We describe and demonstrate a physical mechanism that substantially enhances the label-free sensitivity of a whispering-gallery-mode biosensor for the detection of individual nanoparticles in aqueous solution. It involves the interaction of dielectric nanoparticle in an equatorial carousel orbit with a plasmonic nanoparticle bound at the microparticle’s equator. As the dielectric particle parks to hot spots on the plasmonic particle we observe frequency shifts that are enhanced by a factor of 4, consistent with a simple reactive model. Once optimized the enhancement by this mechanism should exceed several orders of magnitude, putting individual protein within reach.
Plasmonic enhancement of a whispering-gallery-mode biosensor for single nanoparticle detection
S. I. Shopova, R. Rajmangal, S. Holler, S. Arnold; Plasmonic enhancement of a whispering-gallery-mode biosensor for single nanoparticle detection. Appl. Phys. Lett. 13 June 2011; 98 (24): 243104. https://doi.org/10.1063/1.3599584
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