Note 3 - Warrants (Tables)

3 Months Ended

Mar. 31, 2023

Notes Tables

Schedule of Warrants or Rights, Assumptions Used [Table Text Block]

	March 31, 2023	December 31, 2022
Risk-free interest rate	4.0% to 4.9%	4.2% to 4.8%
Volatility	58.4% to 67.6%	63.1% to 76.3%
Expected life (years)	0.1 to 2.4	0.1 to 2.6
Dividend yield	—%	—%

Schedule of Warrant Activity [Table Text Block]

	Number of Shares			Range of Warrant Exercise				Weighted Average		Weighted Average Remaining Contractual
	Under Warrant			Price per Share				Exercise Price		Life (Years)
Balance at January 1, 2023		2,656,296		$	6.30	$	16.80	$	9.49		1.7
Expired warrants		(21,450	)	$	16.80	$	16.80	$	16.80		—
Balance at March 31, 2023		2,634,846		$	6.30	$	16.80	$	9.43		1.4
Exercisable at March 31, 2023		2,634,846		$	6.30	$	16.80	$	9.43		1.4