Note 14 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Notes Tables

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Year Ended
	December 31,
	2020			2019
Income tax benefit at statutory rate		(21	)%		(21	)%
State income taxes, net of federal benefit		(3	)%		(4	)%
Change in valuation allowance		20	%		(39	)%
Debt restructuring		0	%		6	%
Limitation on net operating loss and credit carryovers		0	%		56	%
Other		4	%		2	%
Effective tax rate		0	%		0	%

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	December 31,
	2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	20,891		$	16,688
Capitalized start up costs		2,866			3,225
Research and development credits		631			527
Accruals and reserves		773			532
Fixed assets and depreciation		291			128
Total deferred tax assets		25,452			21,100
Deferred tax liabilities:
Valuation allowance		(25,452	)		(21,100	)
Net deferred tax assets	$	-		$	-

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

	Year Ended
	December 31,
	2020		2019
Balance at the beginning of the year	$	223	$	450
Additions (deletions) based upon tax positions related to the current year		22		(227	)
Balance at the end of the year	$	245	$	223