Note 7 - Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Accrued expenses	$ 240	$ 87
Accrued salaries and employee benefits	861	961
Accrued clinical trial costs	334	452
Grant liability	590	615
Customer deposits	96	90
Total	$ 2,121	$ 2,205