Note 9 - Stockholders' Equity, Stock Options and Warrants (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

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

	Year Ended December 31,
	2023		2022
	Stock Options
Expected dividend yield		0.0%		0.0%
Expected stock price volatility		90.8% –98.2%		86.5% –92.2%
Risk-free interest rate		3.38% –3.95%		1.83% –4.26%
Expected life (years)	10		10
	Warrants
Expected dividend yield		0.0%		0.0%
Expected stock price volatility		0%		92.2%
Risk-free interest rate		0%		2.96% –2.97%
Expected life (years)	0		5 – 5.5

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

	Stock Options					Warrants
	Number of Shares			Average Exercise Price		Number of Shares			Average Exercise Price
Outstanding at December 31, 2021		53,144		$	96.60		1,584,995		$	33.20
Issued		1,599			8.40		1,053,136			14.00
Forfeited		(2,013	)		17.60		-			-
Expired		(3,677	)		208.40		(5,422	)		329.60
Cancelled		-			-		(816,272	)		30.20
Outstanding at December 31, 2022		49,053		$	91.60		1,816,437		$	22.60
Issued		1,075			5.45		-			-
Forfeited		(49	)		6.18		-			-
Expired		(2,415	)		139.30		(9,848	)		219.60
Outstanding at December 31, 2023		47,664		$	82.23		1,806,589		$	21.52

Schedule of Share-based Compensation Shares Authorized Under Stock Option and Warrant Plans by Exercise Price Range [Table Text Block]

Range of Exercise Prices		Shares		Weighted Average Remaining Life
Options
$	3.44 –14.65		12,029		6.67
$	16.28 –29.40		4,935		7.57
$	30.80 –52.20		16,049		4.13
$	101.00 –69,375.00		14,651		3.52
Total			47,664
Warrants:
$	14.00 –20.00		1,168,465		3.62
$	21.05 –30.00		368,246		2.06
$	34.38 –40.00		180,314		5.87
$	43.75 –200.00		89,564		1.83
Total			1,806,589

Disclosure of Share-Based Compensation Arrangements by Share-Based Payment Award [Table Text Block]

Year	Shares		Range of Exercise Prices
2014		3	$	32,500.00	–		69,375.00
2015		12		30.80	–		17,250.00
2016		296		30.80	–		850.00
2017		10,478		30.80	–		420.00
2018		2,893		30.80	–		226.00
2019		14,970		30.80	–		158.00
2020		14,883		14.65	–		32.80
2021		2,248		14.40	–		29.40
2022		846		7.70	–		14.65
2023		1,035		3.44	–		7.68
Total		47,664	$	3.44	–	$	69,375.00

Year	Shares		Range of Exercise Prices
2019		84,514	$	16.90	–		200.00
2020		65,586		36.00	–		59.84
2021		603,353		16.00	–		48.75
2022		1,053,136		14.00	–		15.00
Total		1,806,589	$	14.00	–	$	200.00