Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating Activities:
Net loss	$ (17,596)	$ (6,805)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,016	958
Amortization of right-of-use lease assets	19	8
Amortization of debt issuance costs and premium	130	114
Gain on expiration of warrant	0	(5,018)
Amortization of discount on short-term investments	(47)	(10)
Stock-based compensation	2,649	1,239
Provision for excess and obsolete inventory	73	(7)
Change in operating assets and liabilities:
Accounts receivable	(764)	600
Inventories	(530)	(1,465)
Prepaid and other assets	814	(89)
Accounts payable	701	721
Accrued expenses and other liabilities	(1,450)	(498)
Net cash used in operating activities	(14,985)	(10,252)
Investing Activities:
Purchases of property and equipment	(370)	(498)
Maturity of short-term investments	90,000	20,000
Purchases of short-term investments	(74,771)	(4,999)
Net cash provided by investing activities	14,859	14,503
Financing Activities:
Proceeds from term loan		5,000
Payments of debt issuance costs		(40)
Payments for employee taxes related to stock compensation	(362)
Principal payments on finance lease liabilities	(44)	(9)
Change in notes receivables for redeemable common stock issued		(14)
Proceeds from exercise of stock options	308	1,207
Net cash (used in) provided by financing activities	(98)	6,144
Effect of foreign exchange rate on cash, cash equivalents and restricted cash	(5)	(4)
Net (decrease) increase in cash, cash equivalents and restricted cash	(229)	10,391
Cash, cash equivalents and restricted cash - beginning of period	25,172	14,455
Cash, cash equivalents and restricted cash - end of period	24,943	24,846
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	499	294
Cash paid for income taxes		11
Cash paid for interest on financing leases	3	2
Cash paid for interest on term loan	925	582
Right-of-use assets obtained in exchange for lease obligations:
Operating lease	87
Finance Lease	192
Lease obligations recorded for right-of-use assets:
Operating lease	87
Finance Lease	166
Acquisition of property and equipment included in accounts payable and accrued expenses and other current liabilities	197	60
Payment-in-kind interest income added to principal of notes receivable		13
Reclassification of 4,093,995 shares of redeemable common stock to 4,093,995 shares of common stock		87,702
Reclassification of redeemable common stock options to common stock options		$ 47,370