Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accounts receivable, allowance for doubtful accounts	$ 124	$ 407
Convertible preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	75,000,000	75,000,000
Common stock, shares issued (in shares)	2,171,316	707,571
Common stock, shares outstanding (in shares)	2,171,316	707,571
Series A Preferred Stock [Member]
Convertible preferred stock, shares authorized (in shares)	547,345
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, shares issued (in shares)	0	185,218
Convertible preferred stock, shares outstanding (in shares)	0	185,218
Series B Preferred Stock [Member]
Convertible preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Convertible preferred stock, shares issued (in shares)	35,819	31,678
Convertible preferred stock, shares outstanding (in shares)	35,819	31,678