Note 16 - 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
Statutory federal income tax benefit	$	(2,495,000	)	$	(3,530,000	)
Intangible assets		--			69,000
PPP loan forgiveness		(137,000	)		--
Incentive stock options		257,000			56,000
Change in valuation allowance		(72,000	)		197,000
Expiration of net operating losses		1,242,000			1,558,000
Disallowed financing costs		1,282,000			1,619,000
State and local taxes		(195,000	)		(31,000	)
Foreign rate differential		26,000			13,000
Other		92,000			49,000
Total income tax expense	$	--		$	--

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

	Year Ended December 31,
	2021			2020
Deferred tax assets:
Net operating loss carryforwards	$	27,088,000		$	27,312,000
Income tax credit carryforwards		2,797,000			2,852,000
Stock compensation		437,000			369,000
Lease obligation		127,000			160,000
Deferred revenue		313,000			366,000
Inventory reserve		449,000			234,000
Other		213,000			268,000
Total deferred tax assets		31,424,000			31,561,000
Deferred tax liabilities
Depreciation and amortization		(320,000	)		(352,000	)
Lease asset		(120,000	)		(153,000	)
Total deferred tax liabilities		(440,000	)		(505,000	)
Valuation allowance		(30,984,000	)		(31,056,000	)
Net deferred taxes	$	--		$	--