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Proceedings Paper

Resonant grating biosensor platform design and fabrication
Author(s): Valerie Brioude; Rachida Saoudi; Daniele Blanc; Stephanie Reynaud; Svetlen Tonchev; Nikolai M. Lyndin; James Molloy
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Paper Abstract

Grating coupled evanescent wave slab waveguide biosensors are now well established about twenty years after they were demonstrated. They usually rely upon mode excitation from the substrate side, providing a means to measure the bioreaction at the waveguide surface through the monitoring of the conditions of mode excitation. A new readout principle will be presented whereby the incident beam undergoes a sharp and high reflection while being trapped into the biomaterial loaded grating waveguide. The high index metal oxide waveguide and the grating are designed so that the evanescent wave sensitivity is maximum and the conditions for resonant reflection are fulfilled for both polarizations close to normal incidence. Under these conditions, the grating corrugation cannot be located on both sides of the waveguide, as usually preferred, since the grating strength of the TM polarization would be too low. The corrugation must therefore be at the analyte side of the metal oxide layer ; this calls for a specific grating fabrication technology. The option retained for low cost manufacturing is that of wet etching of Ta2O5. This is quite a challenging problem since there is no wet etchant of high density Ta2O5 which does not dissolve standard photoresist, and since the isotropy of wet etching is likely to smooth out the required short period corrugation by underetching. This paper describes the rationale of the design of the reflection interrogation scheme and brings the experimental evidence of the effect obtained on wet etched sensor platforms.

Paper Details

Date Published: 26 February 2004
PDF: 8 pages
Proc. SPIE 5252, Optical Fabrication, Testing, and Metrology, (26 February 2004); doi: 10.1117/12.513695
Show Author Affiliations
Valerie Brioude, Univ. Jean Monnet Saint-Etienne (France)
LTSI-CNRS (France)
Rachida Saoudi, Univ. Jean Monnet Saint-Etienne (France)
LTSI-CNRS (France)
Daniele Blanc, Univ. Jean Monnet Saint-Etienne (France)
LTSI-CNRS (France)
Stephanie Reynaud, Univ. Jean Monnet Saint-Etienne (France)
LTSI-CNRS (France)
Svetlen Tonchev, Institute of Solid State Physics (Bulgaria)
Nikolai M. Lyndin, General Physics Institute (Russia)
James Molloy, Labsystems Affinity Sensors (United Kingdom)

Published in SPIE Proceedings Vol. 5252:
Optical Fabrication, Testing, and Metrology
Roland Geyl; David Rimmer; Lingli Wang, Editor(s)

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