Condensed Statements of Changes in Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Series A Preferred Convertible Stock Preferred Stock.	Common stock	Additional paid-in capital	Accumulated deficit	Total
Balance at Dec. 31, 2019	$ 38,894		$ 927	$ (36,557)	$ (35,630)
Balance (shares) at Dec. 31, 2019	4,443,259	1,099,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			302		302
Exercise of common stock warrants			7		7
Exercise of common stock warrants (shares)		25,346
Net loss				(13,764)	(13,764)
Balance at Sep. 30, 2020			1,236	(50,321)	(49,085)
Balance (shares) at Sep. 30, 2020		1,124,616
Increase (Decrease) in Temporary Equity [Roll Forward]
Sale of Series A convertible preferred stock and warrants	$ 9,475
Sale of Series A convertible preferred stock and warrants (shares)	1,226,925
Balance at Sep. 30, 2020	$ 48,369
Balance (shares) at Sep. 30, 2020	5,670,184
Balance at Jun. 30, 2020			1,115	(41,944)	(40,829)
Balance (shares) at Jun. 30, 2020		1,112,393
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation expense			117		117
Exercise of common stock warrants			4		4
Exercise of common stock warrants (shares)		12,223
Net loss				(8,377)	(8,377)
Balance at Sep. 30, 2020			1,236	(50,321)	(49,085)
Balance (shares) at Sep. 30, 2020		1,124,616
Balance at Jun. 30, 2020	$ 48,391
Balance (shares) at Jun. 30, 2020	5,670,184
Increase (Decrease) in Temporary Equity [Roll Forward]
Series A convertible preferred stock issuance cost	$ (22)
Balance at Sep. 30, 2020	$ 48,369
Balance (shares) at Sep. 30, 2020	5,670,184
Balance at Dec. 31, 2020		$ 1	95,738	(54,394)	41,345
Balance (shares) at Dec. 31, 2020		10,634,245
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Sale of common stock and common stock warrants			26,666		26,666
Sale of common stock and common stock warrants, shares		1,014,115
Share-based compensation expense			2,229		2,229
Exercise of common stock warrants			1,338		1,338
Exercise of common stock warrants (shares)		193,975
Exercise of stock options and vesting of restricted stock			74		74
Exercise of stock options and vesting of restricted stock		250,998
Net loss				(16,859)	(16,859)
Balance at Sep. 30, 2021		$ 1	126,045	(71,253)	54,793
Balance (shares) at Sep. 30, 2021		12,093,333
Balance at Jun. 30, 2021		$ 1	124,149	(63,533)	60,617
Balance (shares) at Jun. 30, 2021		11,812,792
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Sale of common stock and common stock warrants			262		262
Sale of common stock and common stock warrants, shares		14,115
Share-based compensation expense			1,155		1,155
Exercise of common stock warrants			432		432
Exercise of common stock warrants (shares)		47,958
Exercise of stock options and settlement of RSUs			47		47
Exercise of stock options and settlement of RSUs (shares)		218,468
Net loss				(7,720)	(7,720)
Balance at Sep. 30, 2021		$ 1	$ 126,045	$ (71,253)	$ 54,793
Balance (shares) at Sep. 30, 2021		12,093,333