NeuroPace (NPCE) 10-Q 3 Jun 21 2021 Q1 Quarterly report Financial data

Cover

Cover - shares	3 Months Ended
	Mar. 31, 2021	Jun. 03, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-40337
Entity Registrant Name	NEUROPACE, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	22-3550230
Entity Address, Address Line One	455 N. Bernardo Avenue
Entity Address, City or Town	Mountain View
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94043
City Area Code	650
Local Phone Number	237-2700
Title of 12(b) Security	Common Stock, $0.001 par value per share
Trading Symbol	NPCE
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		24,291,134
Amendment Flag	false
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001528287
Current Fiscal Year End Date	--12-31

Condensed Balance Sheets

Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 13,841	$ 26,390
Short-term investments	16,689	11,689
Accounts receivable	8,202	8,395
Inventory	7,042	6,909
Prepaid expenses and other current assets	1,314	1,179
Total current assets	47,088	54,562
Property and equipment, net	476	515
Restricted cash	366	366
Deferred offering costs	2,371	484
Other assets	23	23
Total assets	50,324	55,950
Current liabilities
Accounts payable	1,484	949
Accrued liabilities	5,734	6,603
Short-term debt	3,590	2,043
Total current liabilities	10,808	9,595
Deferred rent, noncurrent	1,204	1,301
Long-term debt	49,561	50,821
Redeemable convertible preferred stock warrant liability	3,491	369
Other liabilities	274	274
Total liabilities	65,338	62,360
Commitments and contingencies (Note 5)
Redeemable convertible preferred stock, $0.001 par value - 60,757,386 shares authorized as of March 31, 2021 and December 31, 2020; 16,614,178 shares issued and outstanding as of March 31, 2021 and December 31, 2020 (Liquidation value $227,755 as of March 31, 2021 and December 31, 2020)	141,422	141,422
Stockholders’ deficit
Common stock, $0.001 par value - 74,636,348 shares authorized as of March 31, 2021 and December 31, 2020; 470,634 and 314,096 shares issued and outstanding as of March 31, 2021 and December 31, 2020, respectively	0	0
Additional paid-in capital	240,032	239,826
Accumulated other comprehensive income	33	33
Accumulated deficit	(396,501)	(387,691)
Total stockholders’ deficit	(156,436)	(147,832)
Total liabilities, redeemable convertible preferred stock and stockholders’ deficit	$ 50,324	$ 55,950

Condensed Balance Sheets (Paren

Condensed Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Redeemable convertible preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized (in shares)	60,757,386	60,757,386
Redeemable convertible preferred stock, shares issued (in shares)	16,614,178	16,614,178
Redeemable convertible preferred stock, shares outstanding (in shares)	16,614,178	16,614,178
Redeemable convertible preferred stock, liquidation preference	$ 227,755	$ 227,755
Common stock par value (in dollars per share)	$ 0.001	$ 0.001
Common stock authorized (in shares)	74,636,348	74,636,348
Common stock outstanding (in shares)	470,634	314,096
Common stock issued (in shares)	470,634	314,096

Condensed Statements of Operati

Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Revenue	$ 11,217	$ 9,975
Cost of goods sold	2,724	2,918
Gross profit	8,493	7,057
Operating expenses
Research and development	4,100	4,833
Selling, general and administrative	8,267	7,682
Total operating expenses	12,367	12,515
Loss from operations	(3,874)	(5,458)
Interest expense (includes $0 and $461 to related parties in the three months ended March 31, 2021 and 2020, respectively)	(1,849)	(2,998)
Other income (expense), net	(3,087)	1,715
Net loss	(8,810)	(6,741)
Unrealized loss on available-for-sale debt securities	0	(41)
Comprehensive loss	$ (8,810)	$ (6,782)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (32.73)	$ (33.32)
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (32.73)	$ (33.32)
Weighted-average common stock outstanding used to compute diluted net loss per share (in shares)	269,178	202,341
Weighted-average common stock outstanding used to compute basic net loss per share (in shares)	269,178	202,341

Condensed Statements of Opera_2

Condensed Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
Interest expense, related party	$ 0	$ 461

Condensed Statements of Redeema

Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders’ Deficit - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2019	635,048
Beginning balance at Dec. 31, 2019	$ 73,568
Ending balance (in shares) at Mar. 31, 2020	635,048
Ending balance at Mar. 31, 2020	$ 73,568
Beginning balance (in shares) at Dec. 31, 2019		202,121
Beginning balance at Dec. 31, 2019	(129,350)	$ 0	$ 234,290	$ 1	$ (363,641)
Increase (Decrease) in Stockholders' Equity
Net loss	(6,741)				(6,741)
Unrealized loss on available-for-sale debt securities	(41)			(41)
Issuance of common stock pursuant to stock option exercises (in shares)		131
Issuance of common stock pursuant to stock option exercises	6		6
Stock-based compensation	301		301
Ending balance (in shares) at Mar. 31, 2020		202,252
Ending balance at Mar. 31, 2020	$ (135,825)	$ 0	234,597	(40)	(370,382)
Beginning balance (in shares) at Dec. 31, 2020	16,614,178
Beginning balance at Dec. 31, 2020	$ 141,422
Ending balance (in shares) at Mar. 31, 2021	16,614,178
Ending balance at Mar. 31, 2021	$ 141,422
Beginning balance (in shares) at Dec. 31, 2020	314,096	314,096
Beginning balance at Dec. 31, 2020	$ (147,832)	$ 0	239,826	33	(387,691)
Increase (Decrease) in Stockholders' Equity
Net loss	$ (8,810)				(8,810)
Issuance of common stock pursuant to stock option exercises (in shares)	156,538	156,538
Issuance of common stock pursuant to stock option exercises	$ 4		4
Stock-based compensation	$ 202		202
Ending balance (in shares) at Mar. 31, 2021	470,634	470,634
Ending balance at Mar. 31, 2021	$ (156,436)	$ 0	$ 240,032	$ 33	$ (396,501)

Condensed Statements of Cash Fl

Condensed Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flows from operating activities
Net loss	$ (8,810)	$ (6,741)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation expense	202	301
Depreciation	74	82
Amortization of debt discount and issuance costs	69	72
Non-cash interest expense	217	1,560
PIK interest incurred but not paid on term loan	0	1,350
Inventory write-downs	24	97
Realized loss from sale of short-term investments	0	15
Change in fair value of redeemable convertible preferred stock warrant liability	3,122	0
Change in fair value of derivative instrument	0	(1,705)
Changes in operating assets and liabilities
Accounts receivable	194	(197)
Inventory	(157)	349
Prepaid expenses and other assets	(135)	144
Accounts payable	536	(109)
Accrued liabilities	(1,094)	(1,692)
Deferred rent	(178)	(74)
Net cash (used in) operating activities	(5,936)	(6,548)
Cash flows from investing activities
Acquisition of property and equipment	(35)	(16)
Proceeds from sale of short-term investments	0	6,300
Purchase of short-term investments	(5,000)	(6,755)
Net cash (used in) investing activities	(5,035)	(471)
Cash flows from financing activities
Issuance of common stock pursuant to stock option exercises	4	6
Payment of deferred offering costs	(1,582)	0
Issuance of convertible notes, net of issuance costs (includes $0 and $11,867 from related parties in the three months ended March 31, 2021 and 2020, respectively)	0	12,514
Net cash (used in) provided by financing activities	(1,578)	12,520
Net (decrease) increase in cash and cash equivalents	(12,549)	5,501
Cash, cash equivalents and restricted cash
Beginning of the period	26,756	4,123
End of the period	14,207	9,624
Reconciliation of cash, cash equivalents and restricted cash to balance sheets:
Cash, cash equivalents and restricted cash in balance sheets	14,207	9,624
Supplemental disclosure of cash flow information:
Cash paid for interest	1,563	0
Supplemental disclosures of non-cash investing and financing information:
Deferred offering costs	$ 578	$ 0

Condensed Statements of Cash _2

Condensed Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Cash Flows [Abstract]
Proceeds from related party debt	$ 0	$ 11,867

The Company

The Company	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company	The Company NeuroPace, Inc., or the Company, was incorporated in the state of Delaware on November 19, 1997. The Company is a commercial-stage medical device company that has developed the RNS System, a brain-responsive neuromodulation system designed for treating medically refractory focal epilepsy by delivering personalized, real-time treatment at the seizure source. The Company began commercializing its products in the United States in 2014. Initial Public Offering On April 21, 2021, the Company’s registration statement on Form S-1 (File No. 333-254663) relating to its initial public offering, or IPO, of common stock became effective. The IPO closed on April 26, 2021, at which time the Company issued 6,900,000 shares of its common stock at a price of $17.00 per share, which included the issuance of shares in connection with the exercise by the underwriters of their option to purchase up to 900,000 additional shares (see Note 14). The Company received an aggregate of $117.3 million gross proceeds, before underwriting discounts and commissions and offering costs, and approximat ely $105.2 million i n net proceeds after deducting underwriting discounts and commissions and estimated offering costs. Upon the closing of the IPO, all outstanding shares of the Company’s redeemable convertible preferred stock converted into 16,614,178 shares of common stock, warrants to purchase 346,823 shares of Series B’ convertible preferred stock net exercised to 213,941 shares of Series B’ convertible preferred stock and subsequently converted into common stock on a one-to-one basis, and warrants to purchase 219 shares of common stock net exercised to 185 shares of common stock. In connection with the completion of its IPO, on April 26, 2021, the Company’s certificate of incorporation was amended and restated to provide for 200,000,000 authorized shares of common stock with a par value of $0.001 per share and 10,000,000 authorized shares of preferred stock with a par value of $0.001 per share. The unaudited interim condensed financial statements as of March 31, 2021, including share and per share amounts, do not give effect to the IPO, as it closed subsequent to March 31, 2021. Liquidity and Capital Resources The Company has incurred operating losses and negative cash flows from operations since its inception. For the three months ended March 31, 2021 and 2020, net loss was $8.8 million and $6.7 million and cash used in operations was $5.9 million and $6.5 million, respectively. As of March 31, 2021, accumulated deficit was $396.5 million and cash, cash equivalents and short-term investments was $30.5 million. Through March 31, 2021, the Company has funded its operations principally through the sales of its products, issuance of redeemable convertible preferred stock and debt financing. On April 26, 2021, the Company completed an IPO in which the Company issued and sold 6,900,000 shares of its common stock, which includes 900,000 shares issued and sold pursuant to the exercise of the underwriters’ option to purchase additional shares, at a public offering price of $17.00 per share, for aggregate gross proceeds of $117.3 million. The Company received approximately $105.2 million in net proceeds after deducting underwriting discounts and commissions and estimated offering costs. The Company’s condensed financial statements have been prepared on the basis of the Company continuing as a going concern for the next 12 months. Management believes that the Company’s cash, cash equivalents and short-term investments as of March 31, 2021 , together with the net proceeds from the IPO, will allow the Company to continue its planned operations for at least the next 12 months from the date of the issuance of these unaudited interim condensed financial statements. In connection with the New Term Loan described in Note 6, the Company will need to be in compliance with a minimum annual net revenue covenant determined in accordance with generally a ccepted accounting principles beginning in the year ended December 31, 2021 of $43.0 million and maintain a minimum cash and cash equivalents balance of $5.0 million after the completion of the IPO. If the Company cannot generate sufficient revenue in the future, the Company may not be in compliance with the annual net revenue covenant and the lender may call the debt resulting in the Company immediately needing additional funds. The COVID-19 pandemic and the resulting economic downturn are affecting business conditions in the industry in which the Company operates. Beginning in March 2020, the Company’s net sales were negatively impacted by the COVID-19 pandemic as hospitals delayed or canceled elective procedures. In response to the pandemic, many

