Note 7 - Embedded Derivatives Liabilities (Tables)

3 Months Ended

Mar. 31, 2021

Notes Tables

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

	Issuance Date	Expiration Date	Exercise Price as of March 31, 2021		Shares Underlying Warrants on Issuance Date	Shares Issued upon Warrant Exercises as of March 31, 2021	Shares Underlying Warrants Outstanding as of March 31, 2021
Series F Warrants	04/01/2016	04/01/2021	$	40.00	25,733	11,692	14,041
Series I Warrants	09/13/2016	09/13/2021	$	220.00	35,368	—	35,368
Series K Warrants	02/17/2017	2/17/2022	$	2.00	315,986	308,660	7,326
Series 2020-A Warrants (1)	7/6/2020	7/6/2025	$	0.60	30,000,000	29,905,892	94,108
					30,377,087	30,226,244	150,843

Exercise of Warrants [Table Text Block]

	Common Stock Issued		Proceeds
Series 2020-A Warrants		1,863,058	$	1,117