Taking single virus detection and sizing to the limit with molecular sensitivity: The birth of nanoplasmonic-microcavity hybrid sensors

The BioPhotonics community is buzzing at the prospect that ulta-small bio-nanoparticles such as Polio virus and protein can be detected label-free in their native state and sized one at a time. As the awareness that the claim of label-free single protein sensing through the frequency shift of a bare microcavity by A.M. Armani et al in Science in 2007 fades from lack of independent experimental confirmation or a viable physical mechanism to account for the magnitude of the reported wavelength shifts, a new approach has captured the community's interest. It is a product of a marriage between nano-optics and micro-photonics, and is poised to take label-free sensing to the limit.