Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Total revenue	$ 10,280	$ 10,108
Cost of sales	4,295	4,757
Gross profit	5,985	5,351
Operating expenses:
Research and development	2,439	3,030
General and administrative	2,843	2,800
Sales and marketing	987	1,103
Total operating expenses	6,269	6,933
Loss from operations	(284)	(1,582)
Interest expense	(152)	(172)
Other (expense) income, net	(15)	48
Net loss before income taxes	(451)	(1,706)
Income tax expense	(9)	(26)
Net loss and comprehensive loss	$ (460)	$ (1,732)
Net loss per common share, basic and diluted	$ (0.02)	$ (0.10)
Weighted-average shares used to compute net loss per common share, basic and diluted	19,092,367	18,055,693
Product sales
Total revenue	$ 9,068	$ 9,635
Licensing, royalty and other revenue
Total revenue	$ 1,212	$ 473