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Proceedings Paper

Intrinsic optical fiber sensor for sensing organophosphate nerve agent using the modified cladding approach
Author(s): Lalitkumar Bansal; Mahmoud El-Sherif
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Paper Abstract

The concept of modified cladding based sensors represents the largest class of intrinsic fiber optic chemical sensors. In this design, the passive cladding of the optical fiber is replaced by an active coating, called modified cladding. The analyte in this case diffuses into the coating and induces changes in the absorbance, fluorescence, or some other spectroscopic property of the modified cladding, the coating acts as a chemo-chromic transducer and sensing takes place by intensity modulation. This design i.e. of the coating based sensors, has found enormous applicability in the realm of chemical and biochemical sensing which also includes environmental monitoring and detection of chemical warfare agents. In this paper, the development of an intrinsic fiber optic sensor for detection of organophosphate dimethyl-methyl phoshopnate (DMMP) is presented. DMMP is a chemical precursor to the nerve agent sarin. The chemo-chromic transducer material used as a modified coating on the fiber core is NDSA (Naphthalene disulphonic acid) doped polypyrrole. This coating material shows conductivity and absorbance change when exposed to DMMP. The fabrication of the sensor device is a three step process which involves (a) etching a small section of the optical fiber to expose the core, (b) coating the etched section of the optical fiber with the polymer, (c) integration of sensor components and testing. Thin film characterization is done using the UV-Vis spectrophotometer on in-situ coated films of polypyrrole on a glass substrate to check for absorbance change upon exposure to DMMP. The development procedure is presented next and encouraging results are discussed.

Paper Details

Date Published: 8 March 2004
PDF: 10 pages
Proc. SPIE 5269, Chemical and Biological Point Sensors for Homeland Defense, (8 March 2004); doi: 10.1117/12.514810
Show Author Affiliations
Lalitkumar Bansal, Drexel Univ. (United States)
Mahmoud El-Sherif, Drexel Univ. (United States)
Photonics, Inc. (United States)

Published in SPIE Proceedings Vol. 5269:
Chemical and Biological Point Sensors for Homeland Defense
Arthur J. Sedlacek; Richard Colton; Tuan Vo-Dinh, Editor(s)

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