Note 8 - Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued expenses	$ 10	$ 127
Accrued salaries and employee benefits	652	368
Accrued director compensation	648	277
Accrued clinical trial costs	519	276
Grant liability	630	645
Customer deposits	102	112
Total	$ 2,561	$ 1,805