Intangible Assets

3 Months Ended

Mar. 31, 2022

Intangible Assets, Net (Excluding Goodwill) [Abstract]

Intangible Assets

10. INTANGIBLE ASSETS: 

Intangible assets consist of the following: 

	March 31, 2022							December 31, 2021
(In thousands)	Gross Carrying Amount		Accumulated Amortization			Net		Gross Carrying Amount		Accumulated Amortization			Net
Patents	$	2,001	$	(1,665	)	$	336	$	1,972	$	(1,614	)	$	358
Software	206		(206		)	—		206		(206		)	—
Marketing assets and customer relationships	86		(71		)	15		86		(69		)	17
Total intangible assets	$	2,293	$	(1,942	)	$	351	$	2,264	$	(1,889	)	$	375

Amortization expense in the three months ended March 31, 2022 and March 31, 2021 was as follows:   

	Three Months Ended March 31,
(In thousands)	2022		2021
Patents	$	50	$	43
Software		—		6
Marketing assets and customer relationships		2		2
Total amortization expense	$	52	$	51

Estimated aggregate amortization expense based on current intangible assets for the next four years is expected to be as follows: $146,000 for the remainder of 2022; $150,000 in 2023; $54,000 in 2024; and $1,000 in 2025.