Note 9 - Stockholders' Equity, Stock Options and Warrants - Schedule of Listing of Stock Options and Warrants (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Shares, options (in shares)	47,664
Shares, warrants (in shares)	1,806,589	1,816,437	1,584,995
Price, options (in dollars per share)	$ 82.23
Price, warrants (in dollars per share)	21.52	$ 22.6	$ 33.2
Minimum [Member]
Price, options (in dollars per share)	3.44
Price, warrants (in dollars per share)	14
Maximum [Member]
Price, options (in dollars per share)	69,375
Price, warrants (in dollars per share)	$ 200
Warrants 2019 [Member]
Shares, warrants (in shares)	84,514
Warrants 2019 [Member] | Minimum [Member]
Price, warrants (in dollars per share)	$ 16.9
Warrants 2019 [Member] | Maximum [Member]
Price, warrants (in dollars per share)	$ 200
Warrants 2020 [Member]
Shares, warrants (in shares)	65,586
Warrants 2020 [Member] | Minimum [Member]
Price, warrants (in dollars per share)	$ 36
Warrants 2020 [Member] | Maximum [Member]
Price, warrants (in dollars per share)	$ 59.84
Warrants 2021 [Member]
Shares, warrants (in shares)	603,353
Warrants 2021 [Member] | Minimum [Member]
Price, warrants (in dollars per share)	$ 16
Warrants 2021 [Member] | Maximum [Member]
Price, warrants (in dollars per share)	$ 48.75
Warrants 2022 [Member]
Shares, warrants (in shares)	1,053,136
Warrants 2022 [Member] | Minimum [Member]
Price, warrants (in dollars per share)	$ 14
Warrants 2022 [Member] | Maximum [Member]
Price, warrants (in dollars per share)	$ 15
Stock Options 2014 [Member]
Shares, options (in shares)	3
Stock Options 2014 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 32,500
Stock Options 2014 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 69,375
Stock Options 2015 [Member]
Shares, options (in shares)	12
Stock Options 2015 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 30.8
Stock Options 2015 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 17,250
Stock Options 2016 [Member]
Shares, options (in shares)	296
Stock Options 2016 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 30.8
Stock Options 2016 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 850
Stock Options 2017 [Member]
Shares, options (in shares)	10,478
Stock Options 2017 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 30.8
Stock Options 2017 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 420
Stock Options 2018 [Member]
Shares, options (in shares)	2,893
Stock Options 2018 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 30.8
Stock Options 2018 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 226
Stock Options 2019 [Member]
Shares, options (in shares)	14,970
Stock Options 2019 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 30.8
Stock Options 2019 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 158
Stock Options 2020 [Member]
Shares, options (in shares)	14,883
Stock Options 2020 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 14.65
Stock Options 2020 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 32.8
Stock Options 2021 [Member]
Shares, options (in shares)	2,248
Stock Options 2021 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 14.4
Stock Options 2021 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 29.4
Stock Options 2022 [Member]
Shares, options (in shares)	846
Stock Options 2022 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 7.7
Stock Options 2022 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 14.65
Stock Options 2023 [Member]
Shares, options (in shares)	1,035
Stock Options 2023 [Member] | Minimum [Member]
Price, options (in dollars per share)	$ 3.44
Stock Options 2023 [Member] | Maximum [Member]
Price, options (in dollars per share)	$ 7.68