24 April 1996 Real-time immunoassays using fiber optic long-period grating sensors
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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.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Tuan A. Tran, Tuan A. Tran, Vikram Bhatia, Vikram Bhatia, Tiffanie D'Alberto, Tiffanie D'Alberto, Kent A. Murphy, Kent A. Murphy, Richard O. Claus, Richard O. Claus, } "Real-time immunoassays using fiber optic long-period grating sensors", Proc. SPIE 2676, Biomedical Sensing, Imaging, and Tracking Technologies I, (24 April 1996); doi: 10.1117/12.238795; https://doi.org/10.1117/12.238795

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