Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenues	$ 2,132	$ 2,802	$ 4,020	$ 5,361
Cost of revenues	1,475	1,784	2,839	3,449
Gross profit	657	1,018	1,181	1,912
Operating expenses:
Research and development	1,086	1,507	2,158	3,105
Selling, general and administrative	3,330	3,918	7,478	7,863
Total operating expenses	4,416	5,425	9,636	10,968
Loss from operations	(3,759)	(4,407)	(8,455)	(9,056)
Interest expense, net	(440)	(399)	(879)	(795)
Other (expenses) income, net	(15)	2,354	(20)	2,347
Net loss and comprehensive loss	(4,214)	(2,452)	(9,354)	(7,504)
Accretion of preferred stock dividends	(1,127)	(1,044)	(2,254)	(2,088)
Deemed dividend arising from beneficial conversion feature of convertible preferred stock	0	0	(5,111)	0
Net loss applicable to common stockholders	$ (5,341)	$ (3,496)	$ (16,719)	$ (9,592)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.94)	$ (0.73)	$ (3.16)	$ (2.05)
Weighted average common shares used to compute net loss per share, basic and diluted (in shares)	5,702	4,768	5,298	4,670