Analysis of an Optofluidic Biochemical Sensor

We introduce a novel optofuidic biochemical sensor in which detection is based on the contrast between the refractive index of a target biomaterial and ambient carrier fluid. The sensor consists of parallel vertical micochannels embedded in a planar substrate. The central microchannel is illuminated by a focused beam of light and the periodic spacing of the channels combined with the contrast in refractive index between the fluid and the substrate act to confine and guide the incident light down through the central channel. Sensing is achieved via accumulation of a nanoscale layer of target biomaterial on the surfaces of the the microchannels. This layer causes a shift in the optical transmission spectrum of light passing through the substrate. We demonstrate the viability of the sensor using full-wave electromagnetic analysis and study its transmission spectrum at optical wavelengths as a function of layer thickness and refractive index.