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The unaudited interim condensed financial statements have been prepared in conformity with generally accepted accounting principles in the United States, or GAAP, as defined by the Financial Accounting Standards Board, or the FASB. Reverse Stock Split On August 18, 2020, the Company effected a 1-for-100 reverse stock split of its common stock and redeemable convertible preferred stock. Upon the effectiveness of the reverse stock split, all issued and outstanding shares of common stock and redeemable convertible preferred stock and related per share amounts contained in the accompanying financial statements were retroactively revised to reflect this reverse stock split for all periods presented. The par value of the authorized stock was not adjusted as a result of the reverse stock split. On April 9, 2021, the Company effected a 1-for-2.6 reverse stock split of its common stock and redeemable convertible preferred stock. All issued and outstanding shares of common stock and redeemable convertible preferred stock and related per share amounts contained in the accompanying financial statements have been retroactively revised to reflect this reverse stock split for all periods presented. The par value of the authorized stock was not adjusted as a result of the reverse stock split. Unaudited Interim Financial Information The condensed balance sheet as of December 31, 2020 was derived from the Company’s audited financial statements, but does not include all disclosures required by GAAP. The accompanying unaudited condensed financial statements as of March 31, 2021 and for the three months ended March 31, 2021 and 2020, have been prepared by the Company, pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC, for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2020 and notes thereto, included in the Company’s final prospectus for the IPO filed with the SEC pursuant to Rule 424(b)(4) on April 23, 2021, or the final prospectus. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair statement of the Company’s condensed financial position as of March 31, 2021 and condensed results of operations and cash flows for the three months ended March 31, 2021 and 2020 have been made. The results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2021. Use of Estimates The preparation of unaudited interim condensed financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. The Company uses significant judgment when making estimates related to the valuation of its common stock and related stock-based compensation, the valuation of deferred tax assets and related valuation allowances, provision for excess and obsolete inventories, the valuation of derivative financial instruments and redeemable convertible preferred stock warrant liability. The Company bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Although these estimates are based on the Company’s knowledge of current events and actions it may undertake in the future, actual results may ultimately materially differ from these estimates and assumptions. Fair Value of Financial Instruments Carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts receivable, accounts payable and accrued liabilities, approximate fair value because of the short-term nature of these instruments. Short-term investments comprise available-for-sale debt securities, which are carried at fair value. The Company believes that its borrowings bear interest at the prevailing market rates for instruments with similar characteristics; accordingly, the carrying value of this instrument approximates its fair value. Derivative instruments and the redeemable convertible preferred stock warrant liability are carried at fair value based on unobservable market inputs. The Company determines the fair value of financial and non-financial assets and liabilities using the fair value hierarchy which establishes three levels of inputs that may be used to measure fair value (see Note 3). Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents, short-term investments and accounts receivable to the extent of the amounts recorded on the balance sheet. The Company’s cash is invested in one major financial institution in the United States. Deposits in this financial institution may exceed federally insured limits. The Company’s cash equivalents are invested in money market funds. The Company’s accounts receivable are due from a variety of health care organizations in the United States. For the three months ended March 31, 2021 and 2020, there were no customers that represented 10% or more of revenue. As of March 31, 2021 and December 31, 2020, no customer represented 10% or more of the Company’s accounts receivable. The Company is subject to certain risks, including that its devices may not be approved or cleared for marketing by governmental authorities or be successfully marketed for expanded indications. There can be no assurance that the Company’s products will achieve widespread adoption in the marketplace, nor can there be any assurance that existing devices or any future devices can be developed or manufactured at an acceptable cost and with appropriate performance characteristics. The Company is also subject to risks common to companies in the medical device industry, including, but not limited to, new technological innovations, dependence upon third-party payors to provide adequate coverage and reimbursement, dependence on key personnel, single-source suppliers and vendors in connection with the manufacture of its products, concentration of Level 4 CECs, obtaining, maintaining, protecting, enforcing, and defending intellectual property rights and proprietary technology, product liability claims, and compliance with government regulations. The Company’s medical devices require approvals or clearances from the U.S. Food and Drug Administration, or the FDA, or international regulatory agencies. In addition, in order to continue the Company’s operations, compliance with various federal and state laws is required. If approvals or clearances were withdrawn by the FDA for the Company’s current products or if such approvals or clearances were denied or delayed for future products, product updates, or expanded indications for use, it would have a material adverse impact on the Company. Deferred Offering Costs The Company capitalizes, within other assets, certain legal, accounting and other third-party fees that are directly related to the Company’s in-process equity financings, including its initial public offering, until such financings are consummated. After consummation of the equity financing, these costs are recorded as a reduction of the proceeds received as a result of the offering. Should a planned equity financing be abandoned, terminated or significantly delayed, the deferred offering costs are immediately written off to operating expenses. As of March 31, 2021 and December 31, 2020, $2.4 million and $0.5 million of deferred offering costs were recorded on the condensed balance sheets, respectively. Upon closing the IPO, all deferred offering costs were charged against the proceeds from the IPO and recorded in stockholders equity (deficit) as a reduction of additional paid-in capital. Net Loss per Share Attributable to Common Stockholders Basic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, redeemable convertible preferred stock, stock options, common stock subject to repurchase related to early exercise of stock options, and convertible notes are considered to be potentially dilutive securities. Basic and diluted net loss attributable to common stockholders per share is presented in conformity with the two-class method required for participating securities, as the redeemable convertible preferred stock is considered a participating security because it participates in dividends with common stock. The Company also considers the shares issued upon the early exercise of stock options subject to repurchase to be participating securities, because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. The holders of redeemable convertible preferred stock and the holders of the shares issued upon early exercise of stock options subject to repurchase do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders. Because the Company has reported a net loss for all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods. Recent Accounting Pronouncements Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02 (Topic 842), Leases . ASU 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. This ASU provides a lessee with an option to not account for leases with a term of 12 month or less as leases in the scope of this ASU. This ASU will also require new qualitative and quantitative disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. This ASU should be applied through a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements , which allows entities to elect an optional transition method where entities may continue to apply the existing lease guidance during the comparative periods and apply the new lease requirements through a cumulative effect adjustment in the period of adoption rather than in the earliest period presented. In June 2020, the FASB issued ASU 2020-05, Revenue from Contracts with Customers (Topic 606) and Leases (Topic 842): Effective Dates for Certain Entities, which delays the adoption dates for ASU 2016-02 for non-public entities to fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022. Early adoption is allowed. The Company expects to recognize a right-of-use asset and corresponding lease liability for its real estate operating leases upon adoption, expecting to use the modified retrospective approach for the adoption of this ASU. In June 2016, the FASB issued ASU 2016-13, Financial Instruments- Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which amends existing guidance on the impairment of financial assets and adds an impairment model that is based on expected losses rather than incurred losses and requires an entity to recognize as an allowance its estimate of expected credit losses for its financial assets. An entity will apply this guidance through a cumulative-effect adjustment to retained earnings upon adoption (a modified-retrospective approach) while a prospective transition approach is required for debt securities for which an other-than-temporary impairment had been recognized before the effective date. For public business entities that meet the definition of an SEC filer, excluding entities eligible to be smaller reporting companies as defined by the SEC, adoption is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. For SEC filers that are eligible to be smaller reporting companies and for all other entities, this ASU is effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. Early adoption is permitted. The Company is in the process of evaluating the impact of the adoption on its financial statements and related disclosures. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting . The amendments in ASU 2020-04 provide optional expedients and exceptions for applying generally accepted accounting principles to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments in this ASU are effective for all entities as of March 12, 2020 through December 31, 2022. An entity may elect to apply the amendments for contract modifications by Topic or Industry Subtopic as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The Company is currently evaluating the impact of the adoption of this ASU on the Company’s financial statements and related disclosures. In August 2020, the FASB issued ASU 2020-06, Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity . This ASU simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. Specifically the ASU removes: i) major separation models required under GAAP and ii) certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception, which will permit more equity contracts to qualify for the exception. For public business entities that meet the definition of an SEC filer, excluding entities eligible to be smaller reporting companies as defined by the SEC, this ASU is effective for interim and annual reporting periods beginning after December 15, 2021. For all other entities, the amendments are effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of this ASU on the Company’s financial statements and related disclosures.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1 Quoted prices in active markets for identical assets or liabilities. Level 2 Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. The Company utilizes the market approach to measure fair value for its financial assets and liabilities. The market approach uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities. The following table summarizes the Company’s financial assets (cash equivalents, marketable securities and liabilities) at fair value as of March 31, 2021 (in thousands): Fair Value as of March 31, 2021 Basis for Fair Value Measurements (Level 1) (Level 2) (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 5,088 $ 5,088 $ — $ — Fixed income mutual funds, included in short-term investments 16,689 16,689 — — Total $ 21,777 $ 21,777 $ — $ — Liabilities: Redeemable convertible preferred stock warrant liability 3,491 — — 3,491 Total $ 3,491 $ — $ — $ 3,491 The following table summarizes the Company’s financial assets (cash equivalents, marketable securities and liabilities) at fair value as of December 31, 2020 (in thousands): Fair Value as of December 31, 2020 Basis for Fair Value Measurements (Level 1) (Level 2) (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 5,062 $ 5,062 $ — $ — Fixed income mutual funds, included in short-term investments 11,689 11,689 — — Total $ 16,751 $ 16,751 $ — $ — Liabilities: Redeemable convertible preferred stock warrant liability 369 — — 369 Total $ 369 $ — $ — $ 369 The money market funds are highly liquid and primarily invest in short-term fixed income securities issued by the U.S. government and U.S. government agencies. The Company’s available-for-sale investments comprise short- term investments in fixed income mutual funds, which primarily consist of debt securities issued by the U.S. government and U.S. government agencies and corporate bonds and notes. The following is a summary of the Company’s available-for-sale debt securities (in thousands): March 31, December 31, 2021 2020 Cost basis $ 16,656 $ 11,656 Unrealized gain 33 33 Fair value $ 16,689 $ 11,689 The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial instruments (in thousands): Redeemable Convertible Preferred Stock Warrant Liability Fair value as of January 1, 2021 $ 369 Change in fair value included in other income (expense), net 3,122 Fair value as of March 31, 2021 $ 3,491 Derivative Instrument Fair value as of January 1, 2020 $ 4,719 Recognition of derivative instrument related to 2020 Convertible Notes 1,669 Change in fair value included in other income (expense), net (1,705) Fair value as of March 31, 2020 $ 4,683 The fair value of the derivative instrument has been estimated at the date of inception and at the subsequent balance sheet date using a two-step approach to valuation, employing a probability-weighted scenario valuation method and then comparing the instrument’s value with-and-without the derivative features in order to estimate their combined fair value, using unobservable inputs, which are classified as Level 3 within the fair value hierarchy. In August 2020, the derivative instrument was extinguished in connection with the issuance of Series B’ redeemable convertible preferred stock and conversion of all outstanding convertible notes and accrued unpaid interest into shares of Series B’ redeemable convertible preferred stock. In determining the fair value of the redeemable convertible preferred stock warrant liability, the Company used the Black-Scholes option pricing model to estimate the fair value using unobservable inputs including the expected term, expected volatility, risk-free interest rate and dividend yield (see Note 8).

