Note 8 - Stock Based Awards (Tables)

6 Months Ended

Jun. 30, 2022

Notes Tables

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

						Weighted
						Average
				Weighted		Remaining		Aggregate
				Average		Contractual		Intrinsic
	Number of			Exercise		Life		Value
	Shares			Price		(in years)		(in thousands)
Balances, January 1, 2022		2,439,253		$	3.96
Options granted		1,913,200			1.97
Options cancelled		(407,000	)		3.78
Options exercised		—			—
Balances, June 30, 2022		3,945,453		$	3.01		7.1	$	501
Outstanding and expected to vest as of June 30, 2022		3,568,032		$	3.05		7.0	$	501
Exercisable as of June 30, 2022		1,979,763		$	3.00		5.3	$	501

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

	June 30,			June 30,
	2022			2021
Expected volatility		112.0	%		113.4	%
Risk-free interest rate		1.8	%		0.7	%
Dividend yield		0.0	%		0.0	%
Expected life (in years)		6.1			6.1