Cu-Grating and Graphene-Assisted SPR-Based Refractive Index Sensor
摘要
In this paper, we propose a surface plasmon resonance (SPR)-based refractive index sensor for biosensing applications. The sensor has a Cu grating formed on an Al layer to excite the surface plasmons (SPs) on a metal dielectric interface. A graphene layer is considered on top of the Cu grating to prevent the corrosion and oxidation of the considered metals and to enhance the adsorption of the analyte molecules. The grooves of the Cu grating are filled with indium tin oxide (ITO) to have uniform deposition of the graphene layer on the grating. The whole structure is formed on a glass substrate. The performance of the proposed sensor has been analyzed for different refractive index values corresponding to three bioanalytes such as hemoglobin, plasma, and platelets, which may play a crucial role in the detection of several diseases like chikungunya, dengue, and malaria. The rigorous coupled wave analysis (RCWA) method has been used to carry out the numerical simulations of the proposed sensor. The sensitivity and quality factor have been used as the performance indicators of the sensor. The thicknesses of the Al layer, grating depth, and number of graphene layers are optimized to maximize the performance of the sensor. Our numerical results show a maximum sensitivity of 295.3 deg./RIU and a quality factor of 443.25 RIU−1. The proposed structure can also be used in designing the SPR-based sensor for medical diagnostics, environmental monitoring, and biosensing.