Balance Sheet Components

Balance Sheet Components	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Balance Sheet Components	Balance Sheet Components Inventory Inventories consist of the following (in thousands): March 31, December 31, 2021 2020 Raw materials $ 1,823 $ 1,721 Work-in-process 1,532 1,487 Finished goods 3,687 3,701 Total $ 7,042 $ 6,909 Property and Equipment, net Property and equipment, net consists of the following (in thousands): March 31, December 31, 2021 2020 Machinery, equipment, furniture and fixtures $ 3,544 $ 3,544 Computer equipment and software 2,765 2,730 Leasehold improvements 2,402 2,402 8,711 8,676 Less: Accumulated depreciation (8,235) (8,161) Property and equipment, net $ 476 $ 515 Depreciation expense for the three months ended March 31, 2021 and 2020 was $0.1 million and $0.1 million, respectively. Accrued Liabilities Accrued liabilities consist of the following (in thousands): March 31, December 31, 2021 2020 Payroll and related expenses $ 3,708 $ 4,565 Inventory-raw materials 471 636 Professional fees 641 279 Deferred rent, current 585 666 Clinical trials 36 107 Other 293 350 $ 5,734 $ 6,603

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Facility Lease In August 2011, the Company entered into a non-cancelable operating lease for combined office and manufacturing facilities in Mountain View, California. The lease was scheduled to expire in April 2019 and was amended in May 2018 to extend it through June 2024. The terms of the facility lease provide for rental payments on a graduated scale; however, rent expense is recognized on a straight-line basis over the lease term. The Company has an option to extend the lease for a period of five Rental payments range from $2.9 million to $3.3 million per year over the extended term of the lease. In April 2020, the Company amended the lease agreement to defer 50.0% of the rental payment for May and June 2020 of $0.3 million. The deferred rental payments accrue interest at an annual rate of 8.0% starting from October 1, 2020 and will be payable in three equal monthly installments commencing on April 1, 2021. Rent expense for the three months ended March 31, 2021 and 2020 was $0.7 million and $0.7 million, respectively. As of March 31, 2021 and December 31, 2020, $1.8 million and $2.0 million was recorded as deferred rent expense, respectively. The Company’s future payments under the non-cancellable operating lease (in thousands) are as follows: March 31, 2021 (remaining nine months) $ 2,632 2022 3,172 2023 3,267 2024 1,666 Total $ 10,737 Indemnifications In the normal course of business, the Company enters into contracts and agreements that contain a variety of representations and warranties and may provide for indemnification of the counterparty. The Company’s exposure under these agreements is unknown because it involves claims that may be made against it in the future but have not yet been made. To date, the Company has not been subject to any claims or been required to defend any action related to its indemnification obligations. The Company indemnifies each of its directors and officers for certain events or occurrences, subject to certain limits, while the director or officer is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with its certificate of incorporation and bylaws. The term of the indemnification period lasts as long as the director or officer may be subject to any proceeding arising out of acts or omissions of such individual in such capacity. The maximum amount of potential future indemnification is unlimited. The Company believes that the fair value of these indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations as of March 31, 2021 and December 31, 2020. Contingencies From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made and such expenditures can be reasonably estimated. The Company determined that no accrual was required as of March 31, 2021 and December 31, 2020. Legal Proceedings From time to time, the Company may become involved in legal proceedings arising from the ordinary course of its business. The Company may also pursue litigation to assert its legal rights and such litigation may be costly and divert the efforts and attention of its management and technical personnel which could adversely affect its business. The Company is currently not aware of any matters that could have a material adverse effect on its financial position, results of operations or cash flows.

