Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue:
Total Revenue	$ 3,272	$ 3,750	$ 10,039	$ 10,296
Cost of revenue:
Total Cost of revenue	585	883	2,118	2,117
Gross profit	2,687	2,867	7,921	8,179
Operating expenses:
Selling, general and administrative	1,334	1,422	4,216	4,894
Research and development	644	804	1,681	2,548
Total Operating expenses	1,978	2,226	5,897	7,442
Income from operations	709	641	2,024	737
Other income, net	0	0	925	0
Income from operations before income taxes	709	641	2,949	737
Income tax expense (benefit)	96	(18)	453	39
Net income	$ 613	$ 659	$ 2,496	$ 698
Net income per share:
Basic (in dollars per share)	$ 0.11	$ 0.12	$ 0.47	$ 0.13
Diluted (in dollars per share)	$ 0.11	$ 0.12	$ 0.47	$ 0.13
Weighted average number of common shares outstanding:
Basic (in shares)	5,349	5,306	5,338	5,290
Diluted (in shares)	5,361	5,311	5,351	5,306
Product sales [Member]
Revenue:
Total Revenue	$ 805	$ 1,538	$ 3,273	$ 3,760
Cost of revenue:
Total Cost of revenue	480	791	1,823	1,842
Royalties [Member]
Revenue:
Total Revenue	2,467	2,212	6,766	6,536
Cost of revenue:
Total Cost of revenue	$ 105	$ 92	$ 295	$ 275