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Proceedings Paper

Real-time immunoassays using fiber optic long-period grating sensors
Author(s): Tuan A. Tran; Vikram Bhatia; Tiffanie D'Alberto; Kent A. Murphy; Richard O. Claus
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Paper Abstract

Photoinduced long-period gratings (LPG) in optical fibers offer a completely new approach to the fabrication of highly sensitive evanescent wave biosensors. In contrast to other types of evanescent wave sensors where a surface plasmon must be carefully constructed from a waveguide substrate that must be polished and deposited with a thin metallic film of precise thickness via a sputtering process, the proposed technique simply relies on the formation of gratings within a communication grade germanium-doped optical fiber. Using an amplitude mask that is optimized for operation at 244 nm, an incoming collimated UV beam forms a spatially periodic optical intensity pattern along the axis of the fiber. Given sufficient exposure time on the order of seconds, a refractive index grating is induced within the core of the fiber. In this method, the LPG is used to detect and monitor in real-time the interaction of a specific antigen to the immobilized antibody on the silica fiber. When the density of the bound protein changes (i.e., when the antigen binds to the antibody), the associated refractive index of the bound film will also change. If a broadband light source is injected into the optical fiber, the output spectrum of the LPG sensor will shift in response to the refractive index changes.

Paper Details

Date Published: 24 April 1996
PDF: 6 pages
Proc. SPIE 2676, Biomedical Sensing, Imaging, and Tracking Technologies I, (24 April 1996); doi: 10.1117/12.238795
Show Author Affiliations
Tuan A. Tran, Fiber and Sensor Technologies, Inc. (United States)
Vikram Bhatia, Virginia Polytechnic Institute and State Univ. (United States)
Tiffanie D'Alberto, Virginia Polytechnic Institute and State Univ. (United States)
Kent A. Murphy, Fiber and Sensor Technologies, Inc. (United States)
Richard O. Claus, Virginia Polytechnic Institute and State Univ. (United States)


Published in SPIE Proceedings Vol. 2676:
Biomedical Sensing, Imaging, and Tracking Technologies I
Robert A. Lieberman; Halina Podbielska; Tuan Vo-Dinh, Editor(s)

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