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Whispering-gallery modes in dielectric microspheres for biosensing applications

Borri, Paola, Lutti, Julie and Langbein, Wolfgang 2009. Whispering-gallery modes in dielectric microspheres for biosensing applications. Presented at: nternational Conference on Transparent Optical Networks, Sao Miguel Azores, Portugal, 28 June-2 July 2009. ICTON 2009 11th International Conference on Transparent Optical Networks: Ponta Delgada University, S. Miguel, Azores, Portugal, 28th June-2nd July 2009. New York: Institute of Electrical and Electronics Engineers, pp. 1-3. 10.1109/ICTON.2009.5185193

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A dielectric microsphere in a lower refractive index medium exhibits sharp optical resonances, called whispering gallery modes. These are sensitive probes of refractive index changes near the sphere surface and can be thus exploited for biosensing applications. Using evanescent field coupling via frustrated total internal reflection, we measured whispering gallery optical resonances of polystyrene microspheres of 30-45 mum diameter, held in aqueous buffer by optical tweezers, and found Q-factors of up to 4 times 106. We also demonstrated a monolithic sensor based on polystyrene microspheres in water attached onto an optical coupler via a solid separation layer index matched to water. As a proof of principle of the sensing capabilities, we measured the response to refractive index changes and inferred a shot-noise limited precision of 1 times 10-8 refractive index units.

Item Type: Conference or Workshop Item (Paper)
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QC Physics
Q Science > QH Natural history > QH301 Biology
Uncontrolled Keywords: biosensors , whispering gallery modes
Publisher: Institute of Electrical and Electronics Engineers
ISBN: 9781424448258
Last Modified: 08 Aug 2019 20:15

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