Debt

Debt	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Debt	Debt 2014 Term Loan In November 2014, the Company entered into a Term Loan Agreement, as amended, for total borrowings of up to $40.0 million with Capital Royalty Partners II L.P. and its affiliates Capital Royalty Partners II – Parallel Fund “A” L.P. and Parallel Investment Opportunities Partners II L.P., or collectively, CRG. As of December 31, 2019, $40.0 million had been funded under this Term Loan Agreement, or the Term Loan. The Term Loan bore interest at a rate of 12.5% per annum based on a 360-day year and actual days elapsed. Payments under the Term Loan were to be made quarterly with payment dates fixed at the end of each calendar quarter, or the Payment Dates. Through September 30, 2017, the Company had the option to pay interest as follows: 8.0% per annum paid in cash and 4.5% per annum paid-in-kind, or PIK, by increasing the principal of the Term Loan. On each Payment Date through September 30, 2016, the Company elected the PIK option, issuing PIK notes totaling $2.7 million. On each Payment Date from December 31, 2016 through December 31, 2019, the Company paid all interest due in cash. The Term Loan was interest-only through September 30, 2019. Following the interest-only period, principal payments were to be made in equal installments at the end of the next four calendar quarters, with the final payment due on September 30, 2020. The Term Loan included a fee upon repayment of the loan equal to 5% of the aggregate principal amount being prepaid or repaid. The Company ratably accreted the fee over the life of the loan. In connection with the Term Loan, the Company paid total closing fees of $0.8 million and issued warrants to purchase 219 shares of its Series I redeemable convertible preferred stock at $1,866.80 per share. The initial fair value of the warrants was $0.3 million and resulted in a discount to the Term Loan, which was amortized to interest expense over the life of the loan using the effective interest method. Prior to 2019, these warrants were modified to be exercisable for 219 shares of common stock at $2.60 per share, all of which remain outstanding as of March 31, 2021. Upon the closing of the IPO, warrants to purchase 219 shares of common stock net exercised to 185 shares of common stock. In October 2019, the Term Loan Agreement was amended to extend the interest-only period through December 31, 2019. This amendment was accounted as a debt modification and the impact on the Term Loan’s effective interest rate was a decrease from 15.0% to 14.7%. In February through June 2020, the Term Loan Agreement was amended to extend the interest-only period through June 30, 2020 and to allow the Company to pay such interest entirely in kind by adding it to the aggregate principal of the loan. The Company paid $1.4 million in interest due on March 31, 2020 in kind and paid $1.4 million interest due on June 30, 2020 in cash. The amendments were accounted as a debt modification and the Term Loan’s effective interest rate was changed within 14.7% to 14.2% with each amendment. The Term Loan was collateralized by substantially all of the Company’s assets. The Term Loan Agreement contained customary representations and warranties, covenants, events of default and termination provisions. The affirmative covenants included, among other things, that the Company achieve minimum annual revenue thresholds and maintain a minimum balance of cash and cash equivalents. In September 2020, the Company repaid its entire obligation under the Term Loan amounting to $47.6 million, including principal of $44.1 million, interest of $1.3 million and fees of $2.2 million, using the proceeds from New Term Loan (as defined below). The repayment of the Term Loan was accounted for as a debt extinguishment, which resulted in an immaterial extinguishment loss. 2020 Term Loan In September 2020, the Company entered into a new Term Loan Agreement with CRG Partners IV L.P. and its affiliates for total borrowings of up to $60 million, or the New Term Loan, and borrowed $50 million. The remaining $10.0 million of the New Term Loan will be available to the Company for borrowing until March 31, 2022 if the Company achieves a revenue-based milestone in 2021. The New Term Loan bears interest at a rate of 12.5% per year. Payments under the New Term Loan are made quarterly with payment dates fixed at the end of each calendar quarter. The New Term Loan was interest-only through September 30, 2023, which could be extended through September 30, 2025 at Company’s option if the Company completed its IPO on or prior September 30, 2023. In connection with closing the IPO, the Company extended the interest-only period to September 30, 2025. Following the interest-only period, principal payment is due in one installment on September 30, 2025. The New Term Loan includes a fee upon repayment of the loan equal to 10% of the aggregate principal amount being prepaid or repaid. As of March 31, 2021, the New Term Loan had an annual effective interest rate of 16.08% per year. The New Term Loan is collateralized by substantially all of the Company’s assets. The New Term Loan Agreement contains customary representations and warranties, covenants, events of default and termination provisions. The financial covenants require that the Company achieve minimum annual revenue thresholds commencing in 2021 and maintain a minimum balance of cash and cash equivalents (see Note 1). The Company paid $1.0 million in fees to the lender and third parties which is reflected as a discount on the loan and is being accreted over the life of the loan using the effective interest method. Also, the Company issued warrants to the lender for a total of 346,823 shares of Series B’ redeemable convertible preferred stock. The warrants had a fair value of $0.6 million as of the issuance date, which was accounted as debt issuance costs (see Note 8). During the three months ended March 31, 2021, the Company recorded interest expense related to deferred financing and debt issuance costs of the New Term Loan of $0.1 million. Interest expense on the New Term Loan was $1.8 million during the three months ended March 31, 2021. Paycheck Protection Program In April 2020, the Company received $4.0 million from a federal Small Business Administration loan under the Paycheck Protection Program, or the PPP Loan. The note bears interest at 1.0% per year on the outstanding principal amount and matures 24 months from the date of the note. No payments were due for the six-month period beginning on the date of the note. Payments of principal and interest were due over the following 18 months. The Small Business Administration modified the PPP Loan such that monthly payments of principal and interest are due from September 2021 through April 2022. As of March 31, 2021, the Company did not make any repayments of the PPP Loan. In April 2021, the Company repaid its entire obligation under the PPP Loan amounting to $4.1 million, including principal of $4.0 million and interest of less than $0.1 million, using the proceeds from its IPO. As of March 31, 2021, future minimum payments for the New Term Loan and PPP Loan are as follows (in thousands): New Term Loan PPP Loan 2021 (remaining nine months) $ 4,774 $ 2,060 2022 6,337 2,060 2023 12,587 — 2024 29,364 — 2025 24,931 — Total 77,993 4,120 Less: Unamortized debt discount and issuance cost (1,360) — Less: Unaccreted backend fee (4,577) — Less: Interest (22,993) (32) Total future minimum payments $ 49,063 $ 4,088 2019 and 2020 Convertible Notes In March and September 2019, Company issued convertible notes to certain investors for aggregate proceeds of $21.3 million, or the 2019 Convertible Notes. In January and March 2020, the Company raised $7.1 million and $5.4 million, respectively, through the sale and issuance of additional convertible notes, or the 2020 Convertible Notes. The 2019 and 2020 Convertible Notes were subordinated to the Term Loan, bore interest on the outstanding principal amount at the rate of 8.0% per annum, and had a maturity date of December 31, 2020. Upon the consummation of an equity financing with aggregate proceeds to the Company of not less than $18 million, or the Qualified Financing, the outstanding principal balance of the 2019 and 2020 Convertible Notes and accrued but unpaid interest would convert into shares of capital stock issued in such Qualified Financing at a conversion price equal to 85% of the issuance price per share of such capital stock in such Qualified Financing. In the event the Company consummated, while the 2019 and 2020 Convertible Notes remained outstanding, an equity financing that did not constitute a Qualified Financing, then the majority holders had the option to treat such equity financing as a Qualified Financing. If the Company did not complete a Qualified Financing prior to the maturity date while the 2019 and 2020 Convertible Notes remained outstanding, the holders of the notes could elect to convert the outstanding principal and unpaid accrued interest into the Company’s Series A’ redeemable convertible preferred stock at a conversion price of $116.35 per share. Upon the occurrence of a change of control, the 2019 and 2020 Convertible Notes would upon the election of the majority holders either (i) become due and payable upon the closing of such change of control in cash in an amount equal to (a) the outstanding principal amount plus any unpaid accrued interest, plus (b) a repayment premium equal to 100% of the outstanding principal amount, or (ii) be converted such that the outstanding principal balance of the notes and any unpaid accrued interest would convert into shares of the Company’s Series A’ redeemable convertible preferred stock at a conversion price equal to $116.35 per share. The 2019 and 2020 Convertible Notes contained embedded derivative instruments, including automatic conversion into equity securities upon completion of a Qualified Financing, that were required to be bifurcated and accounted for separately as a single derivative instrument initially and subsequently measured at fair value with the change in fair value recorded in other income (expense), net in the statements of operations and comprehensive loss. The issuance date estimated fair values of the derivative instruments issued with the March and September 2019 notes were $4.1 million and $1.9 million, respectively, which were recorded as debt discounts. The issuance date estimated fair values of the derivative instruments issued with the January and March 2020 notes were $1.0 million and $0.7 million, respectively, which were recorded as debt discounts. In August 2020, the derivative instrument was extinguished in connection with the issuance of Series B’ redeemable convertible preferred stock. The discount on the 2019 and 2020 Convertible Notes was amortized over the contractual term ending on December 31, 2020, using the effective interest method. The annual effective interest rate was estimated from 10.8% to 12.2% per year. The interest expense for the three months ended March 31, 2020 was $1.4 million, consisting of $0.9 million of contractual interest expense and $0.5 million amortization of debt discount arising from separation of the embedded derivative instrument. For the three months ended March 31, 2020, $10.3 million of convertible notes were issued to related parties, resulting in interest expense of $0.5 million. In connection with the sale and issuance of Series B’ redeemable convertible preferred stock all outstanding convertible notes were modified to remove the 15% discount on conversion. All outstanding convertible notes of $33.9 million and accrued unpaid interest of $2.5 million were converted into 8,379,410 shares of Series B’ redeemable convertible preferred stock at 100% of the preferred stock issuance price of $4.3423 per share. The conversion of the 2019 Convertible Notes and 2020 Convertible Notes into shares of Series B' redeemable convertible preferred stock was accounted for as a debt extinguishment with $4.1 million extinguishment gain recognized as a deemed capital contribution to additional paid-in capital in the quarter ended September 30, 2020, as the holders of the notes were existing stockholders of the Company.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Redeemable Convertible Preferred Stock	Redeemable Convertible Preferred StockIn August 2020, the Company amended its Certificate of Incorporation, pursuant to which the Company has two series of redeemable convertible preferred stock, designated as Series A’ and Series B’. In August 2020, the Company issued 7,599,720 shares of Series B’ redeemable convertible preferred stock at $4.3423 per share for gross proceeds of $33.0 million. In connection with the issuance of Series B’ redeemable convertible preferred stock, all outstanding convertible notes of $33.9 million and accrued unpaid interest of $2.5 million were converted into 8,379,410 shares of Series B’ redeemable convertible preferred stock at such price. As of March 31, 2021 and December 31, 2020, the redeemable convertible preferred stock comprises (in thousands, except per share and share amounts): Number of Shares Authorized Number of Shares Issued and Outstanding Carrying Amount Liquidation Value Original Issue Price Series A’ 1,651,154 635,048 $ 73,340 $ 36,945 $ 58.1750 Series B’ 59,106,232 15,979,130 $ 68,082 $ 190,810 $ 4.3423 60,757,386 16,614,178 $ 141,422 $ 227,755 On April 26, 2021, upon the closing of the Company’s IPO, all outstanding redeemable convertible preferred stock automatically converted into 16,614,178 shares of common stock. Prior to the closing of the Company’s IPO, the holders of redeemable convertible preferred stock had the following various rights and preferences: Dividends The holders of redeemable convertible preferred stock were entitled to receive dividends, out of any assets legally available therefore, prior and in preference to any declaration or payment of any dividend to the common stockholders, at the rate of $4.6540 per share per annum on each outstanding share of Series A’ redeemable convertible preferred stock and $0.3474 per share per annum on each outstanding share of Series B’ redeemable convertible preferred stock, payable when, as and if declared by the Board of Directors. Such dividends shall not be cumulative and if less than the full amount of dividends payable on the redeemable convertible preferred stock is declared and paid, any such payments would have been made ratably among the holders of the redeemable convertible preferred stock in proportion to the total amount each holder would be entitled to receive if the full amount of dividends payable on the redeemable convertible preferred stock had been declared. As of March 31, 2021 and December 31, 2020, no dividends had been declared. Liquidation In the event of any liquidation, dissolution or winding up of the Company, the holders of the Company’s Series B’ redeemable convertible preferred stock would have been entitled to receive, prior to any distribution of the Company’s assets to the holders of Series A’ redeemable convertible preferred stock and common stock, an amount per share equal to (i) as of and following August 19, 2020 (the “Initial Closing” of Series B’ redeemable convertible preferred stock), and prior to, at the Company’s election, the earlier of (a) the date the Company’s cash balance falls below $4.0 million and (b) March 31, 2022 (the “Deferred Closing”), 2.75 times $4.3423 per share for each share of Series B’ redeemable convertible preferred stock, and (ii) as of and following the date of the Deferred Closing, either (x) 2.75 times $4.3423 per share if the Company’s actual cash-burn between the Initial Closing and December 31, 2021 is 110% or less of the Company’s business plan cash-burn for such time period as approved by the Board of Directors, or (y) otherwise 3 times $4.3423, for each share of Series B’ redeemable convertible preferred stock, plus declared but unpaid dividends. If, upon the occurrence of such event, the assets and funds thus distributed among the holders of redeemable convertible preferred stock would have been insufficient to permit the payment to such holders of the full amounts, then the entire assets and funds of the Company legally available for distribution would have been distributed ratably among the holders of redeemable convertible preferred stock in proportion to the preferential amount each such holder is otherwise entitled to receive. After full payment to the holders of Series B’ redeemable convertible preferred stock, the holders of Series A’ redeemable convertible preferred stock would have been entitled to receive, prior to any distribution of the Company’s assets to the holders of common stock, an amount per share equal to $58.1750 per share for each share of redeemable convertible preferred stock plus declared but unpaid dividends. If, upon the occurrence of such event, the assets and funds thus distributed among the holders of redeemable convertible preferred stock would have been insufficient to permit the payment to such holders of the full amounts, then the entire assets and funds of the Company legally available for distribution would have been distributed ratably among the holders of redeemable convertible preferred stock in proportion to the preferential amount each such holder is otherwise entitled to receive. After the payment to the holders of redeemable convertible preferred stock of the full preferential amounts specified above, all of the remaining assets of the Company available for distribution to stockholders would have been distributed among the holders of Series B’ redeemable convertible preferred stock, Series A’ redeemable convertible preferred stock and common stock pro rata based on the number of shares of common stock held by each such holder, treating for this purpose all shares of redeemable convertible preferred stock as if converted to common stock prior to such liquidation, dissolution or winding up of the Company. Conversion The Company’s redeemable convertible preferred stock is convertible into shares of common stock at the option of a holder on a one-for-one basis with the conversion ratio subject to standard antidilutive adjustments, such as stock splits, stock dividends, combinations, subdivisions, recapitalizations or the like. The initial conversion price was $4.3423 and $58.1750 per share of Series B’ and Series A’ redeemable convertible preferred stock, respectively. Each share of Series A’ redeemable convertible preferred stock is convertible into shares of common stock immediately upon the date specified by written consent or written agreement of the holders of a majority of the outstanding shares of Series A’ redeemable convertible preferred stock. Each share of Series B’ redeemable convertible preferred stock is convertible into shares of common stock immediately upon (A) the date specified by written consent or written agreement of the holders of a majority of the outstanding shares of Series B’ redeemable convertible preferred stock and the Requisite Significant New Holders (as defined below) and (B) any firm commitment underwritten public offering approved by two new investors that have committed to the investment of an aggregate of $7,499,900 or more (each, a “Significant Investor”) in the Initial Closing and the Deferred Closing combined (such two Significant Investors, together, the “Requisite Significant New Holders”). Voting Rights The holders of redeemable convertible preferred stock shall have the right to one vote for each share of common stock into which such redeemable convertible preferred stock could then be converted. With respect to such vote, the holder shall have full voting rights and powers equal to the voting rights and powers of the holders of common stock, would have been entitled to notice of any stockholders’ meeting in accordance with the bylaws of the Company, and would have been entitled to vote, together with holders of common stock, with respect to any question upon which holders of common stock have the right to vote. Redemption and Balance Sheet Classification

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock Warrant Liability	3 Months Ended
	Mar. 31, 2021
Other Liabilities Disclosure [Abstract]
Redeemable Convertible Preferred Stock Warrant Liability	Redeemable Convertible Preferred Stock Warrant Liability On September 24, 2020, in connection with entering into the New Term Loan Agreement, the Company issued CRG Partners IV L.P. and its affiliates warrants to purchase 346,823 shares of Series B’ redeemable convertible preferred stock at an exercise price of $6.51339 per share, or the Series B’ Warrants, which was accounted as debt issuance costs. The Series B’ Warrants will terminate at the earlier of the ten The fair value of the Series B’ Warrants on the date of issuance of $0.6 million was recorded as a debt discount. The Series B’ Warrants had a fair value of $3.5 million and $0.4 million as of March 31, 2021 and December 31, 2020, respectively. The change in fair value of $(3.1) million during the three months ended March 31, 2021 was recorded as a component of other income (expense), net in the statements of operations and comprehensive loss. The redeemable convertible preferred stock warrant liability was valued using the following assumptions under the Black-Scholes option pricing model: March 31, December 31, 2021 2020 Stock price $14.50 $3.43 Expected term (in years) 9.5 9.7 Expected volatility 38.4% 39.0% Weighted average risk-free interest rate 1.68% 0.91% Dividend yield —% —% As of March 31, 2021, all Series B’ Warrants remained outstanding. Upon the closing of the IPO, the Series B’ Warrants net exercised to 213,941 shares of Series B’ convertible preferred stock and subsequently converted into common stock on a one-to-one basis.

