity [Line Items]
Value of warrants/rights \| $			$ 60,000,000.0
Warrants/rights outstanding										288,490
Exercise price of warrants/rights \| $ / shares										$ 27.73
Net proceeds \| $										$ 7,400,000

Summary Of Significant Accounting Policies (Schedule Of Warranty Accrual Activity) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)
Summary Of Significant Accounting Policies [Abstract]
Beginning balance
Add: Accruals for warranties issued during the period	80
Less: Settlements made during the period
Ending balance	$ 80

Investments And Fair Value Of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2021
Investments And Fair Value Of Financial Instruments [Abstract]
Schedule Of Available-For-Sale Securities	December 31, 2020 Cost Gross Unrealized Gains Gross Unrealized Losses Fair ValueU.S. Treasury securities $ 8,013 $— $ (1) $ 8,012Total assets measured at fair value $ 8,013 $— $— $ 8,012
Schedule Of Contractual Maturities Of Investments	December 31, 2021 2020Due in one year $ — $ 8,012Due in one to two years — —Total $ — $ 8,012
Fair Value Of Financial Assets Measured On A Recurring Basis	December 31, 2021 Assets Classification Level 1 Level 2 Level 3 Total Money market funds Cash and cash equivalents $ 23,675 $— $— $ 23,675 Total assets measured at fair value $ 23,675 $ - $— $ 23,675 December 31, 2020Assets Classification Level 1 Level 2 Level 3 Total Money market funds Cash and cash equivalents $ 7,176 $— $— $ 7,176 U.S. Treasury securities Cash and cash equivalents — 2,004 — 2,004 U.S. Treasury securities Investments — 8,012 — 8,012 Total assets measured at fair value $ 7,176 $ 10,016 $— $ 17,192

Goodwill (Narrative) (Details) - USD ($)	12 Months Ended
Goodwill (Narrative) (Details) - USD ($)	Dec. 31, 2021	Dec. 31, 2014	Dec. 31, 2020
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Aggregate consideration		$ 5,500,000
Goodwill	$ 2,791,000	$ 2,800,000	$ 2,791,000
Goodwill impairment	$ 0

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock Option Activity) (Details) - Stock Options [Member] - 2015, 2017 And Inducement Plans [Member] - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Beginning Balance, Number of shares	5,039,194
Options granted, Number of shares	1,239,588
Options exercised, Number of shares	(53,731)
Options canceled, Number of shares	(162,975)
Options expired/Redeemed, Number of shares	(65,263)
Ending Balance, Number of shares	5,996,813	5,039,194
Exercisable, Number of shares	3,312,074
Beginning Balance, Weighted average exercise price per share	$ 14.26
Options granted, Weighted average exercise price per share	22.10
Options exercised, Weighted average exercise price per share	11.47
Options canceled, Weighted average exercise price per share	16.94
Options expired, Weighted average exercise price per share	19.92
Ending Balance, Weighted average exercise price per share	15.77	$ 14.26
Exercisable, Weighted average exercise price per share	$ 15.96
Weighted average remaining life	7 years 3 months 29 days	7 years 9 months 29 days
Weighted average remaining life, exercisable	6 years 2 months 23 days

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock-Based Compensation Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Total stock-based compensation expense	$ 14,601	$ 10,075	$ 11,287
Cost Of Revenues [Member]
Total stock-based compensation expense	129
Research And Development [Member]
Total stock-based compensation expense	5,211	4,013	3,821
Sales And Marketing [Member]
Total stock-based compensation expense	2,749	1,187	883
General And Administrative [Member]
Total stock-based compensation expense	$ 6,512	$ 4,875	$ 6,583

Commitments And Contingencies (Tables)	12 Months Ended
Commitments And Contingencies (Tables)	Dec. 31, 2021
Commitments And Contingencies [Abstract]
Schedule Of Information Related To Right-Of-Use Assets And Lease Liabilities	Year ending December 31: 2022$ 1,8062023 1,8452024 1,9102025 1,9772026 2,046Thereafter 6,191Total lease payments 15,775Less imputed interest (4,961)Total lease liabilities$ 10,814 Other supplemental information: Cash paid for operating lease liabilities$ 1,643 Current operating lease liabilities 774Non-current operating lease liabilities 10,040Total lease liabilities$ 10,814 Weighted-average remaining lease term 7.83Weighted-average discount rate 10%

Balance Sheet Components (Schedule Of Property And Equipment, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,858	$ 4,394
Less: Accumulated depreciation	(2,396)	(1,916)
Property and equipment, net	2,462	2,478
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	2,519	2,805
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	1,019	878
Furniture, Fixtures, And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	932	517
Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	202	128
Construction In Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 186	$ 66

Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	Total
Balance at Dec. 31, 2018	$ 21	$ 142,032	$ (1)	$ (75,718)	$ 66,334
Balance, shares at Dec. 31, 2018	20,593
Issuance of shares upon exercise of warrants, shares	37
Issuance of shares upon exercise of stock options		272			272
Issuance of shares upon exercise of stock options, shares	99
Issuance of shares under employee stock purchase plan		423			423
Issuance of shares under employee stock purchase plan, shares	38
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares	58
Stock-based compensation expense		11,287			11,287
Tax payments related to shares withheld for vested restricted stock units		(613)			(613)
Unrealized gain on available-for-sale securities			5		5
Net loss				(46,971)	(46,971)
Balance at Dec. 31, 2019	$ 21	153,401	4	(122,689)	30,737
Balance, shares at Dec. 31, 2019	20,825
Issuance of shares upon exercise of warrants		1,127			1,127
Issuance of shares upon exercise of warrants, shares	187
Issuance of shares upon exercise of stock options		887			887
Issuance of shares upon exercise of stock options, shares	175
Issuance of shares under employee stock purchase plan		490			490
Issuance of shares under employee stock purchase plan, shares	83
Issuance of common stock and warrants in connection with rights offering at $7.01 per unit, net of issuance cost of $565	$ 4	29,430			29,434
Issuance of common stock and warrants in connection with rights offering at $7.01 per unit, net of issuance cost of $565, shares	4,280
Stock-based compensation expense		10,075			10,075
Unrealized gain on available-for-sale securities			(5)		(5)
Net loss				(49,851)	(49,851)
Balance at Dec. 31, 2020	$ 25	195,410	(1)	(172,540)	$ 22,894
Balance, shares at Dec. 31, 2020	25,550				25,550
Issuance of common stock as part of debt extinguishment and private investment, net of issuance cost of $106	$ 3	49,891			$ 49,894
Issuance of common stock as part of debt extinguishment and private investment, net of issuance cost of $106, shares	3,049
Issuance of shares upon exercise of warrants	$ 1	3,333			3,334
Issuance of shares upon exercise of warrants, shares	585
Issuance of shares upon exercise of stock options		616			616
Issuance of shares upon exercise of stock options, shares	54
Issuance of common stock as part of ATM offering, net of issuance cost of $568		7,432			7,432
Issuance of common stock as part of ATM offering net of issuance cost of $568, shares	288
Issuance of shares under employee stock purchase plan		810			810
Issuance of shares under employee stock purchase plan, shares	91
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes		(232)			(232)
Issuance of common stock upon vesting of restricted stock units, net of shares withheld for employee taxes, shares	99
Stock-based compensation expense		14,601			14,601
Unrealized gain on available-for-sale securities			$ 1		1
Net loss				(63,660)	(63,660)
Balance at Dec. 31, 2021	$ 29	$ 271,861		$ (236,200)	$ 35,690
Balance, shares at Dec. 31, 2021	29,716				29,716

Revenue	12 Months Ended
Revenue	Dec. 31, 2021
Revenue [Abstract]
Revenue	9. Revenue The Company recognizes revenue at a point in time when it satisfies performance obligations by transferring control of promised goods to its customers. The amount of revenue recognized is equal to the consideration which the Company is entitled to in exchange for the promised goods, excluding any amounts assessed by government authorities for taxes which might be collected from a customer. This consideration may include non-cash services performed, as is the case with revenue recognized in connection with the Controlled Launch. Total revenue recognized for the year ended December 31, 2021 was $1.4 million, of which approximately $1.1 million was driven by the redemption of non-cash credits earned as part of the Controlled Launch, with the balance of approximately $0.3 million driven by cash purchases of cycle units (“CUs”) and the first two CellFX commercial consoles sold. Sales contracts often involve the sale and delivery of multiple performance obligations in the contract. Performance ObligationsSystems consist of the CellFX console and its embedded software, handpieces, and disposable tips. The console is a physical piece of hardware used by the customer to perform patient procedures. Individually the console and software are not distinct, therefore the Company combines the console and embedded software to form one distinct system performance obligation. Payment for systems is generally due prior to shipment, and the system performance obligation is satisfied upon shipment of the system to the customer. Handpieces are attached to the console and used in conjunction with tips to perform patient procedures. Generally, upon initial sale of a system to a customer, the Company will include two handpieces. The handpiece has a shorter expected useful life than the console, and a customer can purchase additional handpieces when needed, as they are available for sale on a stand-alone basis. Payment for handpieces is generally due prior to shipment, and handpieces represent a distinct performance obligation which is satisfied either upon shipment, or upon delivery of the handpiece to the customer, depending on the specific contract.Tips are single-patient multiple-use products that come in different sizes, each of which are to be used for specific procedures. Tips are attached to the handpiece for use in patient procedures and, upon detachment from the handpiece, a tip cannot be reused, and it must be disposed of. Tips are available for sale on a stand-alone basis and payment is generally due prior to shipment. Tips represent a distinct performance obligation which is satisfied either upon shipment, or upon delivery of the tips to the customer, depending on the specific contract.CUs are credits that authorize the customer to perform a procedure, or cycle. Each procedure requires a specific number of CUs, dependent upon type of tip used and procedure level selected. As the procedure is performed, the applicable number of CUs are decremented. When the customer’s balance of CUs on a specific system is depleted, the system will no longer function until the customer purchases additional CUs. Customers can purchase additional CUs via the Company’s CellFX Marketplace which is an online marketplace accessible directly from the CellFX System. Payment for CUs is due upon order placement and the CUs are immediately available for download to the console via CellFX CloudConnect. CUs represent a distinct performance obligation which is satisfied upon delivery of the CUs to CellFX CloudConnect.Shipping and handling activities are not considered to be a separate performance obligation. The Company’s standard commercial agreements generally include FOB shipping point terms. The Company has made an accounting policy election to account for shipping and handling costs as fulfillment costs because the shipping and handling activities occur after the customer obtains control of the product. Transaction PriceWhen there are multiple performance obligations present, the total transaction price shall be allocated to each of the performance obligations based upon the relative SSPs of those performance obligations. The Company establishes SSPs based on multiple factors including, prices charged by the Company for similar offerings, product-specific business objectives, and the estimated cost to provide the performance obligation. However, upon the sale of a new CellFX System, all performance obligations are delivered concurrently and therefore there is no impact to revenue recognition timing, and the Company has determined allocations are not necessary. Should the customer purchase additional CUs, handpieces, or tips at a later time, those purchases will be made under separate purchase agreements, generally containing only one performance obligation each, therefore no price allocation is necessary in that scenario either. The Company evaluates the possible impact of variable consideration in determining the transaction price, in particular the possibility of future returns or credits. Sales agreements allow for a right of return only if the product does not conform to the agreed upon quality standards or if the product was shipped due to Company error. The Company anticipates such returns will be minimal and has made no adjustments to the transaction price for any estimated returns.The Company has made an accounting policy election to exclude from the measurement of the transaction price all taxes which are imposed on and concurrent with a specific revenue-producing transaction and collected by the entity from a customer. Controlled Launch AgreementsIn August 2021 the Company began to recognize revenue in relation to the conversion of Controlled Launch Program participants into sales agreements (Note 8). These customers were already in possession of the system, handpiece, and tips. As such, upon execution of these purchase agreements, the Company recognized revenue on the agreements because control of all performance obligations were transferred at that time. These customers separately purchased CUs in order to operate the CellFX System and the revenue for these CUs was recognized upon delivery of the CUs to CellFX CloudConnect.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI http://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130554-203045

