Note 1 - Organization and Nature of Operations (Details Textual)					12 Months Ended
	Oct. 25, 2024 $ / shares shares	Oct. 24, 2024 USD ($) $ / shares shares	Aug. 30, 2024 USD ($) shares	Jul. 15, 2024 $ / shares shares	Dec. 31, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Aug. 23, 2024	Jul. 31, 2024 USD ($)	Jan. 09, 2023 shares	Jan. 08, 2023 shares
Common Stock, Shares Authorized (in shares)				30,000,000	30,000,000	30,000,000
Common Stock, Par or Stated Value Per Share (in dollars per share) | $ / shares				$ 0.0001	$ 0.0001	$ 0.0001
Cash and Cash Equivalents, at Carrying Value | $					$ 2,873,000	$ 3,565,000
Net Cash Provided by (Used in) Operating Activities | $					(9,271,000)	(20,619,000)
Retained Earnings (Accumulated Deficit) | $					$ (292,352,000)	(275,709,000)
Class of Warrant or Right, Exercised in Period (in shares)					6,209,979
Series E Warrants [Member]
Class of Warrant or Right, Exercised in Period (in shares)	33,160.8	33,160.8
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)									33,161
Series F Warrants [Member]
Class of Warrant or Right, Exercised in Period (in shares)	499,909.34	499,909.34
Series G Warrants [Member]
Class of Warrant or Right, Exercised in Period (in shares)	499,909.34	499,909.34
Series H Warrants [Member]
Class of Warrant or Right, Exercised in Period (in shares)	1,990,000	1,990,000
Series I Warrants [Member]
Class of Warrant or Right, Exercised in Period (in shares)	2,325,000	2,325,000
Existing Warrants [Member]
Stock Issued During Period, Shares, Warrant Exercises (in shares)	5,347,981	5,347,981
Class of Warrant or Right, Exercised During Period, Exercise Price (in dollars per share) | $ / shares	$ 0.7	$ 0.7
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)										33,161
Series K Warrants [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	10,695,962	10,695,962
Underwriting Agreement [Member]
Stock Issued During Period, Value, New Issues | $			$ 3,600,000
Payments of Stock Issuance Costs | $			$ 1,000,000
The 2024 Inducement Offer [Member]
Stock Issued During Period, Value, New Issues | $					$ 3,356,000
Payments of Stock Issuance Costs | $		$ 400,000
Proceeds From Issuance of Common Stock and Warrants | $		$ 3,700,000			$ 3,356,000	$ 0
Common Stock Units [Member] | Underwriting Agreement [Member]
Stock Issued During Period, Shares, New Issues (in shares)			805,900
Pre-Funded Units [Member] | Underwriting Agreement [Member]
Stock Issued During Period, Shares, New Issues (in shares)			2,773,000
Related Party Notes [Member]
Debt Instrument, Face Amount | $								$ 1.5
Debt Instrument, Interest Rate, Stated Percentage							12.00%	8.00%
Reverse Stock Split [Member]
Stockholders' Equity Note, Stock Split, Conversion Ratio				10