Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cash flow from operating activities:
Net loss	$ (1,643)	$ (11,812)
Adjustments to reconcile net loss to net cash used for operating activities:
Amortization	58	78
Depreciation	76	71
Bad debt provision		119
Stock-based compensation	935	464
Amortization of debt discount and debt costs	12	40
Loss on extinguishment of debt		341
Deferred tax expense		1
Change in fair value of convertible debentures		7,464
Changes in operating assets and liabilities:
Accounts receivable	(622)	2,610
Inventory	647	149
Prepaid and other assets	(89)	(72)
Accounts payable	(1,617)	(317)
Accrued expenses	(1,313)	(439)
Deferred revenue	(7)	(113)
Total adjustments	(1,920)	10,396
Net cash used for operating activities	(3,563)	(1,416)
Cash flow from investing activities:
Additions to patents, technology and other		(1)
Additions to property and equipment	(262)	(155)
Net cash used for investing activities	(262)	(156)
Cash flow from financing activities:
Issuance of common stock pursuant to stock option plans	270	196
Issuance of common stock pursuant to Employee Stock Purchase Plan	47
Proceeds from issuance of common stock, net	23,229
Principal repayment of debt financing		(4,638)
Repayment on line of credit		(2,000)
Proceeds from notes payable		7,000
Debt issuance costs		(43)
Net cash provided by financing activities	23,546	515
Increase (decrease) in cash and equivalents	19,721	(1,057)
Cash and cash equivalents, beginning of period	27,186	15,313
Cash and cash equivalents, end of period	46,907	14,256
Supplemental disclosure of cash flow information:
Interest paid	$ 92	122
Taxes paid		26
Issuance of common stock upon conversion of debentures		21,164
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 69