Note 14 - Stock Based Compensation (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

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, 2021		7,067,436	$	2.74		-	$
Granted		-		-		-
Exercised		-		-		-
Forfeited		-		-		-
Expired		-		-		-		-
Outstanding as of March 31, 2021		7,067,436		2.74		8.36	$	3,865,800
Exercisable as of March 31, 2021		5,108,435		3.05		8.09	$	2,943,244
Vested and expected to vest		7,067,436	$	2.74		8.36	$	3,865,800

Share-based Payment Arrangement, Option [Member]

Notes Tables

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

	Three Months Ended March 31,
	2021		2020
General and administrative	$	449,944	$	483,000
Research and development		189,807		204,752
Total stock compensation expense	$	639,751	$	687,752