+ Details

Stockholders' Equity And Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Stockholders' Equity [Line Items]
Summary Of Stock Warrant Activity	Weighted Average Weighted Remaining Number of Average Contractual Shares Exercise Price Life (in Years)Warrants outstanding at December 31, 2020 612,310 $ 6.40 0.26 Issued — — Exercised (585,069) 6.47 Expired/Redeemed (27,241) 3.56 Warrants outstanding and exercisable at December 31, 2021 — $ — —
Summary Of Stock-Based Compensation Expense	Year Ended December 31, 2021 2020 2019Cost of revenues $ 129 $ — $ —Research and development 5,211 4,013 3,821Sales and marketing 2,749 1,187 883General and administrative 6,512 4,875 6,583Total stock-based compensation expense $ 14,601 $ 10,075 $ 11,287
Summary Of Stock-Based Compensation Expense By Type	Year Ended December 31, 2021 2020 2019Time-based options $ 9,235 $ 8,739 $ 10,895Performance options 4,840 133 100RSU — 86 —ESPP 526 1,117 292Total stock-based compensation expense $ 14,601 $ 10,075 $ 11,287
Time-Based Options [Member]
Stockholders' Equity [Line Items]
Summary Of Stock Option Activity	Stock Options Outstanding Number ‎of shares Weighted‎average‎exercise price Weighted‎average‎remaining life‎(in years)Balances — December 31, 2020 4,055,352 $15.04 6.37 Options granted 1,023,333 22.04 Options exercised (53,731) 11.47 Options canceled (162,975) 16.94 Options expired (65,263) 19.92 Balances — December 31, 2021 4,796,716 $16.44 7.05 Exercisable — December 31, 2021 3,018,902 $16.38 6.05
Performance Shares [Member]
Stockholders' Equity [Line Items]
Summary Of Stock Option Activity	Stock Options Outstanding Number ‎of shares Weighted‎average‎exercise price Weighted‎average‎remaining life‎(in years)Balances — December 31, 2020 983,842 $11.06 8.25 Options granted 216,255 22.41 Options exercised — — Options canceled — — Options expired — — Balances — December 31, 2021 1,200,097 $13.11 8.44 Exercisable — December 31, 2021 293,172 $11.64 8.08
Stock Options [Member]
Stockholders' Equity [Line Items]
Summary Of Stock Option Activity	Weighted Weighted Average Average Remaining Number of Exercise Contractual Shares Price Life (in Years)Balances - December 31, 2020 5,039,194 $ 14.26 7.83 Options granted 1,239,588 22.10 Options exercised (53,731) 11.47 Options canceled (162,975) 16.94 Options expired (65,263) 19.92 Balances - December 31, 2021 5,996,813 $ 15.77 7.33Stock options exercisable at December 31, 2021 3,312,074 $ 15.96 6.23
Schedule Of Fair Value Of Employee Stock Options	Year Ended December 31, 2021 2020 2019Expected term in years 5.3 - 6.1 5.3 - 6.1 0.4 - 6.1Expected volatility 78% 70% 70%Risk-free interest rate 0.9 - 1.4% 0.3 - 0.5% 1.4 - 2.6%Dividend yield — — —
2017 Employee Stock Purchase Plan [Member]
Stockholders' Equity [Line Items]
Schedule Of Fair Value Of Employee Stock Options	Year Ended December 31, 2021 2020 2019Expected term in years 0.5 - 1.0 0.5 - 1.0 0.5 - 1.0Expected volatility 78% 70% 70%Risk-free interest rate 0.06% - 0.1% 0.1% - 1.0% 1.7% - 2.6%Dividend yield — — —

Balance Sheet Components (Schedule Of Accrued Expenses) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Balance Sheet Components [Abstract]
Compensation expense	$ 2,932	$ 3,324
Controlled launch (Note 8)	534
Director and officer liability insurance (Note 12)		1,563
Clinical trial fees and costs	245	188
Professional fees	85	87
Warranty	80
Other	513	164
Accrued expenses	$ 4,389	$ 5,326

Commitments And Contingencies	12 Months Ended
Commitments And Contingencies	Dec. 31, 2021
Commitments And Contingencies [Abstract]
Commitments And Contingencies	13. Commitments and Contingencies Loan AgreementOn March 11, 2021, the Company and Robert W. Duggan, the Board Chairman, entered into a Loan Agreement in connection with Mr. Duggan lending the principal sum of $41.0 million to the Company. The Loan Agreement bore interest at a rate per annum equal to 5.0%, payable quarterly commencing on July 1, 2021. During the year ended December 31, 2021, the Company recorded $0.6 million of interest expense in relation to this Loan Agreement. In June 2021, the Loan Agreement was terminated and $41.0 million principal, together with approximately $0.6 million of accrued and unpaid interest, was fully settled via issuance of the Company’s common stock at a price per share of $16.40. Refer to Note 6 for additional details of the private placement sale. Insurance Loan AgreementOn May 13, 2021, the Company secured its annual director and officer liability insurance policy. The total premiums for the policy are approximately $2.6 million, of which the Company made a down payment of $0.7 million and financed the balance of $1.9 million via an Insurance Loan Agreement. The Insurance Loan Agreement has an annual interest rate of 3.69% and requires monthly payments through February 2022, upon which the Insurance Loan Agreement will be paid in full. The outstanding principal portion of the Insurance Loan Agreement, together with any accrued and unpaid interest, is recorded as a note payable in the balance sheet. Operating Leases In January 2017, the Company entered into a five-year lease (the “Existing Lease”) for approximately 15,700 square feet for its corporate headquarters located in Hayward, California. The lease commenced during July 2017. In May 2019, the Company entered into Lease Amendment 1 (the “Lease Amendment”) in relation to the Existing Lease and added the lease of new premises of approximately 13,300 square feet and 21,300 square feet, (“Expansion Premises 1” and “Expansion Premises 2”, respectively). Additionally, the term of the Existing Lease was extended to October 2029 to be coterminous with Expansion Premises 1 and Expansion Premises 2. The Company evaluated the lease amendment under the provisions of ASC 842. It concluded that the Lease Amendment would be accounted for as a single contract with the Existing Lease because the additional lease payments due to the Lease Amendment was not commensurate with the right-of-use asset granted to the Company. Though the Lease Amendment was accounted for as a single contract, the Existing Premises, Expansion Premises 1 (occupied in November 2019) and Expansion Premises 2 (occupied in May 2020) are accounted for as separate lease components. Accordingly, the Company measured and allocated consideration to each lease component as of the modification date. Upon commencement of each lease component, the Company reassessed and calculated the lease liability and right-of-use asset for the respective component. As a result, at the modification date, the Company remeasured its existing lease liability and recorded an additional right-of-use asset and lease liability of $2.0 million. The Company also recorded an additional right-of-use asset and lease liability of $3.0 million and $4.8 million at the commencement of Expansion Premises 1 in November 2019 and Expansion Premises 2 in May 2020, respectively. At December 31, 2021, total right-of-use assets and lease lability was approximately $8.8 million and $10.8 million, respectively. During the years ended December 31, 2021, 2020 and 2019, rent expense, including common area maintenance charges, was $1.9 million, $1.7 million and $0.5 million, respectively. Information related to the Company’s right-of-use assets and related lease liabilities were as follows (in thousands except for remaining lease term and discount rate): Year ending December 31: 2022$ 1,8062023 1,8452024 1,9102025 1,9772026 2,046Thereafter 6,191Total lease payments 15,775Less imputed interest (4,961)Total lease liabilities$ 10,814 Other supplemental information: Cash paid for operating lease liabilities$ 1,643 Current operating lease liabilities 774Non-current operating lease liabilities 10,040Total lease liabilities$ 10,814 Weighted-average remaining lease term 7.83Weighted-average discount rate 10%Legal Proceedings The Company maintains indemnification agreements with its directors and officers that may require the Company to indemnify them against liabilities that arise by reason of their status or service as directors or officers, except as prohibited by applicable law. From time to time, the Company may be involved in a variety of claims, lawsuits, investigations, and proceedings relating to securities laws, corporate governance, product liability and promotion, patent infringement, contract disputes, employment disputes, and other matters relating to various claims that arise in the normal course of the Company’s business, such as demands to inspect Company records and correspondence from the SEC and other government officials. The Company currently believes that these ordinary course matters are not material to the consolidated financial statements of the business; however, the results of litigation and claims are inherently unpredictable. In February 2022, a civil securities lawsuit was filed in the U.S. District Court for the Northern District of California against the Company and certain of its executive officers, following the Company’s announcement on February 8, 2022 that it had received an Additional Information letter from the FDA indicating that the FDA did not believe the Company provided sufficient clinical evidence to support its 510(k) submission to add the treatment of sebaceous hyperplasia to the CellFX System’s current U.S. labeling, and the subsequent decline of the market price of the Company’s common stock. The Company is currently evaluating the case and its allegations. The lawsuit seeks class certification, unspecified damages, fees, costs, and expenses. The Company expects to file a motion to dismiss the case later this year, and an estimate of possible loss or range of loss, if any, cannot be made.

