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

12 Months Ended

Dec. 31, 2021

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, 2019		766,424		$	11.34		2,171,610		$	15.26
Issued		319,851			1.03		8,097,468			1.55
Forfeited		(72,728	)		10.58		(128,710	)		95.11
Exercised		-			-		(2,786,992	)		0.79
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

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:
0.72 – 1.10		335,876		9.31
$1.15 – 1.64		356,673		8.36
$2.610 – 8.41		214,937		8.15
$10.10 – 5,962.50		155,385		5.99
Total		1,062,871
Warrants:
$0.80-1.72		21,468,599		3.31
$1.80 – 2.18		8,451,287		4.50
$2.25 – 10.00		1,555,778		3.37
$10.71 – 22.50		224,221		2.94
Total		31,699,885

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

Year	Shares		Price
2012		114		$1.54	–	$1,500.00
2013		146		1.54	–	5,962.50
2014		84		1.54	–	3,468.75
2015		394		1.54	–	862.50
2016		9,174		1.54	–	42.50
2017		214,555		1.54	–	21.00
2018		78,325		1.54	–	13.50
2019		314,963		1.54	–	7.50
2020		303,199		0.73	–	3.48
2021		141,917		0.72	–	1.47
Total		1,062,871		$0.72	–	$5,962.50

Year	Shares		Price
2017		108,435		$10.71	–	$22.50
2018		196,946		8.36	–	13.125
2019		1,690,286		0.845	–	11.80
2020		2,010,144		0.845	–	2.992
2021		27,694,074		0.80	–	2.992
Total		31,699,885		$0.80	–	$22.50