Note 11 - Stockholders' Equity (Details Textual) - USD ($)					12 Months Ended
	Nov. 22, 2023	Mar. 15, 2023	Oct. 28, 2022	Dec. 29, 2017	Dec. 31, 2023	Dec. 31, 2022	Feb. 03, 2023	Dec. 15, 2022	Mar. 31, 2022	Feb. 03, 2022	Jan. 13, 2022	Dec. 31, 2021	May 31, 2019	Jun. 22, 2018	May 31, 2017
Common Stock, Par or Stated Value Per Share		$ 0.001			$ 0.001	$ 0.001
Stock Issued During Period, Shares, New Issues (in shares)		125,000
Proceeds from Issuance of Common Stock, Net					$ 2,857,000	$ 4,583,000
Payments of Stock Issuance Costs		$ 360,000	$ 506,000
Class of Warrant or Right, Outstanding (in shares)					1,238,869	340,689						14,518
Proceeds from Issuance or Sale of Equity		$ 2,640,000	$ 2,055,000
Proceeds from Warrant Exercises					$ 421,000	$ 3,000
Shares Issued, Price Per Share			$ 6.3
Proceeds from Issuance or Sale of Equity, Net			$ 1,549,000
Share-Based Payment Arrangement, Expense					$ 39,000	$ 267,000
Amended 2016 Plan [Member
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized								66,667			26,667		8,723	2,945	1,334
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant					60,479
Equity Incentive Plan 2017 [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized				1,000,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant					40,000
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross				280,000
Units [Member]
Stock Issued During Period, Units, New Issues			326,171
Units Issued, Common Shares Per Unit			1
Units Issued, Warrants Per Unit			1
Pre-funded Units [Member]
Stock Issued During Period, Units, New Issues			64,286
Pre-funded Warrant [Member]
Class of Warrant or Right, Outstanding (in shares)		946,429
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 2.8
Warrants Exercised (in shares)					946,429
Units Issued, Warrants Per Unit			1
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right			1
Common Warrants [Member]
Class of Warrant or Right, Outstanding (in shares)		1,071,429
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 2.65
Warrants and Rights Outstanding, Term (Year)		5 years 6 months
Units Issued, Warrants Per Unit			1
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right			1
Warrants Issued in Connection with Underwritten Public Offering [Member]
Fair Value Adjustment of Warrants		$ 50,000
The Units Warrants [Member]
Units Issued, Common Shares Per Unit			1
Offering Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)			$ 6.3
Warrants and Rights Outstanding, Term (Year)			5 years
Warrants and Rights Outstanding, Warrants Exercised						64,286
At The Market Offering Agreement [Member]
Common Stock, Par or Stated Value Per Share	$ 0.001
Maximum Offering Price for Issuance of Common Stock	$ 1,288,000								$ 18,573,000
Stock Issued During Period, Shares, New Issues (in shares)	481,382					196,843
Proceeds from Issuance of Common Stock	$ 429,000					$ 3,293,000
Shares Issued, Average Price Per Share (in dollars per share)	$ 0.89					$ 16.73
Proceeds from Issuance of Common Stock, Net	$ 216,000					$ 3,037,000
Payments of Stock Issuance Costs	$ 213,000					$ 256,000
Additional Common Stock, Shares Authorized							$ 4,275,000
At The Market Offering Agreement [Member] | Minimum [Member]
Maximum Offering Price for Issuance of Common Stock										$ 15,280,000
At The Market Offering Agreement [Member] | Maximum [Member]
Maximum Offering Price for Issuance of Common Stock										$ 19,555,000
Warrant Amendment Agreement [Member]
Stock Issued During Period, Shares, New Issues (in shares)		158,731
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 6.3			$ 2.65
Warrants Exercised (in shares)					158,731
Proceeds from Warrant Exercises					$ 421,000