Note 4 - Balance Sheet Components - Accounts Receivable, Net of Allowance (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Accounts receivable	$ 700	$ 334
Royalty [Member]
Accounts receivable	468	334
Customer Service Contracts [Member]
Accounts receivable	$ 232	$ 0

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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