Note 11 - Stockholders' Equity - Stock-based Compensation (Details) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Stock-based compensation	$ 880,000	$ 614,000
Cost of Sales [Member]
Stock-based compensation	9,000	3,000
Selling and Marketing Expense [Member]
Stock-based compensation	176,000	185,000
Research and Development Expense [Member]
Stock-based compensation	114,000	98,000
General and Administrative Expense [Member]
Stock-based compensation	$ 581,000	$ 328,000

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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