Common Stock

Common Stock	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Common Stock	Common Stock The Company’s Certificate of Incorporation, as amended in August 2020, authorized the Company to issue 74,636,348 shares of $0.001 par value common stock. The holders of common stock are entitled to receive dividends whenever funds and assets are legally available and when declared by the Board of Directors, subject to the prior rights of holders of redeemable convertible preferred stock outstanding. As of March 31, 2021 and December 31, 2020, no dividends had been declared. As of March 31, 2021 and December 31, 2020, the Company had reserved common stock for future issuance as follows: March 31, December 31, 2021 2020 Conversion of Series A’ redeemable convertible preferred stock 635,048 635,048 Conversion of Series B’ redeemable convertible preferred stock 15,979,130 15,979,130 Outstanding options under the 2009 Plan 6 6 Outstanding options under the 2020 Plan 2,829,317 2,835,265 Options available for future grant under the 2020 Plan 668,299 818,889 Redeemable convertible preferred stock warrants issued and outstanding 346,823 346,823 Common stock warrants issued and outstanding 219 219 Total 20,458,842 20,615,380

Stock Option Plans

Stock Option Plans	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Stock Option Plans	Stock Option Plans A summary of stock option activity for the three months ended March 31, 2021 is set forth below: Options Outstanding Shares Available for Grant Number of Shares Weighted-Average Exercise Price Weighted Average Remaining Contractual Term (in Years) Balances as of January 1, 2021 818,889 2,835,265 $ 0.03 9.57 Options granted (188,361) 188,361 $ 1.04 Options exercised (156,538) $ 0.03 Options cancelled 37,771 (37,771) $ 0.03 Balances at March 31, 2021 668,299 2,829,317 $ 0.09 9.49 Vested and exercisable at March 31, 2021 450,358 $ 0.03 9.05 Vested and expected to vest at March 31, 2021 2,829,317 $ 0.03 9.49 Early Exercise of Stock Options The terms of the Company’s 2020 Stock Plan, or the 2020 Plan, permit the exercise of options granted under the 2020 Plan prior to vesting, subject to required approvals. The shares of common stock issued from the early exercise of unvested stock options are restricted and continue to vest over the original implied service period. The Company has the option to repurchase any unvested shares at the original purchase price upon any voluntary or involuntary termination. The shares purchased by the employees and non-employees pursuant to the early exercise of stock options are not deemed, for accounting purposes, to be outstanding until those shares vest. The cash received in exchange for exercised and unvested shares related to stock options granted is recorded as a liability for the early exercise of stock options in accrued liabilities on the accompanying balance sheet and will be transferred into common stock and additional paid-in capital as the shares vest. As of March 31, 2021 and December 31, 2020, there were 182,316 and 30,802 early exercised options subject to repurchase, respectively. The Company recognized stock-based compensation as follows: Three Months Ended March 31, 2021 2020 Cost of goods sold $ 10 $ 5 Research and development 37 100 Selling, general and administrative 155 196 Total stock-based compensation $ 202 $ 301 As of March 31, 2021, the total unrecognized stock-based compensation expense related to unvested stock options was $2.0 million, which will be amortized on a straight-line basis over a weighted average remaining period of 3.4 years.

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes The Company did not record a federal or state income tax provision or benefit for the three months ended March 31, 2021 and 2020 as it has incurred net losses since inception. In addition, the net deferred tax assets generated from net operating losses are fully offset by a valuation allowance as the Company believes it is not more likely than not that the benefit will be realized. The Company accounts for the uncertainty in income taxes by utilizing a comprehensive model for the recognition, measurement, presentation and disclosure in financial statements of any uncertain tax positions that

Net Loss per Share Attributable

Net Loss per Share Attributable to Common Stockholders	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common Stockholders The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except for share and per share amounts): Three Months Ended March 31, 2021 2020 Numerator: Net loss attributable to common stockholders $ (8,810) $ (6,741) Denominator: Weighted-average common stock outstanding used to compute basic and diluted net loss per share 269,178 202,341 Net loss per share attributable to common stockholders, basic and diluted $ (32.73) $ (33.32) The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding because such securities have an antidilutive impact due to the Company’s net loss, in common stock equivalent shares: As of March 31, 2021 2020 Redeemable convertible preferred shares 16,614,178 635,048 Options to purchase common stock 2,829,317 176,361 Unvested early exercised common stock options 182,316 83 Redeemable convertible preferred stock warrants 346,823 — 2019 and 2020 Convertible Notes* — — Total Shares 19,972,634 811,492 ______________ * As of March 31, 2020, the conversion of the 2019 and 2020 Convertible Notes into redeemable convertible preferred stock was dependent on the outstanding loan balance including accrued interest and the per share conversion price (see Note 6). Due to these factors, the number of shares of convertible preferred stock issuable upon conversion of the convertible notes was not determinable.

Related Parties

Related Parties	3 Months Ended
	Mar. 31, 2021
Related Party Transactions [Abstract]
Related Parties	Related Parties Covidien Group S.a.r.l., an indirect wholly-owned subsidiary of Medtronic, plc, became a holder of more than five percent of the Company’s capital stock in August 2020. Pursuant to the terms of a cross-license with Medtronic, the Company made royalty payments of approximately $0.1 million during both the three months ended March 31, 2021 and 2020. Also see Note 6 for additional related party transactions related to the 2019 and 2020 Convertible Notes.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	Subsequent EventsIn April 2021, the Board of Directors authorized the grant of options to purchase a total of 53,067 shares of common stock to employees at a weighted average exercise price of $16.00 per share.In April 2021, the Board of Directors authorized the grant of options to purchase a total of 130,188 shares of common stock to the non-employee directors at a weighted average exercise price of $17.00 per share.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation and Unaudited Interim Financial Information	Basis of Presentation The unaudited interim condensed financial statements have been prepared in conformity with generally accepted accounting principles in the United States, or GAAP, as defined by the Financial Accounting Standards Board, or the FASB. Unaudited Interim Financial Information The condensed balance sheet as of December 31, 2020 was derived from the Company’s audited financial statements, but does not include all disclosures required by GAAP. The accompanying unaudited condensed financial statements as of March 31, 2021 and for the three months ended March 31, 2021 and 2020, have been prepared by the Company, pursuant to the rules and regulations of the Securities and Exchange Commission, or the SEC, for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. However, the Company believes that the disclosures are adequate to make the information presented not misleading. Accordingly, these financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2020 and notes thereto, included in the Company’s final prospectus for the IPO filed with the SEC pursuant to Rule 424(b)(4) on April 23, 2021, or the final prospectus. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair statement of the Company’s condensed financial position as of March 31, 2021 and condensed results of operations and cash flows for the three months ended March 31, 2021 and 2020 have been made. The results of operations for the three months ended March 31, 2021 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2021.
Use of Estimates	Use of Estimates The preparation of unaudited interim condensed financial statements in conformity with GAAP requires the Company to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements. The Company uses significant judgment when making estimates related to the valuation of its common stock and related stock-based compensation, the valuation of deferred tax assets and related valuation allowances,
Fair Value of Financial Instruments	Fair Value of Financial Instruments Carrying amounts of certain of the Company’s financial instruments, including cash equivalents, accounts receivable, accounts payable and accrued liabilities, approximate fair value because of the short-term nature of these instruments. Short-term investments comprise available-for-sale debt securities, which are carried at fair value. The Company believes that its borrowings bear interest at the prevailing market rates for instruments with similar characteristics; accordingly, the carrying value of this instrument approximates its fair value. Derivative instruments and the redeemable convertible preferred stock warrant liability are carried at fair value based on unobservable market inputs. The Company determines the fair value of financial and non-financial assets and liabilities using the fair value hierarchy which establishes three levels of inputs that may be used to measure fair value (see Note 3). The Company measures certain financial assets and liabilities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or a liability. A three-tier fair value hierarchy is established as a basis for considering such assumptions and for inputs used in the valuation methodologies in measuring fair value: Level 1 Quoted prices in active markets for identical assets or liabilities. Level 2 Observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3 Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.
Concentration of Credit Risk, and Other Risks and Uncertainties	Concentration of Credit Risk, and Other Risks and Uncertainties Financial instruments that potentially subject the Company to credit risk consist of cash and cash equivalents, short-term investments and accounts receivable to the extent of the amounts recorded on the balance sheet. The Company’s cash is invested in one major financial institution in the United States. Deposits in this financial institution may exceed federally insured limits. The Company’s cash equivalents are invested in money market funds. The Company’s accounts receivable are due from a variety of health care organizations in the United States. For the three months ended March 31, 2021 and 2020, there were no customers that represented 10% or more of revenue. As of March 31, 2021 and December 31, 2020, no customer represented 10% or more of the Company’s accounts receivable. The Company is subject to certain risks, including that its devices may not be approved or cleared for marketing by governmental authorities or be successfully marketed for expanded indications. There can be no assurance that the Company’s products will achieve widespread adoption in the marketplace, nor can there be any assurance that existing devices or any future devices can be developed or manufactured at an acceptable cost and with appropriate performance characteristics. The Company is also subject to risks common to companies in the medical device industry, including, but not limited to, new technological innovations, dependence upon third-party payors to provide adequate coverage and reimbursement, dependence on key personnel, single-source suppliers and vendors in connection with the manufacture of its products, concentration of Level 4 CECs, obtaining, maintaining, protecting, enforcing, and defending intellectual property rights and proprietary technology, product liability claims, and compliance with government regulations. The Company’s medical devices require approvals or clearances from the U.S. Food and Drug Administration, or the FDA, or international regulatory agencies. In addition, in order to continue the Company’s operations, compliance with various federal and state laws is required. If approvals or clearances were withdrawn by the FDA for the Company’s current products or if such approvals or clearances were denied or delayed for future products, product updates, or expanded indications for use, it would have a material adverse impact on the Company.
Deferred Offering Costs	Deferred Offering CostsThe Company capitalizes, within other assets, certain legal, accounting and other third-party fees that are directly related to the Company’s in-process equity financings, including its initial public offering, until such financings are consummated. After consummation of the equity financing, these costs are recorded as a reduction of the proceeds received as a result of the offering. Should a planned equity financing be abandoned, terminated or significantly delayed, the deferred offering costs are immediately written off to operating expenses.
Net Loss per Share Attributable to Common Stockholders	Net Loss per Share Attributable to Common StockholdersBasic net loss per common share is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per share is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock and potentially dilutive securities outstanding for the period. For purposes of the diluted net loss per share calculation, redeemable convertible preferred stock, stock options, common stock subject to repurchase related to early exercise of stock options, and convertible notes are considered to be potentially dilutive securities. Basic and diluted net loss attributable to common stockholders per share is presented in conformity with the two-class method required for participating securities, as the redeemable convertible preferred stock is considered a participating security because it participates in dividends with common stock. The Company also considers the shares issued upon the early exercise of stock options subject to repurchase to be participating securities, because holders of such shares have non-forfeitable dividend rights in the event a dividend is paid on common stock. The holders of redeemable convertible preferred stock and the holders of the shares issued upon early exercise of stock options subject to repurchase do not have a contractual obligation to share in the Company’s losses. As such, the net loss was attributed entirely to common stockholders. Because the Company has reported a net loss for all periods presented, diluted net loss per common share is the same as basic net loss per common share for those periods.
Recent Accounting Pronouncements	Recent Accounting Pronouncements Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02 (Topic 842), Leases . ASU 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. This ASU provides a lessee with an option to not account for leases with a term of 12 month or less as leases in the scope of this ASU. This ASU will also require new qualitative and quantitative disclosures to help investors and other financial statement users better understand the amount, timing, and uncertainty of cash flows arising from leases. This ASU should be applied through a modified retrospective transition approach for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842): Targeted Improvements , which allows entities to elect an optional transition method where entities may continue to apply the existing lease guidance during the comparative periods and apply the new lease requirements through a cumulative effect adjustment in the period of adoption rather than in the earliest period presented. In June 2020, the FASB issued ASU 2020-05, Revenue from Contracts with Customers (Topic 606) and Leases (Topic 842): Effective Dates for Certain Entities, which delays the adoption dates for ASU 2016-02 for non-public entities to fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022. Early adoption is allowed. The Company expects to recognize a right-of-use asset and corresponding lease liability for its real estate operating leases upon adoption, expecting to use the modified retrospective approach for the adoption of this ASU. In June 2016, the FASB issued ASU 2016-13, Financial Instruments- Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments , which amends existing guidance on the impairment of financial assets and adds an impairment model that is based on expected losses rather than incurred losses and requires an entity to recognize as an allowance its estimate of expected credit losses for its financial assets. An entity will apply this guidance through a cumulative-effect adjustment to retained earnings upon adoption (a modified-retrospective approach) while a prospective transition approach is required for debt securities for which an other-than-temporary impairment had been recognized before the effective date. For public business entities that meet the definition of an SEC filer, excluding entities eligible to be smaller reporting companies as defined by the SEC, adoption is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. For SEC filers that are eligible to be smaller reporting companies and for all other entities, this ASU is effective for fiscal years beginning after December 15, 2022, and interim periods within those fiscal years. Early adoption is permitted. The Company is in the process of evaluating the impact of the adoption on its financial statements and related disclosures. In March 2020, the FASB issued ASU No. 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting . The amendments in ASU 2020-04 provide optional expedients and exceptions for applying generally accepted accounting principles to contracts, hedging relationships, and other transactions affected by reference rate reform if certain criteria are met. The amendments in this ASU are effective for all entities as of March 12, 2020 through December 31, 2022. An entity may elect to apply the amendments for contract modifications by Topic or Industry Subtopic as of any date from the beginning of an interim period that includes or is subsequent to March 12, 2020, or prospectively from the date that the financial statements are available to be issued. Once elected for a Topic or an Industry Subtopic, the amendments must be applied prospectively for all eligible contract modifications for that Topic or Industry Subtopic. The Company is currently evaluating the impact of the adoption of this ASU on the Company’s financial statements and related disclosures. In August 2020, the FASB issued ASU 2020-06, Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging-Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity . This ASU simplifies the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity’s own equity. Specifically the ASU removes: i) major separation models required under GAAP and ii) certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception, which will permit more equity contracts to qualify for the exception. For public business entities that meet the definition of an SEC filer, excluding entities eligible to be smaller reporting companies as defined by the SEC, this ASU is effective for interim and annual reporting periods beginning after December 15, 2021. For all other entities, the amendments are effective for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020, including interim periods within those fiscal years. The Company is currently evaluating the impact of the adoption of this ASU on the Company’s financial statements and related disclosures.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2021
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities, Measured at Fair Value	The following table summarizes the Company’s financial assets (cash equivalents, marketable securities and liabilities) at fair value as of March 31, 2021 (in thousands): Fair Value as of March 31, 2021 Basis for Fair Value Measurements (Level 1) (Level 2) (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 5,088 $ 5,088 $ — $ — Fixed income mutual funds, included in short-term investments 16,689 16,689 — — Total $ 21,777 $ 21,777 $ — $ — Liabilities: Redeemable convertible preferred stock warrant liability 3,491 — — 3,491 Total $ 3,491 $ — $ — $ 3,491 The following table summarizes the Company’s financial assets (cash equivalents, marketable securities and liabilities) at fair value as of December 31, 2020 (in thousands): Fair Value as of December 31, 2020 Basis for Fair Value Measurements (Level 1) (Level 2) (Level 3) Assets: Money market funds, included in cash and cash equivalents $ 5,062 $ 5,062 $ — $ — Fixed income mutual funds, included in short-term investments 11,689 11,689 — — Total $ 16,751 $ 16,751 $ — $ — Liabilities: Redeemable convertible preferred stock warrant liability 369 — — 369 Total $ 369 $ — $ — $ 369
Schedule of Debt Securities, Available-for-sale	The following is a summary of the Company’s available-for-sale debt securities (in thousands): March 31, December 31, 2021 2020 Cost basis $ 16,656 $ 11,656 Unrealized gain 33 33 Fair value $ 16,689 $ 11,689
Schedule of Fair Value Liabilities Measured at Level 3	The following table sets forth a summary of the changes in the fair value of the Company’s Level 3 financial instruments (in thousands): Redeemable Convertible Preferred Stock Warrant Liability Fair value as of January 1, 2021 $ 369 Change in fair value included in other income (expense), net 3,122 Fair value as of March 31, 2021 $ 3,491 Derivative Instrument Fair value as of January 1, 2020 $ 4,719 Recognition of derivative instrument related to 2020 Convertible Notes 1,669 Change in fair value included in other income (expense), net (1,705) Fair value as of March 31, 2020 $ 4,683

