Note 7 - Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accrued expenses	$ 105	$ 10
Accrued salaries and employee benefits	843	652
Accrued director compensation		648
Accrued clinical trial costs	578	519
Grant liability	620	630
Customer deposits	90	102
Total	$ 2,236	$ 2,561