CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (11,475)	$ (6,660)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	704	772
Amortization of right-of-use assets	427	500
Amortization of intangible assets	69	47
Amortization of debt discount and deferred financing fees	220	112
Provision for bad debt	267	(26)
Provision for inventory write-down	459	783
Change in fair value of derivatives	(252)	22
Investment losses	96	15
Stock-based compensation	2,678	2,694
Change in operating assets and liabilities:
Accounts receivable	(624)	(2,181)
Inventory	(1,166)	(1,642)
Prepaid expenses and other	(1,030)	(313)
Accounts payable and accrued expenses	(1,104)	(5,061)
Operating lease obligations	(320)	119
Contract and other liabilities	0	(1)
Net cash used in operating activities	(11,051)	(10,820)
Cash flows from investing activities:
Purchase of property and equipment	(5,037)	(3,095)
Purchase of investments	(6,024)	(15,279)
Proceeds from sale of investments	4,400	19,400
Cash payments for intangible assets	(580)	(156)
Net cash (used in) provided by investing activities	(7,241)	870
Cash flows from financing activities:
Cash paid for debt portion of finance leases	(2)	(4)
Proceeds from exercise of stock options and ESPP stock purchases	97	521
Net cash provided by financing activities	95	517
Net decrease in cash, cash equivalents, and restricted cash	(18,197)	(9,433)
Cash, cash equivalents, and restricted cash, beginning of period	39,007	55,609
Cash, cash equivalents, and restricted cash, end of period	20,810	46,176
Supplemental disclosures of cash flow activity:
Cash paid for interest, net of capitalized interest	0	312
Supplemental disclosure of non-cash investing and financing activities:
Acquisition of fixed assets in accounts payable and accrued expenses	1,119	4,836
Obtaining a right-of-use asset in exchange for a lease liability	641	321
Acquisition of intangible assets in accounts payable and accrued expenses	$ 239	$ 166