Investments And Fair Value Of Financial Instruments (Fair Value Of Financial Assets Measured On A Recurring Basis) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
ASSETS
Total assets measured at fair value	$ 23,675	$ 17,192
Cash and cash equivalents [Member] \| Cash and money market funds [Member]
ASSETS
Total cash and cash equivalents	23,675	7,176
Cash and cash equivalents [Member] \| U.S. government and agency securities [Member]
ASSETS
Total cash and cash equivalents		2,004
Investments [Member]
ASSETS
Total investments		8,012
Level 1 [Member]
ASSETS
Total assets measured at fair value	23,675	7,176
Level 1 [Member] \| Cash and cash equivalents [Member] \| Cash and money market funds [Member]
ASSETS
Total cash and cash equivalents	$ 23,675	7,176
Level 2 [Member]
ASSETS
Total assets measured at fair value		10,016
Level 2 [Member] \| Cash and cash equivalents [Member] \| U.S. government and agency securities [Member]
ASSETS
Total cash and cash equivalents		2,004
Level 2 [Member] \| Investments [Member]
ASSETS
Total investments		$ 8,012

Goodwill	12 Months Ended
Goodwill	Dec. 31, 2021
Goodwill [Abstract]
Goodwill	5. Goodwill In 2014, the Company acquired three companies (the acquisitions) for aggregate consideration of $5.5 million. In accordance with ASC Topic 805, Business Combinations, the Company recorded goodwill of $2.8 million in connection with the acquisitions, which represents the excess of consideration paid over the fair value of net tangible and intangible assets acquired. The Company reviews goodwill for impairment annually or whenever changes in circumstances indicate that the carrying amount of goodwill may not be recoverable. Based on the Company’s annual review as of December 31, 2021, the Company determined that its goodwill was not impaired.

Related Party Transactions (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands				1 Months Ended		12 Months Ended
	Jun. 30, 2021	Mar. 11, 2021	Feb. 04, 2021	Jul. 31, 2021	Jun. 30, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2014
Related Party Transaction [Line Items]
Common stock, shares issued						29,716,000	25,550,000
Common stock, par value						$ 0.001	$ 0.001
Proceeds from issuance of common stock						$ 56,697	$ 29,434
Coverage period						1 year
Private Placement [Member]
Related Party Transaction [Line Items]
Common stock, par value									$ 0.001
Chairman, Robert W. Duggan [Member]
Related Party Transaction [Line Items]
Proceeds from related party loan		$ 41,000
Chairman, Robert W. Duggan [Member] \| Private Placement [Member]
Related Party Transaction [Line Items]
Common stock, shares issued	3,048,780
Common stock, par value	$ 0.001
Price per share	$ 16.40
Aggregate issuance costs	$ 41,000
Net proceeds	50,000
Proceeds from issuance of common stock	$ 8,400			$ 8,400
MDB Capital Group, LLC [Member] \| Initial Public Offering [Member]
Related Party Transaction [Line Items]
Warrants/rights outstanding						0
Robert W. Duggan [Member]
Related Party Transaction [Line Items]
Due to related parties						$ 2,500
Robert W. Duggan [Member] \| Private Placement [Member]
Related Party Transaction [Line Items]
Price per share	$ 16.40
Wilson Sonsini Goodrich And Rosati (WSGR) [Member]
Related Party Transaction [Line Items]
Related party expenses						600	800	$ 500
Legal Expenses [Member] \| Wilson Sonsini Goodrich And Rosati (WSGR) [Member] \| Rights Offering [Member]
Related Party Transaction [Line Items]
Related party expenses							$ 400
Rights Offering [Member]
Related Party Transaction [Line Items]
Legal expenses capitalized						$ 200
Common stock, par value					$ 0.001
Net proceeds			$ 4,500		$ 29,400
Warrants/rights outstanding					641,571	0

Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
Revenue (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Consolidated revenue	$ 1,418
Redemption Of Non-Cash Credits [Member]
Disaggregation of Revenue [Line Items]
Consolidated revenue	1,100
Cash Purchases [Member]
Disaggregation of Revenue [Line Items]
Consolidated revenue	$ 300

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 30
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8906-108599

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9031-108599

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 41
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9038-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 32
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8933-108599

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130543-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e8736-108599

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=123359005&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=123351226&loc=SL49130545-203045

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

+ Details

Balance Sheet Components (Schedule Of Inventory) (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Balance Sheet Components [Abstract]
Raw materials	$ 2,010
Work in process	1,371
Finished goods	2,443
Total inventory	$ 5,824

