Note 9 - Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2020

Notes Tables

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

	Three Months Ended September 30,						Nine Months Ended September 30,
	2020			2019			2020			2019
Numerator
Net loss attributable to common shareholders	$	(3,491,071	)	$	(3,285,914	)	$	(10,344,633	)	$	(14,621,750	)
Denominator
Weighted average common shares outstanding used to compute net loss per share, basic and diluted		10,162,770			9,130,057			9,496,222			8,283,302
Net loss per share of common stock, basic and diluted:	$	(0.34	)	$	(0.36	)	$	(1.09	)	$	(1.77	)

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
Options to purchase common stock		7,158,387		4,348,383		5,825,082		2,572,413
Series B convertible preferred stock		177,562		191,543		183,544		281,015
Warrants to purchase common stock		1,070,028		1,070,028		1,070,028		1,828,085
		8,405,977		5,609,954		7,078,654		4,681,513