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Proceedings Paper

Optical immunoassay systems based upon evanescent wave interactions
Author(s): Douglas A. Christensen; James N. Herron
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Paper Abstract

Immunoassays based upon evanescent wave interactions are finding increased biosensing application. In these devices, the evanescent tail associated with total internal reflection of an incident beam at the substrate/solution interface provides sensitivity for surface-bound protein over bulk molecules, allowing homogeneous assays and real-time measurement of binding dynamics. Among such systems are surface plasmon resonance sensors and a resonant mirror device. Several research groups are also developing fluorescent fiberoptic or planar waveguide sensors for biomedical applications. We describe a second-generation planar waveguide fluoroimmunoassay system being developed in our laboratory which uses a molded polystyrene sensor. The 633-nm beam from a laser diode is focused into the 500 micrometer- thick planar waveguide by an integral lens. Antibodies to the desired analyte (hCG) are immobilized on the waveguide surface and fluorescence from bound analyte/tracer antibodies in a sandwich format is imaged onto the detector. The geometry of the waveguide allows several zones to be detected, providing the capability for on-sensor calibration. This sensor has shown picomolar sensitivity for the detection of hCG.

Paper Details

Date Published: 1 April 1996
PDF: 10 pages
Proc. SPIE 2680, Ultrasensitive Biochemical Diagnostics, (1 April 1996); doi: 10.1117/12.237631
Show Author Affiliations
Douglas A. Christensen, Univ. of Utah (United States)
James N. Herron, Univ. of Utah (United States)

Published in SPIE Proceedings Vol. 2680:
Ultrasensitive Biochemical Diagnostics
Gerald E. Cohn; Steven A. Soper; C. H. Winston Chen, Editor(s)

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