Summary Of Significant Accounting Policies (Policy)	12 Months Ended
Summary Of Significant Accounting Policies (Policy)	Dec. 31, 2021
Summary Of Significant Accounting Policies [Abstract]
Going Concern	Going Concern As of December 31, 2021, the Company had an accumulated deficit of $236.2 million, cash outflows from operations of $54.1 million for the year then ended, cash and cash equivalents of $28.6 million, and a net loss of $63.7 million. The Company has recently begun to generate revenue from product sales, but anticipates net losses for the next several years or until it can generate substantial product revenue and achieve profitability. Based on the Company’s current operating plan, the Company has determined that, with its current financial resources, the Company would be able to operate into the second quarter of 2022. As the Company’s operating plan does not allow the Company to operate for a period of twelve months from the date the consolidated financial statements are issued without additional financing, based on the ASC 205-40, Presentation of Financial Statements – Going Concern, the Company is required to disclose that substantial doubt regarding the Company’s ability to continue as a going concern exists. This evaluation initially cannot take into consideration the potential mitigating effects of plans that have not been fully implemented as of the date the financial statements are issued. To continue to fund the operations of the Company beyond this time period, management has developed plans, which primarily consist of raising additional capital through some combination of public or private equity offerings, debt financings, the Company’s at-the-market equity offering program, and/or potential new collaborations. There is no assurance, however, that any additional financing or any revenue-generating collaboration will be available when needed or that management of the Company will be able to obtain financing or enter into a collaboration on terms acceptable to the Company. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty.
Basis Of Presentation	Basis of Presentation Certain prior period balances have been reclassified to conform to the current period presentation in the consolidated financial statements and the accompanying notes. Sales and marketing expenses are reclassified out of general and administrative expenses, both of which are presented as separate line items. Amortization of intangible assets are reclassified to general and administrative expenses.
Principles Of Consolidation	Principles of Consolidation The accompanying consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and pursuant to the rules and regulations of the United States Securities Exchange Commission (the “SEC”). The consolidated financial statements include the financial statements of the Company and its wholly-owned subsidiaries and intercompany balances and transactions have been eliminated in consolidation.
Use Of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates that affect the amounts reported in the financial statements and accompanying notes to the financial statements. Estimates include, but are not limited to, the valuation and recognition of share-based compensation, inventory valuation, warranty obligations, income taxes, and the useful lives assigned to long-lived assets. The Company evaluates its estimates and assumptions based on historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ materially from these estimates.
Concentration Of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents and investments. The Company places its cash equivalents and investments with high credit quality financial institutions and, by policy, limits the amounts invested with any one financial institution or issuer. Deposits held with banks may exceed the amount of insurance provided on such deposits. The Company has not experienced any losses since inception.
Fair Value Of Financial Instruments	Fair Value of Financial Instruments The Company believes the carrying amounts of its financial instruments, including cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses, approximate fair value due to the short-term nature of such instruments.
Cash, Cash Equivalents, And Investments	Cash, Cash Equivalents and Investments The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. The Company has designated all investments as available-for-sale and therefore, such investments are reported at fair value, with unrealized gains and losses recognized in accumulated other comprehensive income (loss) in stockholders’ equity. The cost of marketable securities is adjusted for the amortization of premiums and discounts to expected maturity. Premium and discount amortization is included in other income, net. Realized gains and losses, as well as interest income, on available-for-sale securities are also included in other income, net. The Company includes all of its available-for-sale securities in current assets. All of the Company’s investments are subject to annual impairment review. The Company recognizes an impairment loss when a decline in the fair value of its marketable investments below the cost basis is judged to be other-than-temporary. Factors considered in determining whether a loss is temporary include the length of time and extent to which the marketable investments fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, extent of the loss related to credit of the issuer, the expected cash flows from the security, the Company’s intent to sell the security and whether or not the Company will be required to sell the security before the recovery of its amortized cost. No impairment losses were incurred during the periods presented.
Property And Equipment	Property and Equipment Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or estimated useful life. Equipment is recorded at cost and depreciated using the straight-line method over their estimated useful lives, ranging from three to five years.
Valuation Of Inventory	Valuation of Inventory Inventory is stated at lower of cost or net realizable value. The Company establishes the inventory basis by determining the cost based on standard costs approximating the purchase costs on a first-in, first-out basis. Net realizable value is the estimated selling price in the ordinary course of the Company’s business, less reasonably predictable costs of completion, disposal, and transportation. The cost basis of the Company’s inventory will be reduced for any products that are considered excessive or obsolete based upon assumptions about future demand and market conditions. At December 31, 2021, there is no reduction to the balance of inventory for excessive and obsolete inventory.
Intangible Assets	Intangible Assets The Company’s intangible assets consist of acquired patents and licenses, which are amortized over their estimated useful lives of twelve years.
Long-Lived Assets	Long-Lived Assets The Company reviews long-lived assets, consisting of property and equipment and intangible assets, for impairment during each fiscal year or when events or changes in circumstances indicate the carrying value of these assets may exceed their current fair values. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset. No impairment losses were incurred during the periods presented.
Goodwill	Goodwill The Company records goodwill when the consideration paid in a business acquisition exceeds the fair value of the net tangible assets and the identified intangible assets acquired. The Company reviews goodwill for impairment at the reporting unit level at least annually or whenever changes in circumstances indicate that the carrying value of the goodwill may not be recoverable. To date, there has been no impairment of goodwill.
Revenue From Contracts with Customers	Revenue from Contracts with Customers The Company recognizes revenue at a point in time when it satisfies performance obligations by transferring control of promised goods to its customers. The amount of revenue recognized is equal to the consideration which the Company is entitled to in exchange for the promised goods, excluding any amounts assessed by government authorities for taxes which might be collected from a customer. Sales contracts often involve the sale and delivery of multiple products, each of which typically represent a separate performance obligation in the contract. While the Company sells these products on a stand-alone basis at their respective SSP, initial customer contracts will likely involve the bundling of products which will be delivered concurrently to the customer. In such instances, the full consideration of the contract will be recognized upon shipment of the products. The Company generally requires receipt of full payment prior to shipment, however, from time to time, payment terms may be extended to customers upon which the Company will perform a necessary credit evaluation to ensure future collectability of the outstanding balance. The Company does not believe any portion of the outstanding accounts receivable balance to be uncollectible, and has therefore not recorded an allowance against the accounts receivable balance. Refer to Note 9 for further details.
Product Warranty	Product Warranty The Company provides a standard warranty on eligible products which provides the customer assurances that the products comply with the agreed-upon specifications. The standard warranty does not provide any services in addition to those assurances. The Company accrues a warranty reserve for products sold based upon the best estimate of the nature, frequency, and costs of future claims. These estimates are inherently uncertain given the short history of sales, and changes to the historical or projected warranty experience may cause material changes to the warranty reserve in the future. The warranty reserve is included within Accrued expenses on the consolidated balance sheets. Warranty expense is recorded as a component of Cost of Revenues in the consolidated statements of operations and comprehensive loss. Warranty accrual activity consisted of the following (in thousands): Year Ended December 31, 2021 2020Beginning balance $ — $ — Add: Accruals for warranties issued during the period 80 — Less: Settlements made during the period — —Ending balance $ 80 $ —
Stock-Based Compensation	Stock-Based Compensation The Company recognizes the cost of stock-based compensation in the financial statements based upon fair value. The fair value of stock options is determined as of the grant date using the Black-Scholes option pricing model. The fair value of Restricted Stock Units (“RSU”) awards is determined based on the number of units granted and the closing price of the Company’s common stock on the grant date. The fair value of each purchase under the employee stock purchase plan (“ESPP”) is estimated at the beginning of the offering period using the Black-Scholes option pricing model. The Company’s determination of the fair value of equity-settled awards is impacted by the price of the Company’s common stock as well as changes in assumptions regarding a number of complex and subjective variables. These variables include, but are not limited to, the expected term that awards will remain outstanding, expected common stock price volatility over the term of the awards, risk-free interest rates and expected dividends. The fair value of an award is recognized over the period during which service is required to be performed in exchange for the award, the requisite service period (usually the vesting period) on a straight-line basis. The Company accounts for all equity instruments awarded to non-employees at the fair value of the award issued on the day of the grant. The fair value of these equity instruments are expensed over the requisite service period. Certain stock options awarded to the Company’s executives and other key employees contain performance conditions related to certain financial measures and achievements of strategic/operational milestones (“performance options”). These performance options can contain both service and performance-based vesting conditions. The fair value of these performance options is recognized using the graded vesting method over the requisite service period beginning in the period in which the awards are deemed probable to vest, to the extent such awards are probable to vest. Estimates of the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, are affected by assumptions regarding a number of complex variables. Changes in the assumptions can materially affect the fair value of the award and the stock-based compensation expense recognized. These inputs are subjective and generally require significant analysis and judgment to develop. The Company determines the volatility factor based on the weighted average of its own historical volatility and those of comparable public companies in similar industries. The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award. For all stock options granted to date, the Company used the simplified method to calculate the expected term, which is the average of the contractual term and vesting period. See Note 6 for a detailed discussion of the Company’s stock plans and stock-based compensation expense.
Research And Development Costs	Research and Development Costs Research and development costs consist primarily of compensation costs, fees paid to consultants and outside service providers and organizations (including university research institutes), costs associated with clinical trials, development prototypes and other expenses relating to the acquisition, design, development and testing of the Company’s product candidates, and certain facilities related costs. Research and development costs incurred by the Company are expensed as incurred, unless the achievement of milestones, the completion of contracted work, or other information indicates that a different expensing schedule is more appropriate.
Patent Costs	Patent Costs The Company is the owner of numerous domestic and foreign patents. Due to the significant uncertainty associated with the successful development of one or more commercially viable products based on the Company’s research efforts and any related patent applications, patent costs not related to acquired patents, including patent-related legal fees, filing fees and other costs, including internally generated costs, are expensed as incurred. During the years ended December 31, 2021, 2020 and 2019, patent costs totaled $0.6 million, $0.5 million and $0.6 million, respectively. Patent costs are included in general and administrative costs in the consolidated statements of operations and comprehensive loss.
Income Taxes	Income Taxes The Company accounts for income taxes under an asset and liability approach for financial accounting and reporting for income taxes. Accordingly, the Company recognizes deferred tax assets and liabilities for the expected impact of differences between the financial statements and the tax basis of assets and liabilities. The Company records a valuation allowance to reduce its deferred tax assets to the amount that is more-likely-than-not to be realized. In the event the Company determines that it would be able to realize its deferred tax assets in the future in excess of its recorded amount, an adjustment to the deferred tax assets would be credited to operations in the period such determination was made. Likewise, should the Company determine that it would not be able to realize all or part of its deferred tax assets in the future, an adjustment to the deferred tax assets would be charged to operations in the period such determination was made. The Company is subject to U.S. federal income taxes and state income taxes in various states. As the Company’s net operating losses have yet to be utilized, previous tax years remain open to examination by federal authorities and other jurisdictions in which the Company currently operates or has operated in the past. The Company is not currently under examination by any tax authority. The Company accounts for uncertainties in income tax law under a comprehensive model for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns as prescribed by U.S. GAAP. The tax effects of a position are recognized only if it is more-likely-than-not to be sustained by the taxing authority as of the reporting date. If the tax position is not considered more-likely-than-not to be sustained, then no benefits of the position are recognized. At December 31, 2021 and 2020, the Company had not recorded any liability for uncertain tax positions. The Company includes interest and penalties related to uncertain tax positions as a component of income tax expense.
Comprehensive Loss	Comprehensive Loss Comprehensive loss consists of net loss and unrealized gains or losses on available-for-sale investments. The Company displays comprehensive loss and its components as part of the consolidated statements of operations and comprehensive loss.
Net Loss Per Share	Net Loss per Share The Company calculates basic net loss per share by dividing net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential dilutive common stock equivalents outstanding during the period. For purposes of this calculation, options to purchase common stock and common stock warrants are considered common stock equivalents. Potential common shares that have an anti-dilutive effect (i.e., those that increase income per share or decrease loss per share) are excluded from the calculation of diluted net loss per share. The following outstanding stock options, warrants, and RSUs to purchase common stock were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an anti-dilutive effect: Year Ended December 31, 2021 2020 2019Common stock warrants — 612,310 167,847Common stock options 5,996,813 5,039,194 3,749,186Restricted stock units — 111,305 222,606Total 5,996,813 5,762,809 4,139,639
Segment And Geographical Information	Segment and Geographical Information The Company operates in one segment and reports segment information in accordance with ASC 280, Segment Reporting. Management uses one measurement of profitability and does not segregate its business for internal reporting, however in making certain operating decisions and assessing performance, management will additionally review the disaggregated revenue results by product and geography. As of December 31, 2021 and 2020, 100% of long-lived assets were in the United States. Revenue is attributed to a geographic region based on the location of the end customer. See Note 10 for details of revenue by product and geography.
Recent Accounting Pronouncement	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers, requiring an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. This updated standard became effective for the Company in the first quarter of fiscal year 2018. The Company began to recognize revenue in 2021 using this updated standard. See Note 9 for additional details of the revenue recognition approach. In November 2018, the FASB issued ASU No. 2018-18 Collaborative Arrangements – Clarifying the Interaction between Topic 808 (Collaborative Arrangements) and Topic 606 (Revenue from Contracts with Customers), which clarifies the interaction between ASC 808, Collaborative Arrangements and ASC 606, Revenue from Contracts with Customers (“ASC 606”). The ASU clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC 606 when the counterparty is a customer. In addition, the ASU precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue if the counterparty is not a customer for that transaction. The Company adopted the standard on January 1, 2020, however, did not record revenue until August 2021 and does not currently have any collaborative arrangements in place. The adoption of the new standard had no impact on the Company’s consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions related to the general principles in ASC 740 and makes amendments to other areas with the intention of simplifying various aspects related to accounting for income taxes. The new standard is effective for fiscal years beginning after December 15, 2020, including interim periods therein; with early adoption permitted. The Company adopted the Topic 740 effective January 1, 2021. The adoption did not have a material impact on the Company’s financial statements.

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2021
Related Party Transactions [Abstract]
Related Party Transactions	12. Related Party Transactions Kenneth A. Clark, a director of the Company from November 2017 to October 2021, is a member of the law firm of Wilson Sonsini Goodrich and Rosati (“WSGR”), which also served as the outside corporate counsel to the Company until November 18, 2021. During the years ended December 31, 2021, 2020 and 2019, the Company incurred expenses reported in general and administrative expenses in the consolidated statement of operations for legal services rendered by WSGR totaling approximately $0.6 million, $0.8 million and $0.5 million, respectively. During the year ended December 31, 2021, the Company capitalized approximately $0.2 million for legal expenses incurred in connection with the Sales Agreement. During the year ended December 31, 2020, the Company capitalized approximately $0.4 million for legal expenses incurred in connection with the 2020 rights offering. In October 2021, Mr. Clark resigned from the Company’s Board of Directors, and in November 2021, the Board terminated the engagement of WSGR and appointed Baker & Hostetler LLP as the Company’s outside corporate counsel. In May 2020, the Company determined not to renew its director and officer liability insurance policies due to disproportionately high premiums quoted by insurance companies. Instead, Robert W. Duggan, majority stockholder and Board Chairman, and the Company entered into a letter agreement, dated May 12, 2020 (the “Letter Agreement”), pursuant to which Mr. Duggan agreed with the Company to personally provide indemnity coverage on substantially the same terms as the Company’s prior coverage program for a one-year period, and has deposited security for such obligations. On May 13, 2021, in accordance with terms of the Letter Agreement, the Company paid Mr. Duggan the amount of $2.5 million. The Company did not enter into a new Letter Agreement with Mr. Duggan for the subsequent policy period, and in May 2021 secured its director and officer liability insurance through third-party insurance carriers. In June 2020, the Company completed the Rights Offering (Note 6). Mr. Duggan participated in the Rights Offering and purchased an aggregate of 2,561,873 Units.On March 11, 2021, the Company and Mr. Duggan entered into a Loan Agreement in connection with Mr. Duggan lending the principal sum of $41.0 million to the Company (Note 13).On June 30, 2021, the Company and Mr. Duggan entered into a Securities Purchase Agreement (Note 6), pursuant to which the Company issued and sold to Mr. Duggan 3,048,780 shares of the Company’s common stock, par value $0.001 per share, in a Private Placement, at a price per share of $16.40, for an aggregate investment in the amount of $50.0 million. The shares were paid for through (i) the conversion of the $41 million aggregate principal amount under the Loan Agreement, together with all accrued and unpaid interest outstanding, owed to Mr. Duggan under the Loan Agreement by and between the Company and Mr. Duggan (Note 13), and (ii) additional cash in the amount of approximately $8.4 million. Upon the closing of this Private Placement and satisfaction of the outstanding debt, the Loan Agreement terminated, without any early termination fees or penalties being owed by the Company, and no additional amounts were owed to Mr. Duggan under the Loan Agreement.

