Note 18 - Net Loss Per Share Attributable to Common Stockholders (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]

	Year Ended December 31,
	2020			2019			2018
Net loss	$	(32,220	)	$	(18,645	)	$	(18,007	)
Series B and C preferred dividend		—			—			(339	)
Net loss attributable to common stockholders	$	(32,220	)	$	(18,645	)	$	(18,346	)
Shares used to compute net loss per share, basic and diluted		88,295,762			21,569,523			6,316,065
Net loss per share attributable to common stockholders, basic and diluted	$	(0.36	)	$	(0.86	)	$	(2.90	)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Year Ended December 31,
	2020		2019		2018
Options to purchase common stock		4,409,806		1,583,575		839,396
Warrants to purchase common stock		14,773,425		17,579,945		9,658
Warrant to purchase convertible preferred stock		—		—		891
Series B and C convertible preferred stock outstanding, including cumulative dividends		—		—		213,760
Series A convertible preferred stock outstanding		—		—		12,260
Convertible promissory notes, related party (as converted)		—		—		185,159
Total potentially dilutive securities excluded from denominator of the diluted earnings per share computation		19,183,231		19,163,520		1,261,124