Note 7 - Stockholders' Equity (Details Textual) - USD ($)				1 Months Ended	6 Months Ended
	Apr. 12, 2022	Mar. 29, 2021	Sep. 04, 2019	Apr. 30, 2022	Jun. 30, 2022	Jun. 30, 2021	Aug. 06, 2019
Proceeds from Issuance of Common Stock					$ 1,519,000	$ 2,001,000
Payments of Stock Issuance Costs					$ 165,000	$ 67,000
Underwriters [Member]
Stock Issued During Period, Shares, New Issues (in shares)			75,000
Purchase Agreement with Lincoln Park [Member]
Sale of Stock, Aggregate Value, Maximum		$ 20,000,000
Stock Issued During Period, Shares, New Issues (in shares)		373,832			0
Stock Issuable, Commitment Shares on Pro Rata Basis (in shares)		50,000
Shares Issued, Price Per Share (in dollars per share)		$ 5.35
Proceeds from Issuance of Common Stock		$ 2,000,000
Stock Issued During the Period, Shares, Commission Fees (in shares)		80,000
Stock Issued During the Period, Commitment Shares Issued on Pro Rata Basis (in shares)		5,000
Conditional Issuance, Maximum Number of Shares Allowed to be Purchased (in shares)		100,000
Stock Purchase Agreement Accelerated Purchase, Maximum, Percent of Shares Purchased on the Same Trading Day		300.00%
Stock Purchase Agreement Accelerated Purchase, Maximum, Percent of Total Common Shares Traded During Specified Period		30.00%
Maximum Number of Shares Allowed to be Issued Including Commitment Shares (in shares)		3,266,177
Percentage of Common Stock Outstanding		19.99%
Private Placement Unit [Member]
Number of Common Stock in Each Unit (in shares)							1
SalesAgreementWithCantorFitzgeraldCoCantorMember
Sale of Stock, Aggregate Value, Maximum	$ 10.5
Stock Issued During Period, Shares, New Issues (in shares)				575,000
Proceeds from Issuance of Common Stock				$ 1,500,000
Accrued Sales Commission, Current, Percentage	3.00%
Payments of Stock Issuance Costs				$ 232,000