E. Coli detection using surface plasmon resonance

The high sensitivity of chalcogenide surface plasmon resonance (SPR) structures with chalcogenide films is fructified to elaborate the salinity sensor for the seawater. A four layers configuration was taken into consideration, comprising a BK7 prism, a gold thin film, a chalcogenide As2S3 film and the ambient medium, which is the β-Galactosidase solution. The transfer matrix formalism was used in our study to determine the reflectances characterizing the plasmonic structure. The two polarization modes (TE and TM) were taken into consideration, in order to determine the best configuration that allows an optimal sensitivity. The structure used as optical sensor has a high sensitivity. A 0.05 % change in concentration causes an 18-arc seconds change in plasmonic resonance incident angle and it can be resolved.