Single virus detection from the reactive shift of a whispering-gallery mode

F. Vollmer, S. Arnold, D. Keng

Research output: Contribution to journalArticlepeer-review


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 (≈5.2 × 10-16 g) of a bound virion are determined directly from the optimal resonance shift.

Original languageEnglish (US)
Pages (from-to)20701-20704
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number52
StatePublished - Dec 30 2008


  • Biosensor
  • Influenza
  • Optical resonance

ASJC Scopus subject areas

  • General


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