Note 14 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2021

Notes Tables

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

	Year Ended December 31,
	2021			2020
Income tax benefit at statutory rate		(21	)%		(21	)%
State income taxes, net of federal benefit		(3	)%		(3	)%
Change in valuation allowance		21	%		20	%
Other		3	%		4	%
Effective tax rate		0	%		0	%

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

	Year Ended December 31,
	2021			2020
Deferred tax assets:
Net operating loss carryforwards	$	25,092		$	20,891
Capitalized start up costs		2,511			2,866
Research and development credits		781			631
Accruals and reserves		1,537			773
Fixed assets and depreciation		124			291
Total deferred tax assets		30,045			25,452
Deferred tax liabilities:
Valuation allowance		(30,045	)		(25,452	)
Net deferred tax assets	$	-		$	-

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

	Year Ended December 31,
	2021			2020
Balance at the beginning of the year	$	245		$	223
Additions (deletions) based upon tax positions related to the current year		(14	)		22
Balance at the end of the year	$	231		$	245