Research Grants And Agreements	12 Months Ended
Research Grants And Agreements	Dec. 31, 2021
Research Grants And Agreements [Abstract]
Research Grants And Agreements	7. Research Grants and Agreements Sponsored Research Agreement The Company entered into a SRA with ODURF during 2014 pursuant to which the Company sponsors research activities performed by ODURF’s Frank Reidy Center. ODURF is compensated by the Company for its conduct of each study in accordance with the budget and payment terms set forth in the applicable task order. In August 2018, we agreed to sponsor a task order for research in the amount of $0.8 million and in September 2019, we agreed to sponsor an additional task order for research in the amount of $0.8 million each to be performed during their respective subsequent 12-month periods. In March 2021, we agreed to sponsor a task order for research in the amount of $0.3 million and in May 2021 we sponsored an additional task order for $0.3 million each to be performed during their respective subsequent 12-month periods. These sponsored researches are funded through monthly payments made upon ODURF certifying, to our reasonable satisfaction, that ODURF has met its obligations pursuant to the specified task order and statement of work. The principal investigator may transfer funds within the budget as needed with our approval so long as the obligations of ODURF under the task order and statement of work remain unchanged and unimpaired. During the years ended December 31, 2021, 2020, and 2019, we incurred costs relating to the SRA equal to $0.3 million, $0.6 million and $0.9 million, respectively. As of December 31, 2021, there is a $0.3 million balance payable under this research agreement.

Stockholders' Equity And Stock-Based Compensation	12 Months Ended
Stockholders' Equity And Stock-Based Compensation	Dec. 31, 2021
Stockholders' Equity And Stock-Based Compensation [Abstract]
Stockholders' Equity And Stock-Based Compensation	6. Stockholders’ Equity and Stock-Based Compensation Preferred Stock The Company has authorized a total of 50,000,000 shares of preferred stock, par value $0.001 per share, none of which were outstanding at December 31, 2021 and 2020. The Company’s Board of Directors (the “Board”) has the authority to issue preferred stock and to determine the rights, preferences, privileges, and restrictions, including voting rights, without any further vote or action by the Company’s stockholders. Common Stock The Company has authorized a total of 500,000,000 shares of common stock, par value $0.001 per share.Private Placement Securities Purchase Agreement On June 30, 2021, the Company entered into a Securities Purchase Agreement with Robert W. Duggan, the Company’s largest stockholder and Board Chairman, pursuant to which the Company issued and sold to Mr. Duggan 3,048,780 shares of the Company’s common stock, par value $0.001 per share, in a private placement (the “Private Placement”), at a price per share of $16.40, which was the market closing price on the date of the transaction. These shares were paid for through (i) the conversion of $41.0 million aggregate principal amount, together with all accrued and unpaid interest outstanding, owed to Mr. Duggan under the Loan Agreement by and between the Company and Mr. Duggan (Note 13), and (ii) additional cash in the amount of approximately $8.4 million. Upon the closing of this Private Placement and satisfaction of the outstanding debt, the Loan Agreement terminated, without any early termination fees or penalties being owed by the Company, and no additional amounts were owed to Mr. Duggan under the Loan Agreement. The cash proceeds of approximately $8.4 million were received by the Company in July 2021. At-the-Market Equity Offering On February 4, 2021, the Company entered into a sales agreement (the “Sales Agreement”) with Stifel, Nicolaus & Company, Inc. (“Stifel”) as sales agent, pursuant to which the Company may offer and sell, from time to time, through Stifel, up to $60.0 million in shares of common stock, by any method permitted by law deemed to be an “at-the-market” offering as defined in Rule 415 promulgated under the Securities Act of 1933, as amended. The Company has no obligation to make any sales of its common stock pursuant to such Sales Agreement. During the year ended December 31, 2021, the Company issued and sold 288,490 shares of common stock under the Sales Agreement. The shares were sold at a weighted average price of $27.73 per share for aggregate net proceeds of approximately $7.4 million, after deducting sales commissions and offering costs payable by the Company. Rights Offering During June 2020, the Company completed a rights offering to purchase up to $30.0 million of units, each unit consisting of one share of the Company’s common stock, par value $0.001 per share, and 0.15 warrants to purchase shares of common stock (the “Units”) at a price of $7.01 per Unit (the “Rights Offering”). The common stock and warrants comprising the Units separated upon the closing of the Rights Offering and were issued separately. A total of 4,279,600 shares of common stock and 641,571 warrants (the “Rights Offering Warrants”) were issued and sold in the Rights Offering for net proceeds of approximately $29.4 million. Each warrant was exercisable for one share of the Company’s common stock at an exercise price equal to $7.01, the subscription price for the Units. The Rights Offering Warrants were exercisable immediately and expired on the fifth anniversary of the completion of the Rights Offering, or June 16, 2025, subject to certain redemption rights by the Company. The Rights Offering Warrants were subject to redemption by the Company, on or after December 16, 2020, six months after the issuance date, for $0.01 per warrant, with not less than 30 days written notice, if the volume weighted average price of our common stock equaled or exceeded 200% of the exercise price for the Rights Offering Warrants for 10 consecutive trading days. Common Stock Warrants In connection with a private placement offering of the Company’s shares of common stock, par value $0.001 per share in 2014, the Company issued warrants as compensation to the placement agent to purchase a total of 299,625 shares of its common stock at a price of $2.67 per share (the “Private Placement Warrants”). The Private Placement Warrants were exercisable for a period of seven years. In March 2021, warrants to purchase 45,638 shares of common stock were net exercised, resulting in the issuance of 40,563 shares of common stock. As of December 31, 2021, there were no Private Placement Warrants outstanding. In connection with the closing of the Company’s initial public offering in 2016, the Company issued warrants as compensation to its underwriters, as representatives of the underwriters of its initial public offering to purchase a total of 574,985 shares of its common stock at a price of $5.00 per share (the “IPO Warrants”). The IPO Warrants were exercisable for a period of five years. In March 2021, warrants to purchase 85,385 shares of common stock were net exercised, resulting in the issuance of 68,958 shares of common stock. As of December 31, 2021, there were no IPO Warrants outstanding. In connection with the Rights Offering, the Company issued warrants (“Rights Offering Warrants”) to purchase a total of 641,571 shares of its common stock at an exercise price of $7.01. On December 31, 2020 the Company met the requirements for redemption of these warrants and delivered a notice of redemption to redeem all of the outstanding Rights Offering Warrants that remained unexercised at February 5, 2021, for the redemption price of $0.01 per warrant. Pursuant to the redemption, the Company redeemed 5,139 warrants. Prior to the February 5, 2021 redemption date, 636,432 warrants were exercised, generating approximately $4.5 million of total gross proceeds to the Company. As of December 31, 2021, there were no Rights Offering Warrants outstanding. A summary of total warrants activity for the year ended December 31, 2021 is presented below: Weighted Average Weighted Remaining Number of Average Contractual Shares Exercise Price Life (in Years)Warrants outstanding at December 31, 2020 612,310 $ 6.40 0.26 Issued — — Exercised (585,069) 6.47 Expired/Redeemed (27,241) 3.56 Warrants outstanding and exercisable at December 31, 2021 — $ — — Equity Plans 2017 Equity Incentive Plan and 2017 Inducement Equity Incentive PlanThe Board previously adopted, and the Company’s stockholders approved, the Company’s 2017 Equity Incentive Plan (the “2017 Plan”).The 2017 Plan has a 10-year term, and provides for the grant of stock options, stock appreciation rights, restricted stock, RSUs, performance units, and performance shares to employees, directors and consultants of the Company and any parent or subsidiary of the Company, as the Compensation Committee of the Board may determine. Subject to an annual evergreen increase and adjustment in the case of certain capitalization events, the Company initially reserved 1,500,000 shares of the Company’s common stock for issuance pursuant to awards under the 2017 Plan. In addition, shares remaining available under the Company’s 2015 Equity Incentive Plan, as amended (the “2015 Plan”), and shares reserved but not issued pursuant to outstanding equity awards that expire or terminate without being exercised or that are forfeited or repurchased by the Company will be added to the shares of common stock available for issuance under the 2017 Plan. The 2017 Plan is administered by the Board’s Compensation Committee. Effective January 1, 2021 and 2020, the number of shares of common stock available under the 2017 Plan increased by 1,022,002 and 833,018 shares, respectively, pursuant to the evergreen provision of the 2017 Plan. Under the evergreen provision of the 2017 Plan, the share increase is determined based on the least of (i) 1,200,000 shares, (ii) 4% of the Company’s common stock outstanding at December 31 of the immediately preceding year, or (iii) such number of shares as determined by the Board. As of December 31, 2021, 443,196 shares of common stock remained available for issuance under the 2017 Plan.During November 2017, the Board of the Company adopted the 2017 Inducement Equity Incentive Plan (the “Inducement Plan”) and reserved 1,000,000 shares of the Company’s common stock for issuance pursuant to equity awards granted under the Inducement Plan. The Inducement Plan was adopted without stockholder approval.The Inducement Plan has a 10-year term and provides for the grant of equity-based awards, including non-statutory stock options, RSUs, restricted stock, stock appreciation rights, performance shares and performance units, and its terms are substantially similar to the 2017 Plan, including with respect to treatment of equity awards in the event of a “merger” or “change in control” as defined under the Inducement Plan. Options issued under the Inducement Plan may have a term up to ten years and have variable vesting provisions. New hire grants generally vest 25% per year starting upon the first anniversary of the grant. Equity-based awards issued under the Inducement Plan are only issuable to individuals not previously engaged as employees or non-employee directors of the Company prior to the Inducement Plan’s adoption date. In May 2021, the Board approved an amendment to the Inducement Plan to reserve an additional 1,000,000 shares of the Company’s common stock for issuance pursuant to the Inducement Plan. As of December 31, 2021, 1,044,513 shares of common stock were available for issuance under the Inducement Plan. A summary of stock option activity under the 2015 Plan, 2017 Plan and Inducement Plan for the year ended December 31, 2021 is presented below: Weighted Weighted Average Average Remaining Number of Exercise Contractual Shares Price Life (in Years)Balances - December 31, 2020 5,039,194 $ 14.26 7.83 Options granted 1,239,588 22.10 Options exercised (53,731) 11.47 Options canceled (162,975) 16.94 Options expired (65,263) 19.92 Balances - December 31, 2021 5,996,813 $ 15.77 7.33Stock options exercisable at December 31, 2021 3,312,074 $ 15.96 6.23 Time-based Options The Company awards time-based options which vest and become exercisable, subject to the individual’s continued employment or service through the applicable vesting date. Time-based options can have various vesting schedules, most commonly new hire grants which generally vest 25% per year starting upon the first anniversary of the grant. A summary of the time-based stock option activity under the 2015 Plan, 2017 Plan and Inducement Plan for the year ended December 31, 2021 is presented below: Stock Options Outstanding Number ‎of shares Weighted‎average‎exercise price Weighted‎average‎remaining life‎(in years)Balances — December 31, 2020 4,055,352 $15.04 6.37 Options granted 1,023,333 22.04 Options exercised (53,731) 11.47 Options canceled (162,975) 16.94 Options expired (65,263) 19.92 Balances — December 31, 2021 4,796,716 $16.44 7.05 Exercisable — December 31, 2021 3,018,902 $16.38 6.05 The intrinsic value of time-based options exercised during the year ended December 31, 2021, 2020 and 2019 was $0.8 million, $1.6 million, and $1.0 million, respectively. The fair value of the time-based options granted to employees and directors during the years ended December 31, 2021, 2020 and 2019 was $15.1 million, $6.7 million, and $8.4 million, respectively. Performance Options Certain stock options awarded to the Company’s executives and other key employees contain performance conditions related to certain financial measures and achievements of strategic/operational milestones. The options will vest and become exercisable once the specific performance condition is fulfilled. A summary of the performance option activity under the 2017 Plan and Inducement Plan for the year ended December 31, 2021 is presented below: Stock Options Outstanding Number ‎of shares Weighted‎average‎exercise price Weighted‎average‎remaining life‎(in years)Balances — December 31, 2020 983,842 $11.06 8.25 Options granted 216,255 22.41 Options exercised — — Options canceled — — Options expired — — Balances — December 31, 2021 1,200,097 $13.11 8.44 Exercisable — December 31, 2021 293,172 $11.64 8.08 The fair value of the performance options granted to employees during the years ended December 31, 2021, 2020 and 2019 was $2.5 million, $5.5 million, and $0.4 million, respectively. The fair value of employee stock options was estimated using the Black-Scholes option-pricing model utilizing the following assumptions: Year Ended December 31, 2021 2020 2019Expected term in years 5.3 - 6.1 5.3 - 6.1 0.4 - 6.1Expected volatility 78% 70% 70%Risk-free interest rate 0.9 - 1.4% 0.3 - 0.5% 1.4 - 2.6%Dividend yield — — — 2017 Employee Stock Purchase Plan The Board previously adopted and the stockholders approved the Company’s 2017 Employee Stock Purchase Plan (the “2017 ESPP”). The 2017 ESPP is a broad-based plan that provides employees of the Company and its designated affiliates with the opportunity to become stockholders through periodic payroll deductions that are applied towards the purchase of Company common shares at a discount from the then-current market price. Subject to adjustment in the case of certain capitalization events, a total of 250,000 common shares of the Company were available for purchase at adoption of the 2017 ESPP. Pursuant to the 2017 ESPP, the annual share increase pursuant to the evergreen provision is determined based on the least of (i) 450,000 shares, (ii) 1.5% of the Company’s common stock outstanding at December 31 of the immediately preceding year, or (iii) such number of shares as determined by the Board. In 2020 the Board determined not to increase the number of shares of common stock available pursuant to the evergreen provision. Effective January 1, 2021, pursuant to the evergreen provision of the 2017 ESPP, the number of shares of common stock available under the 2017 ESPP was increased by 383,250 shares. During the years ended December 31, 2021 and 2020, the Company issued 91,378 and 82,971 shares of common stock under the 2017 ESPP, respectively. As of December 31, 2021, 649,096 shares of common stock remained available for issuance under the 2017 ESPP. The fair value of ESPP was estimated using the Black-Scholes option-pricing model utilizing the following assumptions: Year Ended December 31, 2021 2020 2019Expected term in years 0.5 - 1.0 0.5 - 1.0 0.5 - 1.0Expected volatility 78% 70% 70%Risk-free interest rate 0.06% - 0.1% 0.1% - 1.0% 1.7% - 2.6%Dividend yield — — — Restricted Stock Units The fair value of RSU awards is determined based on the number of units granted and the closing price of the Company’s common stock as of the grant date. The estimated fair value of RSUs is recognized on a straight-line basis over the requisite service period. During the year ended December 31, 2017, the Company granted 160,974 RSUs to the Chief Executive Officer, all of which vested in June 2018. These shares were partially released in 2019, resulting in a net issuance of shares. Additional paid in capital was reduced for tax payments related to shares withheld in connection with the release. The remaining shares under this grant were released in 2021, and at December 31, 2021 no shares were outstanding under this grant. There was no stock-based compensation expense related to these RSUs recorded in the years ended December 31, 2021, 2022 and 2019. As of December 31, 2021, there was no unrecognized compensation expense related to these RSUs. During the year ended December 31, 2017, the Company granted 68,800 RSUs to certain employees, of which 50% vested on June 1, 2019 while the remaining 50% vested on June 1, 2021. The stock-based compensation expense recorded in the years ended December 31, 2021, 2020, and 2019 related to these RSUs was approximately $0.1 million, $0.3 million, and $0.4 million, respectively. As of December 31, 2021, there was no unrecognized compensation expense related to these RSUs. Stock-based Compensation Total stock-based compensation expense recorded in the consolidated statements of operations and comprehensive loss was as follows (in thousands): Year Ended December 31, 2021 2020 2019Cost of revenues $ 129 $ — $ —Research and development 5,211 4,013 3,821Sales and marketing 2,749 1,187 883General and administrative 6,512 4,875 6,583Total stock-based compensation expense $ 14,601 $ 10,075 $ 11,287 As of December 31, 2021, not all of the performance conditions of the performance options are probable to be achieved. Compensation expense has only been recognized for those conditions that are assumed to be probable. In February 2021, the Compensation Committee approved of a modification to certain vesting conditions of outstanding Performance Options. The Company had not recognized any compensation expense in relation to these Performance Options as the performance condition was previously deemed to be improbable. However, upon modification those specific performance conditions were deemed probable and fully vested. As such, during the year ended December 31, 2021, the full expense in relation to the amended performance conditions was recognized resulting in $4.1 million of additional stock-compensation expense. In October 2021, the Board amended the outstanding option awards of Kenneth A. Clark upon his resignation from the Board. The requirement that Mr. Clark exercise his vested options within ninety days of his resignation was waived. Mr. Clark will have the ability to exercise his outstanding vested option awards at any time during their ten-year term from the date of each grant, subject to earlier termination as may occur under the 2017 Plan. This amendment resulted in $1.4 million of additional stock-compensation expense during the year ended December 31, 2021. Total stock-based compensation expense by type was as follows (in thousands): Year Ended December 31, 2021 2020 2019Time-based options $ 9,235 $ 8,739 $ 10,895Performance options 4,840 133 100RSU — 86 —ESPP 526 1,117 292Total stock-based compensation expense $ 14,601 $ 10,075 $ 11,287 At December 31, 2021, there was $15.8 million of unrecognized compensation cost related to unvested stock-based compensation arrangements, which is expected to be recognized over a weighted average period of 2.7 years.

