Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating Activities:
Net loss	$ (9,952)	$ (8,490)
Adjustments to reconcile net loss to cash flows used in operating activities:
Depreciation and amortization	256	151
Stock-based compensation expense, net	736	727
Loss on disposal of property and equipment	0	46
Changes in operating assets and liabilities:
Accounts receivable	(272)	(179)
Inventories	122	(1,104)
Other current assets	(176)	20
Other assets and liabilities	9	112
Accounts payable and accrued expenses	75	(43)
Net cash used in operating activities	(9,202)	(8,760)
Investing Activities:
Purchases of property and equipment	(137)	(69)
Net cash used in investing activities	(137)	(69)
Financing Activities:
Proceeds from public stock offerings, net	18,896	13,040
Proceeds from warrant exercises	1	2,340
Payments on finance lease liability	(14)	(4)
Net cash provided by financing activities	18,883	15,376
Effect of exchange rate changes on cash	(3)	(5)
Net increase in cash and cash equivalents	9,541	6,542
Cash and cash equivalents - beginning of period	14,437	1,279
Cash and cash equivalents - end of period	23,978	7,821
Supplemental cash flow information
Inventory transferred to property, plant and equipment	179	112
Equipment acquired through finance lease liability	$ 0	$ 67