Note 3 - Balance Sheet Details - Summary of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Disclosure Text Block [Abstract]
Prepaid insurance	$ 1,818	$ 1,408
Other receivables	20	150
Prepaid subscriptions and fees	212	215
Prepaid software licenses	101	78
Deposits	21	26
Deferred equity issuance costs	263	0
Prepaid other	0	2
Prepaid expenses and other current assets	$ 2,435	$ 1,879