Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common stock and paid-in capital	Accumulated other comprehensive loss	Accumulated deficit
Balance at Dec. 31, 2019		$ 58,537	$ (176)	$ (13,883)
Issuance of common stock		4,764
Issuance of warrants and senior convertible notes
Share-based compensation expense		63
Proceeds from employee stock purchase plan		14
Unrealized gain (loss) on available-for-sale securities, net of tax			8
Foreign currency translation adjustment	$ (18)		(18)
Net income (loss)	505			505
Balance at Dec. 31, 2020	49,814	63,378	(186)	(13,378)
Issuance of common stock		9,288
Issuance of warrants and senior convertible notes
Share-based compensation expense		136
Proceeds from employee stock purchase plan		15
Unrealized gain (loss) on available-for-sale securities, net of tax			(28)
Foreign currency translation adjustment	(27)		(27)
Net income (loss)	(7,694)			(7,694)
Balance at Dec. 31, 2021	$ 51,504	$ 72,817	$ (241)	$ (21,072)