Note 3 - Warrants (Tables)

6 Months Ended

Jun. 30, 2023

Notes Tables

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

	June 30, 2023	December 31, 2022
Risk-free interest rate	4.8% to 5.5%	4.2% to 4.8%
Volatility	61.1% to 70.9%	63.1% to 76.3%
Expected life (years)	0.1 to 2.1	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		(26,914	)	$	13.92	$	16.80	$	16.22		—
Balance at June 30, 2023		2,629,382		$	6.30	$	16.80	$	9.42		1.2
Exercisable at June 30, 2023		2,629,382		$	6.30	$	16.80	$	9.42		1.2