CONSOLIDATED STATEMENTS OF OPERATIONS (in thousands, except per share amounts) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
Net sales	$ 5,834	$ 7,204	$ 11,892	$ 14,834
Cost of goods sold	2,250	2,955	4,623	6,169
Gross margin	3,584	4,249	7,269	8,665
Operating expenses:
Research and development	1,680	1,845	3,361	3,724
Selling, general and administrative	1,829	2,158	3,803	4,351
Total operating expenses	3,509	4,003	7,164	8,075
Operating income	75	246	105	590
Non-operating income:
Interest income	10	9	22	16
Gain on sale of assets	0	4	60	4
Foreign currency transaction gain (loss)	69	269	(36)	93
Total non-operating income	79	282	46	113
Income before income taxes	154	528	151	703
Income tax (expense) benefit	(27)	(42)	2	(87)
Net income	$ 127	$ 486	$ 153	$ 616
Basic earnings per share	$ 0.02	$ 0.06	$ 0.02	$ 0.07
Diluted earnings per share	$ 0.02	$ 0.06	$ 0.02	$ 0.07
Weighted-average basic shares	8,257	8,356	8,280	8,321
Weighted-average diluted shares	8,332	8,500	8,375	8,521