Note 13 - Stock Based Compensation (Tables)

3 Months Ended

Mar. 31, 2020

Notes Tables

Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block]

January 1,	Number of shares
2012		2,502
2013		2,871
2014		4,128
2015		5,463
2016		7,257
2017		12,623
2018		106,076
2019		233,862
2020		365,239
Total additional shares		740,021

Share-based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Underlying Shares		Weighted- Average Exercise Price Per Share		Weighted- Average Contractual Life Remaining in Years		Aggregate Intrinsic Value
Outstanding as of January 1, 2020		4,308,383	$	3.44				-
Granted		-		-				-
Forfeited		-		-				-
Expired		-		-				-
Outstanding as of March 31, 2020		4,308,383		3.44		8.80	$	-
Exercisable as of March 31, 2020		3,832,000		3.58		8.80	$	-
Vested and expected to vest		4,308,383	$	3.44		8.80	$	-

Liability Options [Member]

Notes Tables

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	January 13,
	2019
Risk free interest rate		2.53	%
Expected term (in years)		4.50-5.00
Stock price	$	1.36
Dividend yield		-	%
Expected volatility		121.0-123.0	%

Share-based Payment Arrangement, Option [Member]

Notes Tables

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	Three Months Ended March 31,
	2020		2019
General and administrative	$	483,000	$	224,676
Research and development		204,752		51,157
Total stock compensation expense	$	687,752	$	275,833

	Period Ended March 31, 2019
General and administrative	$	1,074,183
Research and development		667,736
Total stock compensation expense	$	1,741,919