Sensitivity enhancement of a graphene–barium titanate-based surface plasmon resonance biosensor with an Ag–Au bimetallic structure in the visible region

In this study, a surface plasmon resonance (SPR) biosensor based on graphene–barium titanate nanocomposites is optimized by using an Ag–Au bimetallic configuration to achieve sensitivity enhancement. The angular interrogation method is used for the analysis of the reflectance from the sensor. By optimizing parameters, a sensitivity and figure of merit as high as 294°/RIU and 42.13 1/RIU can be obtained with Ag–Au bimetallic film at a wavelength of 633 nm. Compared with conventional SPR biosensors with a single metal film, the sensitivity of the proposed biosensor with Ag–Au bimetallic film can be greatly enhanced. Also, Au thin film can be used as a protective layer to prevent oxidation of the Ag layer.