Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (24,881)	$ (11,509)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	208	245
Noncash lease expense relating to operating lease right-of-use assets	317
Noncash interest expense related to bank loans	0	114
Inventory write-downs, net of scrapped inventory	267	0
Change in fair value of embedded derivative liability and warrant liabilities	32	(17)
Stock-based compensation	5,340	1,610
Amortization of debt issuance costs	0	283
Amortization of premiums on marketable securities, net of change in accrued interest	594	0
Changes in operating assets and liabilities:
Accounts receivable, net	3,930	(205)
Inventories, net	(436)	(235)
Prepaid and other current assets	510	332
Other noncurrent assets	400	(2,785)
Accounts payable	(567)	2,494
Accrued expenses and other current liabilities	(645)	873
Operating lease liabilities	(325)
Deferred rent		(133)
Contract liabilities	(767)	119
Net cash used in operating activities	(16,023)	(8,814)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(774)	(121)
Proceeds from redemption of marketable securities	15,500	0
Net cash provided by (used in) operating activities	14,726	(121)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from exercise of stock options	222	85
Proceeds from the issuance of convertible notes	0	8,045
Principal payments - bank loan	0	(333)
Taxes paid related to the net share settlement of equity awards	(1,931)	0
Net cash provided by (used in) financing activities	(1,709)	7,797
NET DECREASE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH	(3,006)	(1,138)
CASH, CASH EQUIVALENTS AND RESTRICTED CASH—Beginning of period	16,333	16,497
CASH, CASH EQUIVALENTS AND RESTRICTED CASH—Ending	13,327	15,359
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for interest	0	44
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property and equipment included in accounts payable and accrued liabilities	260	35
Taxes related to net settlement of restricted stock units included in accrued liabilities	53	$ 0
Operating lease right-of-use assets obtained in exchange for lease obligations upon adoption of ASC 842	$ 16,284