Note 13 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

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

	Years ended December 31,
	2019			2018			2017
Tax at federal statutory rate	$	(3,089	)	$	(2,937	)	$	(4,185	)
State, net of federal benefit		(414	)		(455	)		(1,238	)
Research and development credit		(225	)		(236	)		(135	)
Stock-based compensation		446			440			344
Change in Federal Tax Rate		-			-			8,172
Other		5			22			7
Change in valuation allowance		3,277			3,166			(2,965	)
Total provision for income taxes	$	—		$	-		$	-

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

	Years ended December 31,
	2019			2018
Accrued compensation	$	148		$	84
Inventory adjustments		297			276
Depreciation and amortization		98			113
Stock-based compensation		744			648
Net operating loss and tax credit carryforwards		23,809			20,698
Other		11			12
Gross Deferred Tax Asset		25,107			21,831
Valuation Allowance		(25,107	)		(21,831	)
Net deferred tax asset	$	-		$	-

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

	Years ended December 31,
	2019		2018
Balance, beginning of year	$	891	$	725
Additions based on tax positions related to the current year		155		166
Balance, end of year	$	1,046	$	891