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (63,660)	$ (49,851)	$ (46,971)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	480	430	494
Amortization of intangible assets	666	665	666
Stock-based compensation	14,601	10,075	11,287
Net premium amortization and discount on available-for-sale securities	13	5	(521)
Loss on disposal of fixed assets		119
Gain on U.S. Treasury securities		(8)
Changes in operating assets and liabilities:
Accounts receivable	(61)
Inventory	(5,824)
Prepaid expenses and other current assets	(1,374)	194	(226)
Other receivables	54
Right-of-use assets	653	509	68
Other long-term assets		129	(393)
Accounts payable	1,160	(266)	646
Accrued expenses	(937)	2,830	841
Deferred revenue	16
Lease liabilities	(542)	(196)	(76)
Accrued interest on note payable	658
Net cash used in operating activities	(54,097)	(35,365)	(34,185)
Cash flows from investing activities:
Purchases of property and equipment	(437)	(441)	(608)
Purchases of investments		(29,025)	(77,993)
Maturities of investments	8,000	35,000	68,500
Sales of investments		4,510
Net cash provided by (used in) investing activities	7,563	10,044	(10,101)
Cash flows from financing activities:
Proceeds from issuance of common stock under employee stock purchase plan	810	490	423
Proceeds from exercises of warrants	4,217	244
Proceeds from exercises of stock options	786	717	272
Proceeds from issuance of common stock	56,697	29,434
Proceeds from insurance loan agreement	1,939
Payments made on insurance loan agreement	(1,532)
Tax payments related to shares withheld for vested restricted stock units	(232)		(613)
Net cash provided by financing activities	62,685	30,885	82
Net increase (decrease) in cash and cash equivalents	16,151	5,564	(44,204)
Cash and cash equivalents at beginning of period	12,463	6,899	51,103
Cash and cash equivalents at end of period	28,614	12,463	6,899
Supplemental disclosure of noncash investing and financing activities:
Other receivable from exercise of warrants and stock options		1,053
Change in unrealized gains on available-for-sale securities	1	(5)	5
Equipment purchases included in accounts payable and accrued expenses	27	$ 20	$ 279
Accrued interest settled via issuance of common stock from private placement equity offering	$ 629

Supplementary Financial Information	12 Months Ended
Supplementary Financial Information	Dec. 31, 2021
Supplementary Financial Information [Abstract]
Supplementary Financial Information	15. Supplementary Financial Information There are no retrospective changes to the statements of comprehensive income for any of the quarters within the two most recent fiscal years that individually or in the aggregate are material.

Stockholders' Equity And Stock-Based Compensation (Summary Of Stock-Based Compensation Expense By Type) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Total stock-based compensation expense	$ 14,601	$ 10,075	$ 11,287
Time-Based Options [Member]
Total stock-based compensation expense	9,235	8,739	10,895
Performance Shares [Member]
Total stock-based compensation expense	4,840	133	100
Restricted Stock Units [Member]
Total stock-based compensation expense		86
ESPP [Member]
Total stock-based compensation expense	$ 526	$ 1,117	$ 292

Income Taxes (Reconciliation Of Unrecognized Tax Benefit Accounts) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Income Taxes [Abstract]
Unrecognized tax benefits, Beginning balance	$ 2,491	$ 1,470	$ 877
Increases related to current year tax positions	2,649	1,021	593
Unrecognized tax benefits, Ending balance	$ 5,140	$ 2,491	$ 1,470

Income Taxes (Components of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Current
State	$ 3	$ 3	$ 3
Total current	3	3	3
Total provision for income taxes	$ 3	$ 3	$ 3