Balance Sheet Components (Table

Balance Sheet Components (Tables)	3 Months Ended
	Mar. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Inventory, Current	Inventories consist of the following (in thousands): March 31, December 31, 2021 2020 Raw materials $ 1,823 $ 1,721 Work-in-process 1,532 1,487 Finished goods 3,687 3,701 Total $ 7,042 $ 6,909
Property, Plant and Equipment	Property and equipment, net consists of the following (in thousands): March 31, December 31, 2021 2020 Machinery, equipment, furniture and fixtures $ 3,544 $ 3,544 Computer equipment and software 2,765 2,730 Leasehold improvements 2,402 2,402 8,711 8,676 Less: Accumulated depreciation (8,235) (8,161) Property and equipment, net $ 476 $ 515
Schedule of Accrued Liabilities	Accrued liabilities consist of the following (in thousands): March 31, December 31, 2021 2020 Payroll and related expenses $ 3,708 $ 4,565 Inventory-raw materials 471 636 Professional fees 641 279 Deferred rent, current 585 666 Clinical trials 36 107 Other 293 350 $ 5,734 $ 6,603

Commitments and Contingencies (

Commitments and Contingencies (Tables)	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
Schedule of Minimum Annual Lease Commitments	The Company’s future payments under the non-cancellable operating lease (in thousands) are as follows: March 31, 2021 (remaining nine months) $ 2,632 2022 3,172 2023 3,267 2024 1,666 Total $ 10,737

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Maturities of Long-term Debt	As of March 31, 2021, future minimum payments for the New Term Loan and PPP Loan are as follows (in thousands): New Term Loan PPP Loan 2021 (remaining nine months) $ 4,774 $ 2,060 2022 6,337 2,060 2023 12,587 — 2024 29,364 — 2025 24,931 — Total 77,993 4,120 Less: Unamortized debt discount and issuance cost (1,360) — Less: Unaccreted backend fee (4,577) — Less: Interest (22,993) (32) Total future minimum payments $ 49,063 $ 4,088

Redeemable Convertible Prefer_3

Redeemable Convertible Preferred Stock (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Schedule of Temporary Equity	As of March 31, 2021 and December 31, 2020, the redeemable convertible preferred stock comprises (in thousands, except per share and share amounts): Number of Shares Authorized Number of Shares Issued and Outstanding Carrying Amount Liquidation Value Original Issue Price Series A’ 1,651,154 635,048 $ 73,340 $ 36,945 $ 58.1750 Series B’ 59,106,232 15,979,130 $ 68,082 $ 190,810 $ 4.3423 60,757,386 16,614,178 $ 141,422 $ 227,755

Redeemable Convertible Prefer_4

Redeemable Convertible Preferred Stock Warrant Liability (Tables)	3 Months Ended
	Mar. 31, 2021
Other Liabilities Disclosure [Abstract]
Schedule of Measurement Inputs	The redeemable convertible preferred stock warrant liability was valued using the following assumptions under the Black-Scholes option pricing model: March 31, December 31, 2021 2020 Stock price $14.50 $3.43 Expected term (in years) 9.5 9.7 Expected volatility 38.4% 39.0% Weighted average risk-free interest rate 1.68% 0.91% Dividend yield —% —%

Common Stock (Tables)

Common Stock (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Schedule of Stock by Class	As of March 31, 2021 and December 31, 2020, the Company had reserved common stock for future issuance as follows: March 31, December 31, 2021 2020 Conversion of Series A’ redeemable convertible preferred stock 635,048 635,048 Conversion of Series B’ redeemable convertible preferred stock 15,979,130 15,979,130 Outstanding options under the 2009 Plan 6 6 Outstanding options under the 2020 Plan 2,829,317 2,835,265 Options available for future grant under the 2020 Plan 668,299 818,889 Redeemable convertible preferred stock warrants issued and outstanding 346,823 346,823 Common stock warrants issued and outstanding 219 219 Total 20,458,842 20,615,380

Stock Option Plans (Tables)

Stock Option Plans (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Summary of Stock Option Activity	A summary of stock option activity for the three months ended March 31, 2021 is set forth below: Options Outstanding Shares Available for Grant Number of Shares Weighted-Average Exercise Price Weighted Average Remaining Contractual Term (in Years) Balances as of January 1, 2021 818,889 2,835,265 $ 0.03 9.57 Options granted (188,361) 188,361 $ 1.04 Options exercised (156,538) $ 0.03 Options cancelled 37,771 (37,771) $ 0.03 Balances at March 31, 2021 668,299 2,829,317 $ 0.09 9.49 Vested and exercisable at March 31, 2021 450,358 $ 0.03 9.05 Vested and expected to vest at March 31, 2021 2,829,317 $ 0.03 9.49
Share-based Payment Arrangement, Expensed and Capitalized, Amount	The Company recognized stock-based compensation as follows: Three Months Ended March 31, 2021 2020 Cost of goods sold $ 10 $ 5 Research and development 37 100 Selling, general and administrative 155 196 Total stock-based compensation $ 202 $ 301

Net Loss per Share Attributab_2

Net Loss per Share Attributable to Common Stockholders (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders (in thousands, except for share and per share amounts): Three Months Ended March 31, 2021 2020 Numerator: Net loss attributable to common stockholders $ (8,810) $ (6,741) Denominator: Weighted-average common stock outstanding used to compute basic and diluted net loss per share 269,178 202,341 Net loss per share attributable to common stockholders, basic and diluted $ (32.73) $ (33.32)
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following potentially dilutive securities outstanding have been excluded from the computation of diluted weighted average shares outstanding because such securities have an antidilutive impact due to the Company’s net loss, in common stock equivalent shares: As of March 31, 2021 2020 Redeemable convertible preferred shares 16,614,178 635,048 Options to purchase common stock 2,829,317 176,361 Unvested early exercised common stock options 182,316 83 Redeemable convertible preferred stock warrants 346,823 — 2019 and 2020 Convertible Notes* — — Total Shares 19,972,634 811,492 ______________ * As of March 31, 2020, the conversion of the 2019 and 2020 Convertible Notes into redeemable convertible preferred stock was dependent on the outstanding loan balance including accrued interest and the per share conversion price (see Note 6). Due to these factors, the number of shares of convertible preferred stock issuable upon conversion of the convertible notes was not determinable.

