Development of a new plasmonic transducer for the detection of biological species

An optical switch configuration is demonstrated as a promising approach for the detection of proteins based on preliminary work consisting of the detection of variations in the bulk refractive index. The device comprises a corrugated dielectric grating covered by chrome and gold, featured by a high depth-to-period ratio, allowing switching SPR detection. This grating is placed inside a fluidic cell through which solutions are injected. Bulk sensing is demonstrated by the successive injection of four mixtures of water and glycerol in different concentrations. The refractive indices of these solutions have a 2×10^-3 RIU increment. Their detection has been obtained with a signal-to-noise ratio of 735.