7. Intangible Assets

9 Months Ended

Sep. 30, 2015

Goodwill and Intangible Assets Disclosure [Abstract]

7. Intangible Assets

Intangible assets consisted of the following for the periods indicated (in thousands):

	September 30, 2015
	Gross Amount		Accumulated amortization			Intangible assets, net
Patents	$	5,298	$	(1,445	)	$	3,853
Trademarks		14		(9	)		5
Total intangible assets		5,312		(1,454	)		3,858

	December 31, 2014
	Gross Amount		Accumulated amortization			Intangible assets, net
Patents	$	4,968	$	(1,141	)	$	3,827
Trademarks		14		(8	)		6
Total intangible assets		4,982		(1,149	)		3,833

For the three months ended September 30, 2015 and 2014, amortization expense for intangible assets, included in general and administrative expenses on the income statement, was $104,000 and $94,000, respectively. For the nine months ended September 30, 2015 and 2014, amortization expense for intangible assets, included in general and administrative expenses on the income statement, was $305,000 and $258,000, respectively. The remaining weighted average amortization period for intangible assets is approximately 9 years.