Design and analysis of graphene–MoS₂ hybrid layer based SPR biosensor with TiO₂–SiO₂ nano film for formalin detection: numerical approach

In this paper, a Surface Plasmon Resonance (SPR) biosensor has been numerically developed that used Graphene–MoS₂–Au–TiO₂–SiO₂ hybrid structure for the detection of formalin. This developed sensor has been sensed the presence the formalin based on attenuated total reflection (ATR) method by observing the change of “surface plasmon resonance angle-the change of minimum reflectance attributor” and “the resonance frequency characteristics (RFC)-maximum transmittance attributor”. Chitosan has been used as probe sensing medium to accelerate particular reaction with the formalin. Here, graphene is used as biomolecular recognition element because of its high adsorption ability and optical characteristics which helps to improve sensor sensitivity, MoS₂ used for it has larger band gap, high fluroscence quenching ability, higher optical absorption efficiency, TiO₂–SiO₂ bilayer as the improvement of sensitivity and Gold (Au) as the sharp SPR curve. Numerical results give the impression that the variation of RFC and SPR angle for improper sensing of formalin is quiet negligible that confirms no formalin is detected whereas for proper sensing these change are considerably countable that confirms the detection of formalin. From the sensor sensitivity analysis, owing to add TiO₂–SiO₂ bilayer with Graphene–MoS₂ Hybrid layer, maximum sensitivity of 85.375% has been numerically resulted. This high sensor performance is for taking advantages of Graphene surface high selectively which detect bio molecular compounds through pi-stacking force, larger work function (5.1 eV) of MoS₂ which allows the high sensitive detection of bio targets and Rich plasmon happens at the TiO₂–SiO₂ interface.