Note 13 - 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
Statutory federal income tax benefit	$	(3,530,000	)	$	(2,118,000	)
Intangible assets		69,000			673,000
Change in valuation allowance		197,000			(681,000	)
Expiration of net operating losses		1,558,000			1,187,000
Disallowed financing costs		1,619,000			1,119,000
State and local taxes		(18,000	)		(205,000	)
Other		105,000			25,000
Total income tax expense	$	--		$	--

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

	Year Ended December 31,
	2020			2019
Deferred tax assets:
Net operating loss carryforwards	$	27,312,000		$	26,758,000
Income tax credit carryforwards		2,852,000			2,757,000
Stock compensation		369,000			384,000
Lease obligation		160,000			185,000
Deferred revenue		340,000			419,000
Other		528,000			943,000
Total deferred tax assets		31,561,000			31,446,000
Deferred tax liabilities
Depreciation and amortization		(352,000	)		(408,000	)
Lease asset		(153,000	)		(180,000	)
Total deferred tax liabilities		(505,000	)		(588,000	)
Valuation allowance		(31,056,000	)		(30,858,000	)
Net deferred taxes	$	--		$	--