The Company (Details)

The Company (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 26, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Aug. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Common stock authorized (in shares)		74,636,348		74,636,348	74,636,348
Common stock par value (in dollars per share)		$ 0.001		$ 0.001	$ 0.001
Net loss		$ 8,810	$ 6,741
Net cash used in operating activities		5,936	$ 6,548
Accumulated deficit		396,501		$ 387,691
Cash, cash equivalents, and short-term investments		$ 30,500
Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Common stock authorized (in shares)	200,000,000
Common stock par value (in dollars per share)	$ 0.001
Shares authorized (in shares)	10,000,000
Preferred stock, par value (in dollars per share)	$ 0.001
Minimum annual net revenue	$ 43,000
Minimum cash and cash equivalents required after completion of IPO	$ 5,000
IPO | Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Number of shares issued in transaction (in shares)	6,900,000
Sale of stock (in dollars per share)	$ 17
Proceeds from issuance initial public offering	$ 117,300
Consideration received on transaction	$ 105,200
Over-Allotment Option | Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Number of shares issued in transaction (in shares)	900,000
Redeemable Convertible Preferred Stock Converted Into Common Stock | Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Conversion of stock, shares issued (in shares)	16,614,178
Redeemable Convertible Preferred Stock Converted Into Warrants To Purchase Series B' Convertible Preferred Stock | Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Conversion of stock, shares issued (in shares)	346,823
Redeemable Convertible Preferred Stock Converted Into Warrants Exercised To Series B' Convertible Preferred Stock | Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Conversion of stock, shares issued (in shares)	213,941
Redeemable Convertible Preferred Stock Converted Into Warrants To Purchase Common Stock | Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Conversion of stock, shares issued (in shares)	219
Redeemable Convertible Preferred Stock Converted Into Warrants Exercised To Common Stock | Subsequent Event
Finite-Lived Intangible Assets [Line Items]
Conversion of stock, shares issued (in shares)	185

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Details) $ in Thousands	Apr. 09, 2021	Aug. 18, 2020	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reverse stock split, conversion ratio		0.0100
Deferred offering costs			$ 2,371	$ 484
Subsequent Event
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reverse stock split, conversion ratio	0.3846

Fair Value Measurements - Asset

Fair Value Measurements - Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Assets, Fair Value Disclosure [Abstract]
Money market funds, included in cash and cash equivalents	$ 5,088	$ 5,062
Fixed income mutual funds, included in short-term investments	16,689	11,689
Total	21,777	16,751
Liabilities, Fair Value Disclosure [Abstract]
Redeemable convertible preferred stock warrant liability	3,491	369
Total	3,491	369
Fair Value, Inputs, Level 1
Assets, Fair Value Disclosure [Abstract]
Money market funds, included in cash and cash equivalents	5,088	5,062
Fixed income mutual funds, included in short-term investments	16,689	11,689
Total	21,777	16,751
Liabilities, Fair Value Disclosure [Abstract]
Redeemable convertible preferred stock warrant liability	0	0
Total	0	0
Fair Value, Inputs, Level 2
Assets, Fair Value Disclosure [Abstract]
Money market funds, included in cash and cash equivalents	0	0
Fixed income mutual funds, included in short-term investments	0	0
Total	0	0
Liabilities, Fair Value Disclosure [Abstract]
Redeemable convertible preferred stock warrant liability	0	0
Total	0	0
Fair Value, Inputs, Level 3
Assets, Fair Value Disclosure [Abstract]
Money market funds, included in cash and cash equivalents	0	0
Fixed income mutual funds, included in short-term investments	0	0
Total	0	0
Liabilities, Fair Value Disclosure [Abstract]
Redeemable convertible preferred stock warrant liability	3,491	369
Total	$ 3,491	$ 369

Fair Value Measurements - Avail

Fair Value Measurements - Available for Sale Debt Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Cost basis	$ 16,656	$ 11,656
Unrealized gain	33	33
Fair value	$ 16,689	$ 11,689

Fair Value Measurements - Chang

Fair Value Measurements - Changes in Fair Value of Level 3 Financial Instruments (Details) - Fair Value, Inputs, Level 3 - Derivative Instrument - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	$ 369	$ 4,719
Recognition of derivative instrument related to 2020 Convertible Notes		1,669
Change in fair value	3,122	(1,705)
Balance at end of period	$ 3,491	$ 4,683

Balance Sheet Components - Inve

Balance Sheet Components - Inventory (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 1,823	$ 1,721
Work-in-process	1,532	1,487
Finished goods	3,687	3,701
Inventory	$ 7,042	$ 6,909

Balance Sheet Components - Prop

Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 8,711		$ 8,676
Less: Accumulated depreciation	(8,235)		(8,161)
Property and equipment, net	476		515
Depreciation	74	$ 82
Machinery, equipment, furniture and fixtures
Property, Plant and Equipment [Line Items]
Property and equipment, net	3,544		3,544
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property and equipment, net	2,765		2,730
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property and equipment, net	$ 2,402		$ 2,402

Balance Sheet Components - Accr

Balance Sheet Components - Accrued Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Payroll and related expenses	$ 3,708	$ 4,565
Inventory-raw materials	471	636
Professional fees	641	279
Deferred rent, current	585	666	$ 300
Clinical trials	36	107
Other	293	350
Accrued Liabilities	$ 5,734	$ 6,603

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended	2 Months Ended	3 Months Ended
	May 31, 2018	Jun. 30, 2020	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Oct. 01, 2020	May 31, 2019	Aug. 31, 2011
Loss Contingencies [Line Items]
Renewal term	5 years
Percent rental payment deferred		50.00%
Deferred rent, current		$ 300	$ 585		$ 666
Deferred rent, interest rate, annual rate						8.00%
Operating leases, rent expense			700	$ 700
Deferred rent credit			$ 1,800		$ 2,000
Lease Facility
Loss Contingencies [Line Items]
Face amount							$ 700	$ 900
Minimum
Loss Contingencies [Line Items]
Annual rental payments	$ 2,900
Maximum
Loss Contingencies [Line Items]
Annual rental payments	$ 3,300

Commitments and Contingencies_2

Commitments and Contingencies - Operating Lease Maturity (Details) $ in Thousands	Mar. 31, 2021USD ($)
Commitments and Contingencies Disclosure [Abstract]
2021 (remaining nine months)	$ 2,632
2022	3,172
2023	3,267
2024	1,666
Total	$ 10,737

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($)	Apr. 26, 2021	Mar. 31, 2020	Apr. 30, 2021	Sep. 30, 2020	Mar. 31, 2020	Jan. 31, 2020	Sep. 30, 2019	Mar. 31, 2019	Nov. 30, 2014	Mar. 31, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Apr. 30, 2021	Mar. 31, 2020	Sep. 30, 2016	Dec. 31, 2020	Sep. 24, 2020	Jul. 01, 2020	Apr. 30, 2020	Dec. 31, 2019	Oct. 31, 2019	Sep. 30, 2017
Debt Instrument [Line Items]
Interest rate				12.50%							12.50%
PIK interest incurred but not paid on term loan										$ 0		$ 1,350,000
Redeemable convertible preferred stock warrant liability										3,491,000							$ 369,000
Effective percentage				16.08%							16.08%
Proceeds from convertible debt										0		12,514,000
Proceeds from related party debt										0		11,867,000
Interest expense, related party										0		$ 461,000
Series B Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion price (in dollars per share)		$ 4.3423			$ 4.3423							$ 4.3423			$ 4.3423
Convertible Debt
Debt Instrument [Line Items]
Interest rate		8.00%			8.00%							8.00%			8.00%
Interest payment												$ 900,000
Interest expense												1,400,000
Equity financing proceed threshold for conversion		$ 18,000,000			$ 18,000,000							18,000,000			$ 18,000,000
Threshold percentage of stock price trigger															85.00%
Amortization of debt discount												500,000
Proceeds from related party debt												10,300,000
Interest expense, related party												$ 500,000
Convertible Debt | Series A Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion price (in dollars per share)		$ 116.35			$ 116.35							$ 116.35			$ 116.35
Repayment premium percent		100.00%			100.00%							100.00%			100.00%
Convertible Debt | Series B Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Conversion discount		15.00%			15.00%							15.00%			15.00%
Convertible debt outstanding		$ 33,900,000			$ 33,900,000							$ 33,900,000			$ 33,900,000
Interest payable		$ 2,500,000			$ 2,500,000							$ 2,500,000			$ 2,500,000
Converted instrument, shares issued (in shares)															8,379,410
Share issuance price percentage		100.00%			100.00%							100.00%			100.00%
Gain (loss) on extinguishment of debt											$ 4,100,000
Maximum | Convertible Debt
Debt Instrument [Line Items]
Effective percentage																	12.20%
Minimum | Convertible Debt
Debt Instrument [Line Items]
Effective percentage																	10.80%
Redeemable Convertible Preferred Stock Converted Into Warrants To Purchase Common Stock | Subsequent Event
Debt Instrument [Line Items]
Conversion of stock, shares issued (in shares)	219
Redeemable Convertible Preferred Stock Converted Into Warrants Exercised To Common Stock | Subsequent Event
Debt Instrument [Line Items]
Conversion of stock, shares issued (in shares)	185
2014 Term Loan
Debt Instrument [Line Items]
Face amount									$ 40,000,000												$ 40,000,000
Interest rate									12.50%														8.00%
Interest rate, paid-in-kind																							4.50%
PIK interest incurred but not paid on term loan		$ 1,400,000														$ 2,700,000
Redemption fee, percent									5.00%
Payments of debt issuance costs									$ 800,000
Effective percentage						14.70%	15.00%						15.00%						14.20%			14.70%
Interest payment		$ 1,400,000		$ 1,300,000
Repayments of debt				47,600,000
Repurchased face amount				44,100,000							44,100,000
Payment for debt extinguishment				2,200,000
2014 Term Loan | Series I Preferred Stock
Debt Instrument [Line Items]
Number of securities called by warrants or rights (in shares)									219
Exercise price of warrant (in dollars per share)									$ 1,866.80
Redeemable convertible preferred stock warrant liability									$ 300,000
2014 Term Loan | Common stock warrants issued and outstanding
Debt Instrument [Line Items]
Number of securities called by warrants or rights (in shares)									219
Exercise price of warrant (in dollars per share)									$ 2.60
2020 Term Loans
Debt Instrument [Line Items]
Face amount				$ 50,000,000							$ 50,000,000
Redemption fee, percent				10.00%							10.00%
Unused borrowing capacity				$ 10,000,000							$ 10,000,000
Amortization of debt issuance costs										100,000
Interest expense										1,800,000
2020 Term Loans | Maximum
Debt Instrument [Line Items]
Face amount				60,000,000							60,000,000
2020 Term Loans | Series B Redeemable Convertible Preferred Stock
Debt Instrument [Line Items]
Exercise price of warrant (in dollars per share)																		$ 6.51339
Redeemable convertible preferred stock warrant liability										$ 3,500,000							$ 400,000	$ 600,000
Backend fee				$ 1,000,000							$ 1,000,000
Warrants outstanding (in shares)																		346,823
Paycheck Protection Program
Debt Instrument [Line Items]
Face amount																				$ 4,000,000
Interest rate																				1.00%
Paycheck Protection Program | Subsequent Event
Debt Instrument [Line Items]
Interest payment														$ 100,000
Repurchased face amount			$ 4,000,000											$ 4,000,000
Extinguishment of debt			$ 4,100,000
2019 Convertible Notes | Convertible Debt
Debt Instrument [Line Items]
Proceeds from convertible debt													$ 21,300,000
Amortization of debt discount							$ 1,900,000	$ 4,100,000
2020 Convertible Notes | Convertible Debt
Debt Instrument [Line Items]
Proceeds from convertible debt					$ 5,400,000	$ 7,100,000
Amortization of debt discount					$ 700,000	$ 1,000,000

