Note 9 - Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Deferred income tax assets:
Allowance for doubtful accounts	$ 5,293	$ 5,060
Inventory capitalization	7,107	6,197
Depreciation and amortization
Research & development tax credits	588,096	413,680
Compensation costs	202,287	356,983
Vacation accrual	142,230	167,644
Interest expense carryforward	144,340	66,149
Net operating loss carryforward	1,798,315	832,565
Other items	52,232	16,446
Total deferred tax asset	2,939,900	1,864,724
Deferred incomes tax liability:
Property and equipment - tax over book depreciation	(442,486)	(439,310)
Less valuation allowance	(2,497,414)
Net long-term deferred tax asset		$ 1,425,414