Note 10 - Net Loss Per Share (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

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

	Year Ended December 31,
	2018			2017
Numerator
Net loss	$	(11,404,934	)	$	(8,122,581	)
Deemed dividend attributable to preferred stock		(11,479,308	)		(2,568,132	)
Net loss attributable to common shareholders	$	(22,884,242	)	$	(10,690,713	)
Denominator
Weighted average common shares outstanding used to compute net loss per share, basic and diluted		4,157,746			974,773
Net loss per share of common stock, basic and diluted:	$	(5.50	)	$	(10.97	)

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

	Year Ended December 31,
	2018		2017
Options to purchase common stock		487,941		117,301
Series A convertible preferred stock				55,835
Series B convertible preferred stock		774,983
Warrants to purchase common stock		3,054,481		202,063
		4,317,405		375,199