Note 5 - Equipment and Leasehold Improvements, Net - Summary of Property, Plant, and Equipment (Details) - USD ($)	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Property, Plant, and Equipment, Gross	$ 8,089,000	$ 7,823,000
Less accumulated depreciation	(6,828,000)	(6,399,000)
Total equipment and leasehold improvements, net	1,261,000	1,424,000
Machinery and Equipment [Member]
Property, Plant, and Equipment, Gross	$ 6,270,000	6,004,000
Machinery and Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	2 years 6 months
Machinery and Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	10 years
Computer and Software [Member]
Property, Plant, and Equipment, Gross	$ 631,000	631,000
Computer and Software [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	2 years
Computer and Software [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years
Office Equipment [Member]
Property, Plant, and Equipment, Gross	$ 256,000	256,000
Office Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	5 years
Office Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	10 years
Leasehold Improvements [Member]
Property, Plant, and Equipment, Gross	$ 932,000	$ 932,000
Leasehold Improvements, Estimated Useful Life	5 years or remaining lease term

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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