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Proceedings Paper

Fluorescence-lifetime-based sensors using inhomogeneous waveguiding
Author(s): Sonja Draxler; Dietmar Kieslinger; Karolina Trznadel; Max E. Lippitsch
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Paper Abstract

Most intrinsic fiberoptic sensors are based on the evanescent-wave scheme, where the evanescent field of modes guided in a fiber reaches out into a chemically sensitive coating. In the commonly used multimode waveguides, the evanescent field contains only a small part of the total energy, however, thus making evanescent-wave sensors rather insensitive. Combining a transparent substrate and a transparent sensing layer of rather similar refractive index into a common waveguiding structure produces an inhomogeneous waveguide, where a large portion of the total energy transverses the sensing layer. This yields much superior sensor performance. The transmission through a waveguide is subject to various disturbing influences. Thus it is advantageous to combine the inhomogeneous waveguiding approach with a measuring scheme that is not prone to those disturbances. Such a scheme is available with fluorescence lifetime-based sensors. The fluorescence lifetime of an indicator incorporated into the sensing layer is changed by the presence of the respective analyte. This lifetime is independent of the transmission through the waveguide. Thus inhomogeneous waveguiding together with fluorescence lifetime measurement paves the way for optical chemical sensors with high analyte sensitivity and immunity to external disturbances.

Paper Details

Date Published: 10 December 1996
PDF: 7 pages
Proc. SPIE 2836, Chemical, Biochemical, and Environmental Fiber Sensors VIII, (10 December 1996); doi: 10.1117/12.260612
Show Author Affiliations
Sonja Draxler, Karl-Franzens-Univ. Graz (Austria)
Dietmar Kieslinger, Karl-Franzens-Univ. Graz (Austria)
Karolina Trznadel, Karl-Franzens-Univ. Graz (Austria)
Max E. Lippitsch, Karl-Franzens-Univ. Graz (Austria)


Published in SPIE Proceedings Vol. 2836:
Chemical, Biochemical, and Environmental Fiber Sensors VIII
Robert A. Lieberman, Editor(s)

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