Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Net sales	$ 23,283	$ 22,506
Cost of goods sold	14,347	14,149
Gross profit	8,936	8,357
Operating expenses:
Selling expenses	2,492	2,459
General and administrative	3,529	3,828
Research and development	2,452	2,741
Total operating expenses	8,473	9,028
Earnings (loss) from operations	463	(671)
Other expense:
Interest expense, net	(723)	(412)
Change in derivative liability	(142)	(83)
Total other expense	(865)	(495)
Loss before income taxes	(402)	(1,166)
Provision (benefit) for income taxes	(18)	29
Net loss	$ (384)	$ (1,195)
Net loss per share, basic and diluted	$ (0.05)	$ (0.16)
Weighted average shares outstanding, basic and diluted	8,189	7,413
Statements of Comprehensive Income (Loss)
Net loss	$ (384)	$ (1,195)
Changes in accumulated unrealized pension losses, net of taxes	424	(110)
Comprehensive income (loss)	$ 40	$ (1,305)