Note 14 - Warrant Liabilities- Fair Value of Warrants (Details) $ in Thousands	Mar. 31, 2023 USD ($) yr	Dec. 31, 2022 USD ($) yr		Mar. 31, 2022 USD ($) yr		Dec. 31, 2021 USD ($) yr
Warrant liabilities as of the closing date	$ 84	$ 185		$ 1,244		$ 2,039
Investor Warrants Issued in Connection with 2021 Financing [Member]
Warrant liabilities as of the closing date	49	86		626		964
Investor Warrants Issued in Connection with 2020 Financing [Member]
Warrant liabilities as of the closing date	25	76		449		795
Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Warrant liabilities as of the closing date	5	9		84		132
Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Warrant liabilities as of the closing date	$ 5	$ 14		$ 85		$ 148
Measurement Input, Share Price [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	1.70	0.46		0.73	[1]	1.00	[1]
Measurement Input, Share Price [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	1.70	0.46		0.73	[1]	1.00	[1]
Measurement Input, Share Price [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	1.70	0.46		0.73	[1]	1.00	[1]
Measurement Input, Share Price [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	1.70	0.46		0.73	[1]	1.00	[1]
Measurement Input, Expected Term [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants | yr	1.38	1.63		2.38		2.63
Measurement Input, Expected Term [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants | yr	0.70	0.95		1.70		1.95
Measurement Input, Expected Term [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants | yr	1.38	1.63		2.38		2.63
Measurement Input, Expected Term [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants | yr	0.70	0.95		1.70		1.95
Measurement Input, Risk Free Interest Rate [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	0.0444	0.04625		0.0235		0.0087
Measurement Input, Risk Free Interest Rate [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	0.0480	0.04716		0.0223		0.0072
Measurement Input, Risk Free Interest Rate [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	0.0444	0.04625		0.0235		0.0087
Measurement Input, Risk Free Interest Rate [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	0.0480	0.04716		0.0223		0.0072
Measurement Input, Expected Dividend Rate [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	0	0		0		0
Measurement Input, Expected Dividend Rate [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	0	0		0		0
Measurement Input, Expected Dividend Rate [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	0	0		0		0
Measurement Input, Expected Dividend Rate [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	0	0		0		0
Measurement Input, Price Volatility [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	1.13	0.9974		1.21		1.15
Measurement Input, Price Volatility [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	1.25	1.1561		1.27		1.28
Measurement Input, Price Volatility [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	1.13	0.9974		1.21		1.15
Measurement Input, Price Volatility [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	1.25	1.1561		1.27		1.28
Measurement Input, Exercise Price [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	17.95	3.59	[1]	3.59		3.59
Measurement Input, Exercise Price [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	10.15	2.03	[1]	2.03		2.03
Measurement Input, Exercise Price [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	22.4375	4.4875	[1]	4.4875		4.4875
Measurement Input, Exercise Price [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	10.15	2.03	[1]	2.03		2.03
Measurement Input, Quoted Price [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	0.0937	0.0329		0.24		0.37
Measurement Input, Quoted Price [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	0.0731	0.0439		0.26		0.46
Measurement Input, Quoted Price [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants	0.0727	0.0256		0.23		0.36
Measurement Input, Quoted Price [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants	0.0760	0.0456		0.28		0.49

[1] To reflect the actual inputs used for the determination of fair value of the Warrants, the stock prices and exercise prices presented were not retrospectively restated for effect of the 1-for-5 reverse stock split effective on January 18, 2023, see Note 4(g).