Income Taxes	12 Months Ended
Income Taxes	Dec. 31, 2021
Income Taxes [Abstract]
Income Taxes	11. Income Taxes Income (loss) before income taxes (in thousands): Year Ended December 31, 2021 2020 2019Domestic $ (63,660) $ (49,851) $ (46,971)Foreign — — — $ (63,660) $ (49,851) $ (46,971) The components of the provision for income taxes are as follows (in thousands): December 31, 2021 2020 2019Current Federal $ — $ — $ —State 3 3 3Foreign — — —Total current 3 3 3 Deferred Federal — — —State — — —Foreign — — —Total deferred — — — Total provision for income taxes $ 3 $ 3 $ 3 The provision for income taxes differs from the amount estimated by applying the statutory federal income tax rate to income (loss) before taxes as follows: Year Ended December 31, 2021 2020 2019Federal tax at statutory rate 21.0% 21.0% 21.0%State tax (benefit) at statutory rate 8.4 8.4 (5.0) Research and development credits 1.9 2.1 2.0 Change in valuation allowance (26.8) (43.3) (18.0) Deferred adjustment — 8.5 — Change in tax rate — 4.2 — Uncertain Tax Position (2.3) — — Other (2.2) (0.8) — Provision for income taxes —% —% —% Note that for presentation purposes, the 2019 percentages have been changed to present the opposite value from what was previously disclosed to allow for proper comparability to current year percentages. Deferred income taxes reflect the impact of carryforwards and temporary differences between the amounts of assets and liabilities for financial reporting purposes and such amounts as measured by tax laws. The carryforwards and temporary differences, which give rise to a significant portion of the Company’s deferred tax asset (liability) as of December 31, 2021 and 2020, are as follows (in thousands): December 31, 2021 2020Deferred tax assets Accruals $ 1,034 $ 894Net operating loss carryforwards 49,246 36,531Tax credit carryforwards 6,611 5,431Stock-based compensation 12,188 9,391Lease liability under ASC 842 3,182 3,339Gross deferred tax assets 72,261 55,586Valuation allowance (69,006) (51,973)Total deferred tax assets 3,255 3,613 Deferred tax liabilities Intangibles (365) (486)ROU asset under ASC 842 (2,862) (3,096)Fixed assets (28) (31)Total deferred tax liabilities (3,255) (3,613) Net deferred tax assets/(liabilities) $ — $ — The Company’s unrecognized tax benefits as of December 31, 2021, 2020, and 2019 were $5.1 million, $2.5 million, and $1.5 million, respectively. If recognized, none of the unrecognized tax benefits would impact income tax expense to the extent that the Company continues to maintain a full valuation allowance against its deferred tax assets. A reconciliation of the beginning and ending amounts of unrecognized tax benefit is as follows (in thousands): December 31, 2021 2020 2019Unrecognized tax benefits at beginning of year $ 2,491 $ 1,470 $ 877Increases related to current year tax positions 2,649 1,021 593Unrecognized tax benefits at end of year $ 5,140 $ 2,491 $ 1,470 The Company’s policy is to recognize interest and penalties related to income taxes as components of interest expense and other expense, respectively. The Company did not accrue interest and penalties related to unrecognized tax benefits as of December 31, 2021 and does not anticipate any significant change within twelve months of this reporting date. The Company’s valuation allowance increased by $17.0 million in the year ended December 31, 2021 and increased by $21.6 million in the year ended December 31, 2020. As of December 31, 2021, the Company had federal and state net operating loss (“NOL”) carryforwards of $173.7 million and $163.4 million, respectively, which begin to expire in 2034. Of the total federal NOL carryforward of $173.7 million, approximately $148.0 million is carried forward indefinitely but is limited to 80% of the taxable income. As of December 31, 2021, the Company had approximately $5.3 million and $5.0 million of U.S. federal and California research and development (“R&D”) credits, respectively. The federal R&D credits begin to expire in 2035 and the California R&D credits have an indefinite carryforward period. The Company is subject to taxation in the United States for Federal and for State, within various states in which the Company operates. All jurisdictions and tax years currently remain open for IRS and state taxing authorities’ examination. As of December 31, 2021, the Company was not under examination by the Internal Revenue Service or any state tax jurisdiction. Internal Revenue Code Section 382 ownership change generally occurs if one or more stockholders or groups of stockholders who own at least 5% of our stock increase their ownership by more than 50 percentage points over their lowest ownership percentage within a rolling three-year period. Similar rules may apply under state tax laws. The Company is not aware of any ownership changes in this financial period ending on December 31, 2021.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI http://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI http://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI http://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Segment Reporting (Details) $ in Thousands	12 Months Ended
Segment Reporting (Details) $ in Thousands	Dec. 31, 2021 USD ($) segment	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of reportable segments \| segment	1
Number of operating segments \| segment	1
Consolidated revenue	$ 1,418
Systems Products [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Consolidated revenue	1,189
Cycle Units Products [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Consolidated revenue	229
North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Consolidated revenue	1,182
Rest Of World [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Consolidated revenue	$ 236

- Definition

+ References

+ Details

Income Taxes (Components Of Deferred Tax Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Income Taxes [Abstract]
Accruals	$ 1,034	$ 894
Net operating loss carryforwards	49,246	36,531
Tax credit carryforwards	6,611	5,431
Stock-based compensation	12,188	9,391
Lease liability under ASC 842	3,182	3,339
Gross deferred tax assets	72,261	55,586
Valuation allowance	(69,006)	(51,973)
Total deferred tax assets	3,255	3,613
Intangibles	(365)	(486)
ROU asset under ASC 842	(2,862)	(3,096)
Fixed assets	(28)	(31)
Total deferred tax liability	(3,255)	(3,613)
Net deferred tax assets/(liabilities)

Investments And Fair Value Of Financial Instruments (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Investments And Fair Value Of Financial Instruments [Abstract]
Impairment on investments	$ 0	$ 0
Transfers between level 1, 2, or 3	$ 0	$ 0

Segment Reporting (Tables)	12 Months Ended
Segment Reporting (Tables)	Dec. 31, 2021
Segment Reporting [Abstract]
Schedule Of Revenue By Product And Geographic Location	Year Ended December 31, 2021 2020 2019Systems $ 1,189 $ — $ —Cycle units 229 — —Total consolidated revenue $ 1,418 $ — $ —Revenue by geography consisted of the following (in thousands): Year Ended December 31, 2021 2020 2019North America $ 1,182 $ — $ —Rest of World 236 — —Total consolidated revenue $ 1,418 $ — $ —

Balance Sheet Components (Schedule Of Intangible Assets, Net) (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Balance Sheet Components [Abstract]
Acquired patents and licenses	$ 7,985	$ 7,985
Less: Accumulated amortization	(4,769)	(4,103)
Intangible assets, net	$ 3,216	$ 3,882

Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	$ (236,200,000)	$ (172,540,000)
Cash used in operating activities	(54,097,000)	(35,365,000)	$ (34,185,000)
Cash, cash equivalents, and investments	28,600,000
Net loss	(63,660,000)	(49,851,000)	(46,971,000)
Inventory valuation reserve	$ 0
Intangible asset useful life	12 years
Long-lived asset impairment	$ 0	0	0
Goodwill impairment	0
Patent costs	600,000	500,000	$ 600,000
Liability for uncertain tax positions	$ 0	$ 0
Maximum [Member] \| Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life	5 years
Minimum [Member] \| Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Useful life	3 years

Balance Sheet Components (Narrative) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jul. 31, 2017
Balance Sheet Components [Abstract]
Improvement allowance, capitalized				$ 2,100
Depreciation expense	$ 480	$ 430	$ 494
Intangible asset useful life	12 years

