Cavity Ring-down Biosensing

Cavity ring-down spectroscopy (CRDS) is an established technique for gases sensing that is newly emerging in the field of optical biosensing. This approach measures changes in the rate of decay of light injected into an optical resonator and relates them to optical loss along its length. This principle has recently been adapted for use in liquids, providing a highly sensitive method for quantitative biosensing applications. Such approaches, which can incorporate evanescent field sensing elements, have been demonstrated for the detection of molecular absorption in liquids, absorption of surface bound species and scattering response of individual cells. Building on the high sensitivity that CRDS brings to molecular spectroscopy instrumentation, evanescent wave CRDS represents the current state of the art holds significant potential for a range of biosensing applications.