Note 4 - Intangible Assets and Goodwill - Summary of Intangible Assets (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Gross Carrying Amount	$ 1,310,000	$ 1,317,000
Accumulated Amortization	1,095,000	993,000
Net	215,000	324,000
Impairment
Gross Carrying Amount	2,453,000	2,460,000
Impairment
Net	1,358,000	1,467,000	$ 1,591,000
In Process Techonology [Member]
Gross Carrying Amount	1,143,000	1,143,000
Impairment
Net	$ 1,143,000	$ 1,143,000
Trade Names [Member]
Weighted Average Amortization Period (Year)	3 years	3 years
Gross Carrying Amount	$ 52,000	$ 53,000
Accumulated Amortization	52,000	45,000
Net		$ 8,000
Developed Technology Rights [Member]
Weighted Average Amortization Period (Year)	10 years	10 years
Gross Carrying Amount	$ 318,000	$ 318,000
Accumulated Amortization	111,000	79,000
Net	$ 207,000	$ 239,000
Licensing Agreements [Member]
Weighted Average Amortization Period (Year)	7 years	7 years
Gross Carrying Amount	$ 432,000	$ 437,000
Accumulated Amortization	424,000	367,000
Net	$ 8,000	$ 70,000
Device Registration [Member]
Weighted Average Amortization Period (Year)	7 years	7 years
Gross Carrying Amount	$ 66,000	$ 66,000
Accumulated Amortization	66,000	66,000
Net
Impairment
Customer Relationships [Member]
Weighted Average Amortization Period (Year)	3 years	3 years
Gross Carrying Amount	$ 442,000	$ 443,000
Accumulated Amortization	442,000	436,000
Net		7,000
Impairment