Note 8 - Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2018

Notes Tables

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

	Three Months Ended September 30,						Nine months Ended September 30,
	2018			2017			2018			2017
Net Loss Per Share
Numerator
Net loss	$	(3,309,866	)	$	(2,184,510	)	$	(9,326,825	)	$	(6,129,553	)
Deemed dividend attributable to preferred stock								(11,479,308	)		(2,568,132	)
Net loss attributable to common shareholders	$	(3,309,866	)	$	(2,184,510	)	$	(20,806,133	)	$	(8,697,685	)
Denominator
Weighted average common shares outstanding		5,183,492			1,034,262			3,645,682			657,184
Basic and diluted net loss per share	$	(0.64	)	$	(2.11	)	$	(5.71	)	$	(13.23	)

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

	Three Months Ended September 30,				Nine months Ended September 30,
	2018		2017		2018		2017
Options to purchase common stock		783,794		176,502		388,377		100,505
Series A convertible preferred stock				42,480				74,651
Series B convertible preferred stock		1,338,916				751,332
Warrants to purchase common stock		4,716,935		138,365		2,644,946		227,229
Total		6,839,645		357,347		3,784,655		402,385