Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Revenues:
Product sales	$ 1,612	$ 1,719	$ 4,042	$ 4,997
Other revenue	89	86	422	283
Total revenues	1,701	1,805	4,464	5,280
Cost of revenues:
Products and services	790	1,094	2,430	3,276
Product line exit expense	0	0	0	747
Total cost of revenues	790	1,094	2,430	4,023
Gross profit	911	711	2,034	1,257
Operating expenses:
Selling, general and administrative	3,586	4,654	11,952	16,210
Research and development	1,236	2,076	4,210	4,303
Total operating expenses	4,822	6,730	16,162	20,513
Loss from operations	(3,911)	(6,019)	(14,128)	(19,256)
Other income (expense):
Investment income	34	13	36	22
Other	12	15	10	14
Nonoperating Income (Expense), Total	46	28	46	36
Net loss	$ (3,865)	$ (5,991)	$ (14,082)	$ (19,220)
Net loss per basic and diluted common share (in dollars per share)	$ (0.09)	$ (0.15)	$ (0.34)	$ (0.50)
Weighted average common shares used to compute net loss per basic and diluted common share (in shares)	41,086,285	40,413,332	40,955,234	38,767,009
Comprehensive loss:
Net loss	$ (3,865)	$ (5,991)	$ (14,082)	$ (19,220)
Net unrealized gain (loss) on short-term investments	73	(2)	62	(4)
Comprehensive loss	$ (3,792)	$ (5,993)	$ (14,020)	$ (19,224)