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Note 4 - Balance Sheet Components (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Accounts Receivable, after Allowance for Credit Loss, Current, Total	$ 107,000		$ 107,000		$ 334,000
Accounts Receivable, Allowance for Credit Loss, Current	0		0		0
Depreciation, Total	120,000	$ 25,000	195,000	$ 44,000
Impairment of Property and Equipment			0	0
Amortization of Intangible Assets, Total	433,000	$ 433,000	$ 866,000	$ 866,000
Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Remaining Life (Year)			8 years 4 months 24 days
Intellectual Property [Member]
Finite-Lived Intangible Asset, Useful Life (Year)			20 years
Finite-Lived Intangible Asset, Remaining Life (Year)			6 years 6 months
Minimum [Member] \| Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Useful Life (Year)			1 year 3 months 18 days
Maximum [Member] \| Developed Technology Rights [Member]
Finite-Lived Intangible Asset, Useful Life (Year)			11 years 9 months
Royalty [Member]
Accounts Receivable, after Allowance for Credit Loss, Current, Total	$ 107,000		$ 107,000		$ 334,000