10. INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2021

Goodwill and Intangible Assets Disclosure [Abstract]

10. INTANGIBLE ASSETS

10. INTANGIBLE ASSETS

Our intangible assets consist exclusively of technology-based purchased patents. The gross book value of our intangible assets was $951,000 in the years ended December 31, 2021 and 2020, respectively. Amortization expense was $49,000 in 2021, $57,000 in 2020 and $105,000 in 2019. In 2019, we recorded an impairment amounting to $160,000 on 52 patents that we elected not to renew, and one patent abandoned in prosecution.

The following table outlines our estimated future amortization expense related to intangible assets held at December 31, 2021 (in thousands):

Years Ended December 31,		Amount
2022	$	40
2023		32
2024		22
2025		14
2026		7
Thereafter		-
Total	$	115