Debt - Maturities of Debt (Deta

Debt - Maturities of Debt (Details) $ in Thousands	Mar. 31, 2021USD ($)
New Term Loan
Debt Instrument [Line Items]
Remainder of 2021	$ 4,774
2022	6,337
2023	12,587
2024	29,364
2025	24,931
Total	77,993
Less: Unamortized debt discount and issuance cost	(1,360)
Less: Unaccreted backend fee	(4,577)
Less: Interest	(22,993)
Total future minimum payments	49,063
PPP Loan
Debt Instrument [Line Items]
Remainder of 2021	2,060
2022	2,060
2023	0
2024	0
2025	0
Total	4,120
Less: Unamortized debt discount and issuance cost	0
Less: Unaccreted backend fee	0
Less: Interest	(32)
Total future minimum payments	$ 4,088

Redeemable Convertible Prefer_5

Redeemable Convertible Preferred Stock - Additional Information (Details)	Apr. 26, 2021shares	Aug. 31, 2020USD ($)series$ / sharesshares	Mar. 31, 2021USD ($)vote$ / shares	Mar. 31, 2020USD ($)shares	Dec. 31, 2020$ / shares
Class of Stock [Line Items]
Redeemable convertible preferred stock, par value (in dollars per share)			$ 0.001		$ 0.001
Subsequent Event | Redeemable Convertible Preferred Stock Converted Into Common Stock
Class of Stock [Line Items]
Conversion of stock, shares issued (in shares) | shares	16,614,178
Series B Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Number of series of preferred stock | series		2
New issues (in shares) | shares		7,599,720
Redemption price (in dollars per share)		$ 4.3423
Proceeds from issuance of redeemable convertible preferred stock | $		$ 33,000,000
Dividends per annum (in dollars per share)			$ 0.3474
Cash balance trigger | $			$ 4,000,000
Liquidation multiplier, before deferred closing date			2.75
Liquidation multiplier, between initial closing and December 31, 2021			2.75
Liquidation multiplier, all other scenarios			3
Aggregate investment conversion threshold | $			$ 7,499,900
Redeemable convertible preferred stock, par value (in dollars per share)			$ 4.3423		4.3423
Series B Redeemable Convertible Preferred Stock | Convertible Debt
Class of Stock [Line Items]
Convertible debt outstanding | $				$ 33,900,000
Interest payable | $				$ 2,500,000
Converted instrument, shares issued (in shares) | shares				8,379,410
Series A Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Dividends per annum (in dollars per share)			4.6540
Redeemable convertible preferred stock, par value (in dollars per share)			$ 58.1750		$ 58.1750
Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Number of votes per share | vote			1

Redeemable Convertible Prefer_6

Redeemable Convertible Preferred Stock - Schedule of Stock (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized (in shares)	60,757,386	60,757,386
Redeemable convertible preferred stock, shares issued (in shares)	16,614,178	16,614,178
Redeemable convertible preferred stock, shares outstanding (in shares)	16,614,178	16,614,178	635,048	635,048
Carrying Amount	$ 141,422	$ 141,422	$ 73,568	$ 73,568
Liquidation Value	$ 227,755	$ 227,755
Original Issue Price (in dollars per share)	$ 0.001	$ 0.001
Series A Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized (in shares)	1,651,154	1,651,154
Redeemable convertible preferred stock, shares issued (in shares)	635,048	635,048
Redeemable convertible preferred stock, shares outstanding (in shares)	635,048	635,048
Carrying Amount	$ 73,340	$ 73,340
Liquidation Value	$ 36,945	$ 36,945
Original Issue Price (in dollars per share)	$ 58.1750	$ 58.1750
Series B Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Redeemable convertible preferred stock, shares authorized (in shares)	59,106,232	59,106,232
Redeemable convertible preferred stock, shares issued (in shares)	15,979,130	15,979,130
Redeemable convertible preferred stock, shares outstanding (in shares)	15,979,130	15,979,130
Carrying Amount	$ 68,082	$ 68,082
Liquidation Value	$ 190,810	$ 190,810
Original Issue Price (in dollars per share)	$ 4.3423	$ 4.3423

Redeemable Convertible Prefer_7

Redeemable Convertible Preferred Stock Warrant Liability - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 26, 2021	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Sep. 24, 2020
Class of Warrant or Right [Line Items]
Redeemable convertible preferred stock warrant liability		$ 3,491		$ 369
Change in fair value of redeemable convertible preferred stock warrant liability		(3,122)	$ 0
Redeemable Convertible Preferred Stock Converted Into Warrants Exercised To Series B' Convertible Preferred Stock | Subsequent Event
Class of Warrant or Right [Line Items]
Conversion of stock, shares issued (in shares)	213,941
Series B Redeemable Convertible Preferred Stock | 2020 Term Loans
Class of Warrant or Right [Line Items]
Warrants outstanding (in shares)					346,823
Exercise price of warrant (in dollars per share)					$ 6.51339
Warrants term					10 years
Redeemable convertible preferred stock warrant liability		3,500		$ 400	$ 600
Change in fair value of redeemable convertible preferred stock warrant liability		$ (3,100)

Redeemable Convertible Prefer_8

Redeemable Convertible Preferred Stock Warrant Liability - Schedule of Assumptions (Details)	Mar. 31, 2021$ / shares	Dec. 31, 2020$ / shares
Stock price
Class of Warrant or Right [Line Items]
Measurement input	14.50	3.43
Expected term
Class of Warrant or Right [Line Items]
Measurement input	9.5	9.7
Expected volatility
Class of Warrant or Right [Line Items]
Measurement input	384	390
Weighted average risk-free interest rate
Class of Warrant or Right [Line Items]
Measurement input	0.0168	0.0091
Dividend yield
Class of Warrant or Right [Line Items]
Measurement input	0	0

Common Stock (Details)

Common Stock (Details) - $ / shares	Mar. 31, 2021	Dec. 31, 2020	Aug. 31, 2020
Class of Stock [Line Items]
Common stock authorized (in shares)	74,636,348	74,636,348	74,636,348
Common stock par value (in dollars per share)	$ 0.001	$ 0.001	$ 0.001
Common stock reserved for future issuance (in shares)	20,458,842	20,615,380
Series A Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	635,048	635,048
Series B Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	15,979,130	15,979,130
Outstanding options under the 2009 Plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	6	6
Outstanding options under the 2020 Plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	2,829,317	2,835,265
Options available for future grant under the 2020 Plan
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	668,299	818,889
Redeemable convertible preferred stock warrants issued and outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	346,823	346,823
Common stock warrants issued and outstanding
Class of Stock [Line Items]
Common stock reserved for future issuance (in shares)	219	219

Stock Option Plans - Summary of

Stock Option Plans - Summary of Stock Option Activity (Details) - $ / shares	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Shares Available for Grant (in shares)	668,299	818,889
Number of Shares
Beginning balance (in shares)	2,835,265
Options granted (in shares)	188,361
Options exercised (in shares)	(156,538)
Options cancelled (in shares)	(37,771)
Ending balance (in shares)	2,829,317	2,835,265
Vested and exercisable (in shares)	450,358
Vested and expected to vest (in shares)	2,829,317
Weighted-Average Exercise Price
Beginning balance (in dollars per share)	$ 0.03
Options granted (in dollar per share)	1.04
Options exercised (in dollar per share)	0.03
Options cancelled (in dollar per share)	0.03
Ending balance (in dollars per share)	0.09	$ 0.03
Vested and exercisable (in dollars per share)	0.03
Vested and expected to vest (in dollars per share)	$ 0.03
Weighted Average Remaining Contractual Term (in Years)
Balance	9 years 5 months 26 days	9 years 6 months 25 days
Exercisable	9 years 18 days
Vested and expected to vest	9 years 5 months 26 days

Stock Option Plans - Additional

Stock Option Plans - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Options, subject to repurchase (in shares)	182,316	30,802
Cost not yet recognized	$ 2
Period for recognition	3 years 4 months 24 days

Stock Option Plans - Summary _2

Stock Option Plans - Summary of Recognized Stock-based Compensation (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 202	$ 301
Cost of goods sold
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	10	5
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	37	100
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation	$ 155	$ 196

Income Taxes (Details)

Income Taxes (Details) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income tax expense	$ 0	$ 0

Net Loss per Share Attributab_3

Net Loss per Share Attributable to Common Stockholders - Computation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Numerator:
Net loss attributable to common stockholders	$ (8,810)	$ (6,741)
Denominator:
Weighted-average common stock outstanding used to compute basic net loss per share (in shares)	269,178	202,341
Weighted-average common stock outstanding used to compute diluted net loss per share (in shares)	269,178	202,341
Net loss per share attributable to common stockholders, diluted (in dollars per share)	$ (32.73)	$ (33.32)
Net loss per share attributable to common stockholders, basic (in dollars per share)	$ (32.73)	$ (33.32)

Net Loss per Share Attributab_4

Net Loss per Share Attributable to Common Stockholders - Schedule of Potentially Dilutive Securities Outstanding (Details) - shares	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares (in shares)	19,972,634	811,492
Redeemable convertible preferred shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares (in shares)	16,614,178	635,048
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares (in shares)	2,829,317	176,361
Unvested early exercised common stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares (in shares)	182,316	83
Redeemable convertible preferred stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares (in shares)	346,823	0
2019 and 2020 Convertible Notes
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total shares (in shares)	0	0

Related Parties (Details)

Related Parties (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Affiliated Entity
Related Party Transaction [Line Items]
Payments for royalties	$ 0.1	$ 0.1

Subsequent Events (Details)

Subsequent Events (Details) - $ / shares	1 Months Ended	3 Months Ended
	Apr. 30, 2021	Mar. 31, 2021
Subsequent Event [Line Items]
Options granted (in shares)		188,361
Subsequent Event | Share-based Payment Arrangement, Employee
Subsequent Event [Line Items]
Options granted (in shares)	53,067
Options, grant date fair value (in dollars per share)	$ 16
Subsequent Event | Share-based Payment Arrangement, Nonemployee
Subsequent Event [Line Items]
Options granted (in shares)	130,188
Options, grant date fair value (in dollars per share)	$ 17