Importance

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Abstract

A pressure sensor comprises a chamber formed from two members micromachined in silicon or a similar substance. The members define a chamber with at least one pressure sensitive membrane and an optic fiber extending through the chamber parallel to the membrane. The membrane may have an optical grating formed thereon which may be coated with a surface plasmon supporting substance. Light is injected into the fiber with a wavelength that couples with the grating on the membrane, either in a Bragg relationship or in coupling to a surface plasmon. The coupling, and thus the light lost from the fiber, varies with separation between the membrane and fiber and thus with the pressure outside the chamber. The members also include a thicker wall which is not pressure sensitive but which couples with an identifiably distinct portion of the light in the optic fiber to provide a temperature compensated reference. The pressure sensor can be made very small and rugged for combustion chamber pressure sensing in an engine and for other uses where very small pressure sensors are required.

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First Claim