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Proceedings Paper

Low-cost fiber optic hydrogen gas detector using guided-wave surface-plasmon resonance in chemochromic thin films
Author(s): David K. Benson; C. Ed Tracy; Gary A. Hishmeh; Paul E. Ciszek; Se-Hee Lee; D. P. Haberman
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Paper Abstract

Low-cost, hydrogen-gas-leak detectors are needed for many hydrogen applications, such as hydrogen-fueled vehicles where several detectors may be required in different locations on each vehicle. A fiber-optic leak detector could be inherently safer than conventional detectors, because it would remove all detector electronics from the vicinity of potential leaks. It would also provide freedom from electromagnetic interference, a serious problem in fuel- cell-powered electric vehicles. This paper describes the design of a fiber-optic, surface-plasmon-resonance hydrogen detector, and efforts to make it more sensitive, selective, and durable. Chemochromic materials, such as tungsten oxide and certain Lanthanide hydrides, can reversibly react with hydrogen in air while exhibiting significant changes in their optical properties. Thin films of these materials applied to a sensor at the nd of an optical fiber have been used to detect low concentrations of hydrogen gas in air. The coatings include a thin silver layer in which the surface plasmon is generated, a thin film of the chemochromic materials, and a catalytic layer of palladium that facilitates the reaction with hydrogen. The film thickness is chosen to produce a guided-surface plasmon wave along the interface between the silver and the chemichromic material. A dichroic beam-splitter separates the reflected spectrum into a portion near the resonance and a portion away from the resonance, and directs these two portions to two separate photodiodes. The electronic ratio of these two signals cancels most of the fiber transmission noise and provides a stable hydrogen signal.

Paper Details

Date Published: 22 January 1999
PDF: 18 pages
Proc. SPIE 3535, Advanced Sensors and Monitors for Process Industries and the Environment, (22 January 1999); doi: 10.1117/12.337465
Show Author Affiliations
David K. Benson, National Renewable Energy Lab. (United States)
C. Ed Tracy, National Renewable Energy Lab. (United States)
Gary A. Hishmeh, DCH Technologies Inc. (United States)
Paul E. Ciszek, Evergreen Solar (United States)
Se-Hee Lee, National Renewable Energy Lab. (United States)
D. P. Haberman, DCH Technologies Inc. (United States)

Published in SPIE Proceedings Vol. 3535:
Advanced Sensors and Monitors for Process Industries and the Environment
Wim A. de Groot, Editor(s)

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