Note 4 - Stockholders' Equity, Stock Options and Warrants (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

Sales of Stock [Table Text Block]

Offering Closing Date	Shares		Sale Price per Share*		Investor Warrants		Exercise Price per Share – investor Warrants		Placement Agent Warrants		Exercise Price per Share – Placement Agent Warrants		Gross Proceeds of Offering		Net Proceeds of Offering
January 12, 2021 (registered direct)		3,650,840	$	0.842		1,825,420	$	0.80		273,813	$	1.0525	$	3,074,007	$	2,731,767
January 21, 2021 (registered direct)		2,200,000	$	1.00		1,100,000	$	1.00		165,000	$	1.25	$	2,200,000	$	1,932,050
January 26, 2021 (registered direct)		3,414,970	$	1.20		1,707,485	$	1.20		256,123	$	1.50	$	4,097,964	$	3,668,687
February 16, 2021 (registered direct)		4,222,288	$	1.75		2,111,144	$	2.00		316,672	$	2.1875	$	7,389,004	$	6,679,989
February 23, 2021 (private placement)		9,043,766	$	1.95		4,521,883	$	2.00		678,282	$	2.4375	$	17,635,344	$	16,064,739
June 16, 2021 (registered direct)		15,520,911	$	1.375		15,520,911	$	1.25		1,164,068	$	1.71875	$	21,341,252	$	19,446,296
Total		38,057,775				26,786,843				2,853,958			$	55,737,571	$	50,523,528

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, 2020		1,013,547		$	5.41		7,353,376		$	1.99
Issued		147,230			1.06		29,640,801			1.44
Forfeited		(92,593	)		8.64		-			-
Expired		-			-		(25,233	)		10.00
Exercised		(5,313	)		0.74		(5,269,059	)		0.86
Outstanding at December 31, 2021		1,062,871		$	4.83		31,699,885		$	1.66
Issued		31,970			0.42		21,062,714			0.70
Forfeited		(40,241	)		0.88		-			-
Expired		(73,540	)		10.42		(108,435	)		16.48
Cancelled		-			-		(16,325,433	)		1.51
Outstanding at December 31, 2022		981,060		$	4.58		36,328,731		$	1.13

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:
$	0.26 –0.81		266,382		8.10
$	1.02 –1.25		50,795		8.82
$	1.25 –1.64		318,686		5.99
$	2.610 –7.90		208,040		6.49
$	10.10 –5,962.50		137,157		4.55
Total			981,060
Warrants:
$	0.70 –0.80		21,626,850		4.83
$	0.84 –1.72		10,271,436		1.68
$	1.80 –2.18		2,758,881		3.37
$	2.25 –10.00		1,555,778		2.51
$	10.71 –22.50		115,786		2.25
Total			36,328,731

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

Year	Shares		Price
2013		123	$	1.54	–		5,962.50
2014		84		1.54	–		3,468.75
2015		239		1.54	–		862.50
2016		6,641		1.54	–		42.50
2017		214,555		1.54	–		21.00
2018		57,868		1.54	–		13.50
2019		306,663		1.54	–		7.50
2020		297,669		0.73	–		3.48
2021		76,812		0.72	–		1.47
2022		20,406		0.26	–		0.7361
Total		981,060	$	0.40	–	$	5,962.50

Year	Shares		Price
2018		196,946	$	8.36	–		13.13
2019		1,690,286		0.85	–		11.80
2020		1,311,731		0.85	–		2.99
2021		12,067,054		0.80	–		2.44
2022		21,062,714		0.70	–		0.75
Total		36,328,731	$	0.70	–	$	13.13