CONSOLIDATED STATEMENTS OF OPERATIONS (in thousands, except per share amounts) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Net sales	$ 3,808	$ 6,533	$ 15,700	$ 21,367
Cost of goods sold	1,806	2,415	6,430	8,584
Gross margin	2,002	4,118	9,270	12,783
Operating expenses:
Research and development	1,507	1,826	4,868	5,550
Selling, general and administrative	1,535	1,888	5,338	6,239
Total operating expenses	3,042	3,714	10,206	11,789
Operating income (loss)	(1,040)	404	(936)	994
Non-operating income:
Interest income	25	10	47	26
Gain on sale of assets	0	0	60	4
Foreign currency transaction gain (loss)	226	108	190	201
Total non-operating income	251	118	297	231
Income (loss) before income taxes	(789)	522	(639)	1,225
Income tax (expense) benefit	(55)	(180)	(52)	(267)
Net income (loss)	$ (844)	$ 342	$ (691)	$ 958
Basic earnings (loss) per share	$ (0.10)	$ 0.04	$ (0.08)	$ 0.11
Diluted earnings (loss) per share	$ (0.10)	$ 0.04	$ (0.08)	$ 0.11
Weighted-average basic shares	8,217	8,439	8,259	8,361
Weighted-average diluted shares	8,242	8,507	8,259	8,516