E-coli identification using Kretschmann-based Ag/GO nanocomposites plasmonic sensor

Abstract

A low cost and highly efficient surface plasmon resonance (SPR) sensor for e-coli detection was developed by employing Kretschmann prism coupling technique. Silver thin film and graphene oxide were deposited on top of hypotenuse side of prism surface to excite surface plasmon polaritons (SPP). Their thicknesses were modulated between 43nm to 49nm and 1nm to 15nm respectively. The excitations of SPP were investigated by monitoring its minimum reflectance, Q-factor values and amount of angle shifting. Hybrid nanolayers of 1nm GO which was coated on top of 43nm- 45nm silver thin film exhibited excellent sensitivity resulting maximum angle shifting about 0.30°. As thicknesses of silver exceeded 45nm, the generation of SPR signals were less significant which led to the degradation of sensor's sensing performance. In conclusion, the sensitivity of SPR sensors for the identification of e-coli can be optimized by introduced nanocomposites silver-GO with total thicknesses between 44nm and 46nm. Optimum sensitivity can only be achieved by employing maximum thickness of 1nm GO.