Highly sensitive biosensor with graphene-MoS2 heterostructure based on photonic spin Hall effect

Abstract

Abstract We propose a new optical biosensor based on photonic spin Hall effect (PSHE) for detection of DNA hybridization. This device consists of BK7 prism, Ag, SiO2, Au and graphene-MoS2 heterostructure which produces waveguide coupled surface plasmon resonance (WCSPR) effect to enormously enhance PSHE. The adsorption of graphene-MoS2 heterostructure to biomolecules changes the refractive index of the sensing medium, thereby affecting spin-dependent splitting in PSHE. The 2 × 2 transfer matrix method is applied to calculate the generalized Fresnel reflection and we deduce the reflected light shifts in PSHE. We study the correlation between spin-dependent displacements and the refractive index variations of sensed solution to obtain the highest sensitivity in the proposed sensor. However, the PSHE exists in the proposed biosensor is extremely weak, so a signal enhancement technology called weak measurement is adopted to amplify the PSHE shift. Thus, the proposed biosensor can successfully detect the hybridization of probe DNA with target DNA. These results may provide practical applications for PSHE in biological monitoring, medical diagnosis, and food safety.