Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenues:
Product sales	$ 1,034	$ 969	$ 1,650	$ 2,431
Other revenue	168	196	263	333
Total revenues	1,202	1,165	1,913	2,764
Cost of revenues	534	708	893	1,640
Gross profit	668	457	1,020	1,124
Operating expenses:
Selling, general and administrative	4,745	3,764	8,286	8,370
Research and development	1,002	1,476	2,073	2,971
Total operating expenses	5,747	5,240	10,359	11,341
Loss from operations	(5,079)	(4,783)	(9,339)	(10,217)
Other income (expense):
Interest income	88	0	324	2
Other	(16)	(2)	(20)	(2)
Total other income (expense)	72	(2)	304	0
Net loss	$ (5,007)	$ (4,785)	$ (9,035)	$ (10,217)
Net loss per basic and diluted common share (in dollars per share)	$ (0.12)	$ (0.12)	$ (0.22)	$ (0.25)
Weighted average common shares used to compute net loss per basic and diluted common share (in shares)	41,709,718	40,978,820	41,483,669	40,943,241
Comprehensive loss:
Net loss	$ (5,007)	$ (4,785)	$ (9,035)	$ (10,217)
Net unrealized gain (loss) on short-term investments	0	12	0	(11)
Comprehensive loss	$ (5,007)	$ (4,773)	$ (9,035)	$ (10,228)