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Proceedings Paper

Tagless remote refractometric sensor based on WGMs in quantum dot-embedded microspheres
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Paper Abstract

Optical resonances in microspheres have recently been applied to biosensing applications. The resonances, known as Whispering Gallery Modes (WGMs) result from the total internal reflection of the light propagating inside the high index spherical surface within a lower index medium. The evanescent field of the WGM, which extends beyond the microsphere surface, is sensitive to the changes in the local refractive index in the surrounding medium. The high Q factor associated with WGMs enables a highly sensitive sensor element. Here we present a refractometric sensor with high sensitivity based on quantum dot (QD) embedded polystyrene microspheres. Ultrashort laser pulses are used to induce two photon excited luminescence from the QDs inside the microspheres. By optimizing the detection area of the microsphere, an enhanced resonance signal to background ratio can be achieved. Theoretical calculations of the resonance peak shifts are compared with the experimental data. Refractometric sensing based on WGMs is a technique that does not require analyte labeling. In this work, QDs are used as a local, broadband light source within the microspheres to enable remote excitation of the resonant modes. The sensor has great potential in many biosensing applications.

Paper Details

Date Published: 22 February 2008
PDF: 12 pages
Proc. SPIE 6863, Optical Diagnostics and Sensing VIII, 686303 (22 February 2008); doi: 10.1117/12.763730
Show Author Affiliations
Shuo Pang, Texas A&M Univ. (United States)
Kenith E. Meissner, Texas A&M Univ. (United States)

Published in SPIE Proceedings Vol. 6863:
Optical Diagnostics and Sensing VIII
Gerard L. Coté; Alexander V. Priezzhev, Editor(s)

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