Note 3 - Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2018

Notes Tables

Schedule of Finite-Lived Intangible Assets [Table Text Block]

	December 31, 2018					December 31, 2017
	Gross Carrying		Accumulated			Gross Carrying		Accumulated
	Amount		Amortization			Amount		Amortization
Amortized intangible assets:
Patents	$	526,146	$	(149,740	)	$	476,177	$	(126,032	)
License		—		—			50,000		(48,959	)
	$	526,146	$	(149,740	)	$	526,177	$	(174,991	)

	2018		2017
Aggregate amortization expense:
For the years ended December 31	$	24,749	$	25,919

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

2019	$	25,000
2020		24,000
2021		24,000
2022		24,000
2023		23,000