Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenues:
Product sales	$ 1,462	$ 1,427
Other revenue	137	115
Total revenues	1,599	1,542
Cost of revenues	932	937
Gross profit	667	605
Operating expenses:
Selling, general and administrative	4,606	4,978
Research and development	1,495	1,065
Total operating expenses	6,101	6,043
Loss from operations	(5,434)	(5,438)
Other income (expense):
Interest income	2	2
Other	0	7
Nonoperating Income (Expense), Total	2	9
Net loss	$ (5,432)	$ (5,429)
Net loss per basic and diluted common share (in dollars per share)	$ (0.13)	$ (0.14)
Weighted average common shares used to compute net loss per basic and diluted common share (in shares)	40,907,266	37,618,629
Comprehensive loss:
Net loss	$ (5,432)	$ (5,429)
Net unrealized gain (loss) on short-term investments	(23)	2
Comprehensive loss	$ (5,455)	$ (5,427)