Note 9 - Patents and Trademarks, Net (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

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

	December 31,
	2019			2018
Purchased and licensed patent rights	$	566		$	566
Internally developed patents		1,686			1,686
Trademarks		148			148
Total		2,400			2,400
Accumulated amortization		(2,161	)		(2,078	)
Total intangible assets, net	$	239		$	322

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

December 31,	Aggregate Amortization Expense
2020	$	81
2021		56
2022		29
2023		20
2024		17
Thereafter		36
	$	239

Finite-lived Intangible Assets, Accumulated Amortization [Table Text Block]

	December 31,
	2019			2018
Purchased and licensed patent rights	$	(555	)	$	(548	)
Internally developed patents		(1,471	)		(1,400	)
Trademarks		(135	)		(130	)
Total	$	(2,161	)	$	(2,078	)

Finite-lived Intangible Assets, Weighted Average Amortization Periods [Table Text Block]

	December 31,
	2019		2018
Purchased and licensed patent rights		17		17
Internally developed patents		17		17
Trademarks		10		10