Note 16 - The Financing and Warrant Liabilities - Fair Value of Warrants (Details) $ in Thousands		Dec. 31, 2021 USD ($) yr	Jul. 02, 2021 USD ($)	[1]	Feb. 18, 2021 USD ($) yr	Dec. 31, 2020 USD ($) yr	Dec. 14, 2020 USD ($)	Dec. 31, 2019 USD ($)
Proceeds allocated to warrant liabilities		$ 2,039				$ 1,505		$ 107
Investor Warrants Issued in Connection with 2021 Financing [Member]
Proceeds allocated to warrant liabilities		964			$ 10,476
Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Proceeds allocated to warrant liabilities		132			$ 1,445
Investor Warrants Issued in Connection with 2020 Financing [Member]
Proceeds allocated to warrant liabilities		795				1,279	$ 1,746
Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Proceeds allocated to warrant liabilities		$ 148				224	$ 305
Investor Warrants Issued in Connection with 2018 Financing [Member]
Proceeds allocated to warrant liabilities								71
Placement Agent Warrants Issued in Connection with 2018 Financing [Member]
Proceeds allocated to warrant liabilities			$ 58			$ 2		$ 36
Measurement Input, Share Price [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		1.00			4.48
Measurement Input, Share Price [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		1.00			4.48
Measurement Input, Share Price [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		1.00				1.35	1.25
Measurement Input, Share Price [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		1.00				1.35	1.25
Measurement Input, Share Price [Member] | Investor Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants								1.17
Measurement Input, Share Price [Member] | Placement Agent Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants			1.94			1.35		1.17
Measurement Input, Expected Term [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		2.63			3.50
Measurement Input, Expected Term [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		2.63			3.50
Measurement Input, Expected Term [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		1.95				2.95	3.00
Measurement Input, Expected Term [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		1.95				2.95	3.00
Measurement Input, Expected Term [Member] | Investor Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants								0.55
Measurement Input, Expected Term [Member] | Placement Agent Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants			0.04			0.05		1.05
Measurement Input, Risk Free Interest Rate [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		0.0087			0.0026
Measurement Input, Risk Free Interest Rate [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		0.0087			0.0026
Measurement Input, Risk Free Interest Rate [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		0.0072				0.0017	0.0017
Measurement Input, Risk Free Interest Rate [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		0.0072				0.0017	0.0017
Measurement Input, Risk Free Interest Rate [Member] | Investor Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants								0.0158
Measurement Input, Risk Free Interest Rate [Member] | Placement Agent Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants			0.0005			0.0008		0.0157
Measurement Input, Price Volatility [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		1.15			1.68
Measurement Input, Price Volatility [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		1.15			1.68
Measurement Input, Price Volatility [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		1.28				1.02	1.64
Measurement Input, Price Volatility [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		1.28				1.02	1.64
Measurement Input, Price Volatility [Member] | Investor Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants								0.60
Measurement Input, Price Volatility [Member] | Placement Agent Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants			0.75			0.59		0.80
Measurement Input, Exercise Price [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		3.59			3.59
Measurement Input, Exercise Price [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		4.4875			4.4875
Measurement Input, Exercise Price [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		2.03				2.03	2.03
Measurement Input, Exercise Price [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		2.03				2.03	2.03
Measurement Input, Exercise Price [Member] | Investor Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants	[2]							1.4927
Measurement Input, Exercise Price [Member] | Placement Agent Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants	[2]		1.4927			1.4927		1.4927
Measurement Input, Quoted Price [Member] | Investor Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		0.37			4.02
Measurement Input, Quoted Price [Member] | Placement Agent Warrants Issued in Connection with 2021 Financing [Member]
Fair value of the warrants		0.36			3.96
Measurement Input, Quoted Price [Member] | Investor Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		0.46				0.74	1.01
Measurement Input, Quoted Price [Member] | Placement Agent Warrants Issued in Connection with 2020 Financing [Member]
Fair value of the warrants		0.49				0.74	1.01
Measurement Input, Quoted Price [Member] | Investor Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants								0.11
Measurement Input, Quoted Price [Member] | Placement Agent Warrants Issued in Connection with 2018 Financing [Member]
Fair value of the warrants			0.45			0.02		0.28

[1] The placement agent warrants issued in the 2018 Financing were cashless exercised on July 2, 2021. As a result, the Company issued approximately 0.04 million shares of the Company’s restricted common stock, with a loss of approximately US$0.02million recognized in other income/(loss) account, which represented the difference between the fair value of these warrants on the date of the exercise and the cost of the Company’s restricted common stock issued, based on the close bid price of the Company’s common stock on the same date.

[2] On September 25, 2019, as a result of the close on the first half of an unregistered private placement with a select group of investors, the exercise price of the warrants issued in the 2018 Financing that contain the “full ratchet” price protection in the event of subsequent issuances below the applicable exercise price (the “Down round feature”) was adjusted to US$1.4927.