Enhanced nanoparticle detection with liquid droplet resonators

Year: 2014

Authors: Foreman M. R., Avino S., Zullo R., Loock H.-P., Vollmer F., Gagliardi G.

Autors Affiliation: Laboratory of Nanophotonics and Biosensing, Max-Planck-Institute for the Science of Light, Günther-Scharowsky-Straße 1, 91058, Erlangen, Germany;
Consiglio Nazionale delle Ricerche, Istituto Nazionale di Ottica (INO), via Campi Flegrei 34 — Comprensorio A. Olivetti, 80078, Pozzuoli, Naples, Italy;
Department of Chemistry, Queen’s University, Kingston, K7L 3N6, Ontario, Canada

Abstract: Whispering gallery mode particle sensing experiments are commonly performed with solid resonators, whereby the sensing volume is limited to the weak evanescent tail of the mode near the resonator surface. In this work we discuss in detail the sensitivity enhancements achievable in liquid droplet resonators wherein the stronger internal fields and convenient means of particle delivery can be exploited. Asymptotic formulae are derived for the relative resonance shift, line broadening and mode splitting of TE and TM modes in liquid droplet resonators. As a corollary the relative fraction of internal and external mode energy follows, which is shown to govern achievable sensitivity enhancements of solute concentration measurements in droplet sensors. Experimental measurements of nanoparticle concentration based on whispering gallery mode resonance broadening are also presented.

Journal/Review: EUROPEAN PHYSICAL JOURNAL-SPECIAL TOPICS

Volume: 223 (10)      Pages from: 1971  to: 1988

More Information: M.R.F. and F.V. acknowledge financial support from an Alexander von Humboldt Fellowship and the Max Planck Society respectively. H.-P. L. acknowledges support from the Natural Sciences and Engineering Research Council (NSERC) of Canada. Experimental work (S. A., R.Z. and G. G.) was funded by the Italian Ministry for Education & Research (MIUR) via project PON code B91H11000630005 \”Monica\”. The authors are also grateful to P. De Natale, A. Giorgini and P. Malara (CNR-INO) for helpful discussions, and F. Castelluccio (CNR-ICB) for support in chemical procedures.
KeyWords: Whispering-gallery modes; Optical resonators; Sensing applications; Resonance shifts; Refractive-index; Mie scattering; Fused-silica; Microcavity; Single; Microspheres
DOI: 10.1140/epjst/e2014-02240-9

Citations: 15
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