Condensed Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenue:
Total Revenue	$ 4,225	$ 3,893	$ 7,597	$ 6,903
Cost of revenue:
Total Cost of revenue	1,199	701	1,976	1,148
Gross profit	3,026	3,192	5,621	5,755
Operating expenses:
Selling, general and administrative	1,682	1,765	3,347	3,526
Research and development	697	916	1,317	1,735
Restructuring charges	0	0	2	0
Total Operating expenses	2,379	2,681	4,666	5,261
Operating income from operations	647	511	955	494
Income from operations before income taxes	647	511	955	494
Income tax expense	0	0	0	0
Net income	$ 647	$ 511	$ 955	$ 494
Net income per share:
Basic (in dollars per share)	$ 0.12	$ 0.10	$ 0.18	$ 0.10
Diluted (in dollars per share)	$ 0.12	$ 0.10	$ 0.18	$ 0.10
Weighted average number of common shares outstanding:
Basic (in shares)	5,244	5,206	5,234	5,194
Diluted (in shares)	5,259	5,219	5,248	5,194
Product sales [Member]
Revenue:
Total Revenue	$ 2,020	$ 1,376	$ 3,641	$ 2,220
Cost of revenue:
Total Cost of revenue	1,108	609	1,793	964
Royalties [Member]
Revenue:
Total Revenue	2,205	2,517	3,956	4,683
Cost of revenue:
Total Cost of revenue	$ 91	$ 92	$ 183	$ 184