Here we demonstrate a new concept for designing an ultra-sensitive deformed cavity biosensor. Owning to the breaking of rotational symmetry, the field distribution is not uniform along the cavity boundary and results in the dependence of spectra shif
t and mode splitting on the position of a scatter. In this case, the deformed cavity sensor can be extremely sensitive to the location of particle binding on the cavity boundary. Moreover, the directional emission from the deformed microcavity provides a possibility to detect a single particle or molecule in the far field.
