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Published April 12, 2011 | Published
Journal Article Open

High sensitivity nanoparticle detection using optical microcavities


We demonstrate a highly sensitive nanoparticle and virus detection method by using a thermal-stabilized reference interferometer in conjunction with an ultrahigh-Q microcavity. Sensitivity is sufficient to resolve shifts caused by binding of individual nanobeads in solution down to a record radius of 12.5 nm, a size approaching that of single protein molecules. A histogram of wavelength shift versus nanoparticle radius shows that particle size can be inferred from shift maxima. Additionally, the signal-to-noise ratio for detection of Influenza A virus is enhanced to 38:1 from the previously reported 3:1. The method does not use feedback stabilization of the probe laser. It is also observed that the conjunction of particle-induced backscatter and optical-path-induced shifts can be used to enhance detection signal-to-noise.

Additional Information

© 2011 National Academy of Sciences. Freely available online through the PNAS open access option. Edited by Amnon Yariv, California Institute of Technology, Pasadena, CA, and approved February 25, 2011 (received for review December 3, 2010). Published online before print March 28, 2011. Fig. 1 was prepared by Benjamin Taylor and Xuan Du at Department of Electrical and Computer Engineering, University of Victoria. The work was supported in part by Defense Advanced Research Planning Agency and Natural Sciences and Engineering Research Council (Canada). Author contributions: T.L. and K.V. designed research; T.L., H.L., and K.V. performed research; J.-H.K. contributed new reagents/analytic tools; T.L., H.L., T.C., S.E.F., R.C.F., and K.V. contributed conceptual ideas; T.L., H.L., T.C., S.H., and K.V. analyzed data; and T.L., H.L., T.C., S.H., J.-H.K., S.E.F., R.C.F., and K.V. wrote the paper.

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