title: Interferometric fiber-optic sensor embedded in a spark plug for in-cylinder pressure measurement in engines.
abstract: Pressure sensing in an internal combustion engine with an intrinsic fiber Fabry-Perot interferometer (FFPI) integrated with a spark plug is demonstrated for the first time. The spark plug was used for the ignition of the cylinder in which it was mounted. The FFPI element, protected with a copper/gold coating, was embedded in a groove in the spark-plug housing. Gas pressure inthe engine induced longitudinal strain in this housing, which was also experienced by the fiber-optic sensing element. The sensor was monitored with a signal conditioning unit containing a chirped distributed-feedback laser. Pressure sensitivities as high as 0.00339 radians round-trip phase shift per pounds per square inch of pressure were observed. Measured pressure versus time traces showed good agreement with those from a piezoelectric reference sensor mounted in the same engine cylinder.
authors.affiliation: Department of Electrical Engineering, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: Taehan
authors.initials: T
authors.lastname: Bae
authors.forename: Robert A
authors.initials: RA
authors.lastname: Atkins
authors.forename: Henry F
authors.initials: HF
authors.lastname: Taylor
authors.forename: William N
authors.initials: WN
authors.lastname: Gibler