Note 4 - Equipment and Leasehold Improvements, Net - Summary of Property, Plant, and Equipment (Details) - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Property, Plant, and Equipment, Gross	$ 7,926,000	$ 7,995,000
Less accumulated depreciation	(5,898,000)	(5,433,000)
Total equipment and leasehold improvements, net	2,028,000	2,562,000
Machinery and Equipment [Member]
Property, Plant, and Equipment, Gross	$ 6,107,000	6,136,000
Machinery and Equipment [Member] \| Minimum [Member]
Estimated Useful Life (Year)	2 years 182 days
Machinery and Equipment [Member] \| Maximum [Member]
Estimated Useful Life (Year)	10 years
Computer and Software [Member]
Property, Plant, and Equipment, Gross	$ 631,000	664,000
Computer and Software [Member] \| Minimum [Member]
Estimated Useful Life (Year)	2 years
Computer and Software [Member] \| Maximum [Member]
Estimated Useful Life (Year)	5 years
Office Equipment [Member]
Property, Plant, and Equipment, Gross	$ 256,000	264,000
Office Equipment [Member] \| Minimum [Member]
Estimated Useful Life (Year)	5 years
Office Equipment [Member] \| Maximum [Member]
Estimated Useful Life (Year)	10 years
Leasehold Improvements [Member]
Property, Plant, and Equipment, Gross	$ 932,000	$ 931,000
Leasehold Improvements, Estimated Useful Life	Shorter of 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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Describes the periods of time over which an entity anticipates to receive utility from its property, plant and equipment (that is, the periods of time over which an entity allocates the initial cost of its property, plant and equipment).

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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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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