Summary Of Significant Accounting Policies	12 Months Ended
Summary Of Significant Accounting Policies	Dec. 31, 2021
Summary Of Significant Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	2. Summary of Significant Accounting Policies Going Concern As of December 31, 2021, the Company had an accumulated deficit of $236.2 million, cash outflows from operations of $54.1 million for the year then ended, cash and cash equivalents of $28.6 million, and a net loss of $63.7 million. The Company has recently begun to generate revenue from product sales, but anticipates net losses for the next several years or until it can generate substantial product revenue and achieve profitability. Based on the Company’s current operating plan, the Company has determined that, with its current financial resources, the Company would be able to operate into the second quarter of 2022. As the Company’s operating plan does not allow the Company to operate for a period of twelve months from the date the consolidated financial statements are issued without additional financing, based on the ASC 205-40, Presentation of Financial Statements – Going Concern, the Company is required to disclose that substantial doubt regarding the Company’s ability to continue as a going concern exists. This evaluation initially cannot take into consideration the potential mitigating effects of plans that have not been fully implemented as of the date the financial statements are issued. To continue to fund the operations of the Company beyond this time period, management has developed plans, which primarily consist of raising additional capital through some combination of public or private equity offerings, debt financings, the Company’s at-the-market equity offering program, and/or potential new collaborations. There is no assurance, however, that any additional financing or any revenue-generating collaboration will be available when needed or that management of the Company will be able to obtain financing or enter into a collaboration on terms acceptable to the Company. The accompanying consolidated financial statements have been prepared on a going concern basis, which contemplates the realization of assets and satisfaction of liabilities in the ordinary course of business. The consolidated financial statements do not include any adjustments relating to the recoverability and classification of recorded asset amounts or the amounts and classification of liabilities that might result from the outcome of this uncertainty. Basis of Presentation Certain prior period balances have been reclassified to conform to the current period presentation in the consolidated financial statements and the accompanying notes. Sales and marketing expenses are reclassified out of general and administrative expenses, both of which are presented as separate line items. Amortization of intangible assets are reclassified to general and administrative expenses. Principles of Consolidation The accompanying consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and pursuant to the rules and regulations of the United States Securities Exchange Commission (the “SEC”). The consolidated financial statements include the financial statements of the Company and its wholly-owned subsidiaries and intercompany balances and transactions have been eliminated in consolidation. Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires the Company to make estimates that affect the amounts reported in the financial statements and accompanying notes to the financial statements. Estimates include, but are not limited to, the valuation and recognition of share-based compensation, inventory valuation, warranty obligations, income taxes, and the useful lives assigned to long-lived assets. The Company evaluates its estimates and assumptions based on historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ materially from these estimates. Concentration of Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist of cash and cash equivalents and investments. The Company places its cash equivalents and investments with high credit quality financial institutions and, by policy, limits the amounts invested with any one financial institution or issuer. Deposits held with banks may exceed the amount of insurance provided on such deposits. The Company has not experienced any losses since inception. Fair Value of Financial Instruments The Company believes the carrying amounts of its financial instruments, including cash equivalents, prepaid expenses and other current assets, accounts payable and accrued expenses, approximate fair value due to the short-term nature of such instruments. Cash, Cash Equivalents and Investments The Company considers all highly liquid investments purchased with an original maturity of three months or less to be cash equivalents. The Company has designated all investments as available-for-sale and therefore, such investments are reported at fair value, with unrealized gains and losses recognized in accumulated other comprehensive income (loss) in stockholders’ equity. The cost of marketable securities is adjusted for the amortization of premiums and discounts to expected maturity. Premium and discount amortization is included in other income, net. Realized gains and losses, as well as interest income, on available-for-sale securities are also included in other income, net. The Company includes all of its available-for-sale securities in current assets. All of the Company’s investments are subject to annual impairment review. The Company recognizes an impairment loss when a decline in the fair value of its marketable investments below the cost basis is judged to be other-than-temporary. Factors considered in determining whether a loss is temporary include the length of time and extent to which the marketable investments fair value has been less than the cost basis, the financial condition and near-term prospects of the investee, extent of the loss related to credit of the issuer, the expected cash flows from the security, the Company’s intent to sell the security and whether or not the Company will be required to sell the security before the recovery of its amortized cost. No impairment losses were incurred during the periods presented. Property and Equipment Leasehold improvements are amortized using the straight-line method over the shorter of the lease term or estimated useful life. Equipment is recorded at cost and depreciated using the straight-line method over their estimated useful lives, ranging from three to five years. Valuation of Inventory Inventory is stated at lower of cost or net realizable value. The Company establishes the inventory basis by determining the cost based on standard costs approximating the purchase costs on a first-in, first-out basis. Net realizable value is the estimated selling price in the ordinary course of the Company’s business, less reasonably predictable costs of completion, disposal, and transportation. The cost basis of the Company’s inventory will be reduced for any products that are considered excessive or obsolete based upon assumptions about future demand and market conditions. At December 31, 2021, there is no reduction to the balance of inventory for excessive and obsolete inventory. Intangible Assets The Company’s intangible assets consist of acquired patents and licenses, which are amortized over their estimated useful lives of twelve years. Long-Lived Assets The Company reviews long-lived assets, consisting of property and equipment and intangible assets, for impairment during each fiscal year or when events or changes in circumstances indicate the carrying value of these assets may exceed their current fair values. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of an asset to the estimated undiscounted future cash flows expected to be generated by the asset. No impairment losses were incurred during the periods presented. Goodwill The Company records goodwill when the consideration paid in a business acquisition exceeds the fair value of the net tangible assets and the identified intangible assets acquired. The Company reviews goodwill for impairment at the reporting unit level at least annually or whenever changes in circumstances indicate that the carrying value of the goodwill may not be recoverable. To date, there has been no impairment of goodwill. Revenue from Contracts with Customers The Company recognizes revenue at a point in time when it satisfies performance obligations by transferring control of promised goods to its customers. The amount of revenue recognized is equal to the consideration which the Company is entitled to in exchange for the promised goods, excluding any amounts assessed by government authorities for taxes which might be collected from a customer. Sales contracts often involve the sale and delivery of multiple products, each of which typically represent a separate performance obligation in the contract. While the Company sells these products on a stand-alone basis at their respective SSP, initial customer contracts will likely involve the bundling of products which will be delivered concurrently to the customer. In such instances, the full consideration of the contract will be recognized upon shipment of the products. The Company generally requires receipt of full payment prior to shipment, however, from time to time, payment terms may be extended to customers upon which the Company will perform a necessary credit evaluation to ensure future collectability of the outstanding balance. The Company does not believe any portion of the outstanding accounts receivable balance to be uncollectible, and has therefore not recorded an allowance against the accounts receivable balance. Refer to Note 9 for further details. Product Warranty The Company provides a standard warranty on eligible products which provides the customer assurances that the products comply with the agreed-upon specifications. The standard warranty does not provide any services in addition to those assurances. The Company accrues a warranty reserve for products sold based upon the best estimate of the nature, frequency, and costs of future claims. These estimates are inherently uncertain given the short history of sales, and changes to the historical or projected warranty experience may cause material changes to the warranty reserve in the future. The warranty reserve is included within Accrued expenses on the consolidated balance sheets. Warranty expense is recorded as a component of Cost of Revenues in the consolidated statements of operations and comprehensive loss. Warranty accrual activity consisted of the following (in thousands): Year Ended December 31, 2021 2020Beginning balance $ — $ — Add: Accruals for warranties issued during the period 80 — Less: Settlements made during the period — —Ending balance $ 80 $ — Stock-Based Compensation The Company recognizes the cost of stock-based compensation in the financial statements based upon fair value. The fair value of stock options is determined as of the grant date using the Black-Scholes option pricing model. The fair value of Restricted Stock Units (“RSU”) awards is determined based on the number of units granted and the closing price of the Company’s common stock on the grant date. The fair value of each purchase under the employee stock purchase plan (“ESPP”) is estimated at the beginning of the offering period using the Black-Scholes option pricing model. The Company’s determination of the fair value of equity-settled awards is impacted by the price of the Company’s common stock as well as changes in assumptions regarding a number of complex and subjective variables. These variables include, but are not limited to, the expected term that awards will remain outstanding, expected common stock price volatility over the term of the awards, risk-free interest rates and expected dividends. The fair value of an award is recognized over the period during which service is required to be performed in exchange for the award, the requisite service period (usually the vesting period) on a straight-line basis. The Company accounts for all equity instruments awarded to non-employees at the fair value of the award issued on the day of the grant. The fair value of these equity instruments are expensed over the requisite service period. Certain stock options awarded to the Company’s executives and other key employees contain performance conditions related to certain financial measures and achievements of strategic/operational milestones (“performance options”). These performance options can contain both service and performance-based vesting conditions. The fair value of these performance options is recognized using the graded vesting method over the requisite service period beginning in the period in which the awards are deemed probable to vest, to the extent such awards are probable to vest. Estimates of the fair value of equity-settled awards as of the grant date using valuation models, such as the Black-Scholes option pricing model, are affected by assumptions regarding a number of complex variables. Changes in the assumptions can materially affect the fair value of the award and the stock-based compensation expense recognized. These inputs are subjective and generally require significant analysis and judgment to develop. The Company determines the volatility factor based on the weighted average of its own historical volatility and those of comparable public companies in similar industries. The risk-free interest rate is based on the yield available on U.S. Treasury zero-coupon issues similar in duration to the expected term of the equity-settled award. For all stock options granted to date, the Company used the simplified method to calculate the expected term, which is the average of the contractual term and vesting period. See Note 6 for a detailed discussion of the Company’s stock plans and stock-based compensation expense. Research and Development Costs Research and development costs consist primarily of compensation costs, fees paid to consultants and outside service providers and organizations (including university research institutes), costs associated with clinical trials, development prototypes and other expenses relating to the acquisition, design, development and testing of the Company’s product candidates, and certain facilities related costs. Research and development costs incurred by the Company are expensed as incurred, unless the achievement of milestones, the completion of contracted work, or other information indicates that a different expensing schedule is more appropriate. Patent Costs The Company is the owner of numerous domestic and foreign patents. Due to the significant uncertainty associated with the successful development of one or more commercially viable products based on the Company’s research efforts and any related patent applications, patent costs not related to acquired patents, including patent-related legal fees, filing fees and other costs, including internally generated costs, are expensed as incurred. During the years ended December 31, 2021, 2020 and 2019, patent costs totaled $0.6 million, $0.5 million and $0.6 million, respectively. Patent costs are included in general and administrative costs in the consolidated statements of operations and comprehensive loss. Income Taxes The Company accounts for income taxes under an asset and liability approach for financial accounting and reporting for income taxes. Accordingly, the Company recognizes deferred tax assets and liabilities for the expected impact of differences between the financial statements and the tax basis of assets and liabilities. The Company records a valuation allowance to reduce its deferred tax assets to the amount that is more-likely-than-not to be realized. In the event the Company determines that it would be able to realize its deferred tax assets in the future in excess of its recorded amount, an adjustment to the deferred tax assets would be credited to operations in the period such determination was made. Likewise, should the Company determine that it would not be able to realize all or part of its deferred tax assets in the future, an adjustment to the deferred tax assets would be charged to operations in the period such determination was made. The Company is subject to U.S. federal income taxes and state income taxes in various states. As the Company’s net operating losses have yet to be utilized, previous tax years remain open to examination by federal authorities and other jurisdictions in which the Company currently operates or has operated in the past. The Company is not currently under examination by any tax authority. The Company accounts for uncertainties in income tax law under a comprehensive model for the financial statement recognition, measurement, presentation and disclosure of uncertain tax positions taken or expected to be taken in income tax returns as prescribed by U.S. GAAP. The tax effects of a position are recognized only if it is more-likely-than-not to be sustained by the taxing authority as of the reporting date. If the tax position is not considered more-likely-than-not to be sustained, then no benefits of the position are recognized. At December 31, 2021 and 2020, the Company had not recorded any liability for uncertain tax positions. The Company includes interest and penalties related to uncertain tax positions as a component of income tax expense. Comprehensive Loss Comprehensive loss consists of net loss and unrealized gains or losses on available-for-sale investments. The Company displays comprehensive loss and its components as part of the consolidated statements of operations and comprehensive loss. Net Loss per Share The Company calculates basic net loss per share by dividing net loss by the weighted average number of shares of common stock outstanding during the period. Diluted net loss per share is computed by giving effect to all potential dilutive common stock equivalents outstanding during the period. For purposes of this calculation, options to purchase common stock and common stock warrants are considered common stock equivalents. Potential common shares that have an anti-dilutive effect (i.e., those that increase income per share or decrease loss per share) are excluded from the calculation of diluted net loss per share. The following outstanding stock options, warrants, and RSUs to purchase common stock were excluded from the computation of diluted net loss per share for the periods presented because including them would have had an anti-dilutive effect: Year Ended December 31, 2021 2020 2019Common stock warrants — 612,310 167,847Common stock options 5,996,813 5,039,194 3,749,186Restricted stock units — 111,305 222,606Total 5,996,813 5,762,809 4,139,639 Segment and Geographical Information The Company operates in one segment and reports segment information in accordance with ASC 280, Segment Reporting. Management uses one measurement of profitability and does not segregate its business for internal reporting, however in making certain operating decisions and assessing performance, management will additionally review the disaggregated revenue results by product and geography. As of December 31, 2021 and 2020, 100% of long-lived assets were in the United States. Revenue is attributed to a geographic region based on the location of the end customer. See Note 10 for details of revenue by product and geography. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (ASU) No. 2014-09, Revenue from Contracts with Customers, requiring an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. This updated standard became effective for the Company in the first quarter of fiscal year 2018. The Company began to recognize revenue in 2021 using this updated standard. See Note 9 for additional details of the revenue recognition approach. In November 2018, the FASB issued ASU No. 2018-18 Collaborative Arrangements – Clarifying the Interaction between Topic 808 (Collaborative Arrangements) and Topic 606 (Revenue from Contracts with Customers), which clarifies the interaction between ASC 808, Collaborative Arrangements and ASC 606, Revenue from Contracts with Customers (“ASC 606”). The ASU clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC 606 when the counterparty is a customer. In addition, the ASU precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue if the counterparty is not a customer for that transaction. The Company adopted the standard on January 1, 2020, however, did not record revenue until August 2021 and does not currently have any collaborative arrangements in place. The adoption of the new standard had no impact on the Company’s consolidated financial statements. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which eliminates certain exceptions related to the general principles in ASC 740 and makes amendments to other areas with the intention of simplifying various aspects related to accounting for income taxes. The new standard is effective for fiscal years beginning after December 15, 2020, including interim periods therein; with early adoption permitted. The Company adopted the Topic 740 effective January 1, 2021. The adoption did not have a material impact on the Company’s financial statements.