title: Single virus detection from the reactive shift of a whispering-gallery mode.
abstract: We report the label-free, real-time optical detection of Influenza A virus particles. Binding of single virions is observed from discrete changes in the resonance frequency/wavelength of a whispering-gallery mode excited in a microspherical cavity. We find that the magnitude of the discrete wavelength-shift signal can be sufficiently enhanced by reducing the microsphere size. A reactive sensing mechanism with inverse dependence on mode volume is confirmed in experiments with virus-sized polystyrene nanoparticles. By comparing the electromagnetic theory for this reactive effect with experiments, the size and mass ( approximately 5.2 x 10(-16) g) of a bound virion are determined directly from the optimal resonance shift.
authors.affiliation: The Rowland Institute, Harvard University, Cambridge, MA 02142, USA. vollmer@rowland.harvard.edu
authors.forename: F
authors.initials: F
authors.lastname: Vollmer
authors.forename: S
authors.initials: S
authors.lastname: Arnold
authors.forename: D
authors.initials: D
authors.lastname: Keng
mesh_terms: D009980:Influenza A virus / Q000737:chemistry*; D007834:Lasers; D055095:Optics and Photonics / Q000379:methods*; D012680:Sensitivity and Specificity; D014771:Virion / Q000737:chemistry*