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Proceedings Paper

Modified ZSM-5 zeolite film-integrated fiber optic sensors for ammonia detection
Author(s): Xiling Tang; Zhong Tang; Seok-Jhin Kim; Junhang Dong
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Paper Abstract

This paper reports the development of surface modified ZSM-5 zeolite thin-film coated long-period fiber grating (LPFG) sensors for in situ detection of ammonia (NH3). The sensor was fabricated by growing MFI-type zeolite thin film (i.e. ZSM-5 with Si/Al ratio of 15) on the optical fiber grating by in situ hydrothermal crystallization. The sensor measures ammonia concentration by monitoring the molecular adsorption-induced shift of LPFG resonant wavelength (λR) in near infrared (IR) region. Upon loading the analyte (NH3) molecules, the refractive index of the zeolite film changes in the close vicinity of the fiber index where the LPFG has a large response to achieve high sensitivity. High sensitivity of this sensor also comes from the ability of the nanoporous zeolite to effectively concentrate the target molecules by selective adsorption. The sensor was capable of sensitive detection of ammonia at lower ppm level. The zeolite's internal surface was modified by ion exchange with NH4+ followed by thermal treatments to enhance the surface acidity. The acidic ZSM-5 (i.e. H-ZSM-5) film exhibited higher sensitivity and improved selectivity for NH3.

Paper Details

Date Published: 30 April 2009
PDF: 8 pages
Proc. SPIE 7312, Advanced Environmental, Chemical, and Biological Sensing Technologies VI, 73120C (30 April 2009); doi: 10.1117/12.817887
Show Author Affiliations
Xiling Tang, Univ. of Cincinnati (United States)
Zhong Tang, Univ. of Cincinnati (United States)
Seok-Jhin Kim, Univ. of Cincinnati (United States)
Junhang Dong, Univ. of Cincinnati (United States)

Published in SPIE Proceedings Vol. 7312:
Advanced Environmental, Chemical, and Biological Sensing Technologies VI
Tuan Vo-Dinh; Robert A. Lieberman; Günter Gauglitz, Editor(s)

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