Numerical design of high-performance WS2/metal/WS2/graphene heterostructure based surface plasmon resonance refractive index sensor

•We propose a WS2/metal/WS2/graphene heterostructure based SPR sensor.•Finite-difference time-domain method is employed to model the sensor.•The optimized design shows the highest sensitivity of 208 deg/RIU.•The coating of WS2 on both metal surfaces improves the sensor performance greatly. The development of a high-performance bio-sensor utilizing the surface plasmon resonance (SPR) phenomenon has attracted great attention recently as a promising and precise sensing technology. Here, we proposed a WS2/metal/WS2/graphene heterostructure based SPR sensor with improved performances. The finite-difference time-domain (FDTD) technique was employed to model and develop the prospective sensor. The effects of integrating different layers, the analyte thickness on the performance of the sensor, and the electric field distribution were investigated systematically. We found that the optimized structure of the developed sensor exhibits the highest sensitivity of 208 deg/RIU with a detection accuracy of 1.12 and a quality factor of 223.66 RIU−1, which is superior to existing two-dimensional material based SPR sensors. The enhancement of light-material interaction caused by the coating of a monolayer WS2 on both sides of the metal improved the sensor performance significantly. These findings demonstrate a new way of performance enhancement in the composite layer sensor, aimed at further improving the identification of specific biomolecules such as glucose, blood disease, environmental monitoring, and agricultural applications.