Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenues:
Product sales	$ 1,719	$ 988	$ 4,997	$ 2,486
Other revenue	86	19	283	43
Total revenues	1,805	1,007	5,280	2,529
Cost of revenues:
Products and services	1,094	688	3,276	1,659
Product line exit expense	0	0	747	0
Total cost of revenues	1,094	688	4,023	1,659
Gross profit	711	319	1,257	870
Operating expenses:
Selling, general and administrative	4,654	3,255	16,210	7,933
Research and development	2,076	927	4,303	2,038
Total operating expenses	6,730	4,182	20,513	9,971
Loss from operations	(6,019)	(3,863)	(19,256)	(9,101)
Other income (expense):
Investment income	13	5	22	81
Other	15	(4)	14	(4)
Nonoperating Income (Expense), Total	28	1	36	77
Net loss	$ (5,991)	$ (3,862)	$ (19,220)	$ (9,024)
Net loss per basic and diluted common share (in dollars per share)	$ (0.15)	$ (0.11)	$ (0.50)	$ (0.28)
Weighted average common shares used to compute net loss per basic and diluted common share (in shares)	40,413,332	36,419,771	38,767,009	32,653,408
Comprehensive loss:
Net loss	$ (5,991)	$ (3,862)	$ (19,220)	$ (9,024)
Net unrealized gain (loss) on short-term investments	(2)	7	(4)	7
Comprehensive loss	$ (5,993)	$ (3,855)	$ (19,224)	$ (9,017)