Note 4 - Select Balance Sheet Details (Details Textual)	1 Months Ended		3 Months Ended		6 Months Ended	9 Months Ended		12 Months Ended
	May 31, 2021 USD ($) shares	May 31, 2020 USD ($) shares	Sep. 30, 2021 USD ($) shares	Sep. 30, 2020 USD ($)	Sep. 30, 2021 USD ($) shares	Sep. 30, 2021 USD ($) shares	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
Inventory, Gross, Total			$ 85,000		$ 85,000	$ 85,000		$ 40,000
Inventory, Work in Process, Gross			27,000		27,000	27,000		26,000
Inventory, Finished Goods, Gross, Total			58,000		58,000	58,000		14,000
Inventory, LIFO Reserve			3,000		3,000	3,000		3,000
Finite-Lived Patents, Gross			49,000		49,000	49,000		58,000
Finite-Lived Intangible Assets, Accumulated Amortization			610,000		610,000	610,000		601,000
Amortization of Intangible Assets, Total			3,000	$ 3,000		$ 9,000	$ 9,000
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life (Year)						4 years 29 days
Number of Reporting Units						1
Goodwill, Ending Balance			$ 3,416,000		$ 3,416,000	$ 3,416,000		3,416,000
Goodwill, Impairment Loss						$ 0
Goodwill and Intangible Asset Impairment, Total								$ 0
Other Assets [Member]
Deferred Offering Costs	$ 70,000
Lincoln Park [Member]
Sale of Stock, Number of Shares Issued in Transaction (in shares) | shares	1,000,000	2,500,000	0		1,000,000	1,000,000
Deferred Offering Costs	$ 70,000	$ 400,000	$ 70,000		$ 70,000	$ 70,000
Amortization of Other Deferred Charges						364,000
Identity Management [Member]
Goodwill, Ending Balance			$ (13,748,000)		$ (13,748,000)	$ (13,748,000)