Note 5 - Share-based Compensation (Tables)

9 Months Ended

Sep. 30, 2021

Notes Tables

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

Risk-Free interest rate	0.13% - 0.85%
Expected dividend yield	—%
Expected stock price volatility	54.52% - 60.53%
Expected life of options (in years)	2.00 - 6.25

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

						Weighted-Average
				Weighted-Average		Remaining Contractual		Aggregate Intrinsic
	Shares			Exercise Price		Term (Years)		Value
Outstanding at December 31, 2020		4,638,390		$	2.44		5.64	$	13,701,610
Granted (1)		770,825			5.24
Exercised		(585,000	)		1.68
Expired		—			—
Canceled		—			—
Outstanding at September 30, 2021		4,824,215		$	2.98		6.14	$	12,537,900
Exercisable at September 30, 2021		3,500,516		$	2.37		5.28	$	11,191,507

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

	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
General and administrative	$	405,383	$	354,264	$	1,183,568	$	1,125,217
Research and development		51,826		46,417		140,832		139,016
Total	$	457,209	$	400,681	$	1,324,400	$	1,264,233