CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities
Net loss	$ (56,572)	$ (43,697)
Adjustments to reconcile net loss to net cash used in operating activities
Stock-based compensation	16,866	11,927
Depreciation and amortization	2,086	1,130
Bad debt expense	14	234
Accretion of discount on marketable securities	1,294	115
Realized gain on marketable securities	0	(46)
Amortization of debt issuance costs	288	292
Loss on extinguishment of debt	1,848	1,534
Loss on sale and disposal of property and equipment	399	376
Changes in operating assets and liabilities
Accounts receivable	(569)	(2,186)
Inventory	(5,784)	(274)
Prepaid expenses and other assets	(594)	(136)
Accounts payable	(532)	835
Accrued liabilities and other	1,723	(766)
Net cash used in operating activities	(39,533)	(30,662)
Cash flows from investing activities
Maturities of marketable securities	159,990	104,716
Sales of marketable securities	0	14,095
Purchases of marketable securities	(102,021)	(179,166)
Purchases of property and equipment	(6,389)	(2,561)
Net cash (used in) provided by investing activities	51,580	(62,916)
Cash flows from financing activities
Proceeds from follow-on public offering, net of underwriting discounts, commissions and offering costs	0	134,616
Proceeds from debt financing	35,000	45,297
Repayments of debt financing	(41,000)	(45,297)
Payments of debt issuance costs	(111)	(750)
Payments of prepayment penalty and lender fees	(508)	(843)
Proceeds from the exercise of common stock options	2,565	1,463
Proceeds from issuance of common stock under employee stock purchase plan	2,343	1,915
Net cash (used in) provided by financing activities	(1,711)	136,401
Effect of exchange rate changes on cash and cash equivalents	(498)	323
Net increase in cash and cash equivalents	9,838	43,146
Cash and cash equivalents at
Beginning of year	53,581	10,435
End of year	63,419	53,581
Supplemental disclosure of cash flow information
Cash paid for interest	3,230	4,276
Supplemental disclosure of non-cash information
Vesting of early exercised stock options	27	71
Unpaid purchases of property and equipment	$ 509	$ 26