Computational Modeling of ZnO-NRs and Graphene Nanostructure as a Glucose Biosensor

The coupling of a 2-D Graphene layer (GR) with 1-D ZnO nanorods (ZnO-NRs) has wide applications in biosensor devices. GR is a distinguished material with high surface area, high electrical and thermal conductivities, while ZnO wurtzite structure is a multifunctional semiconducting material with unique properties such as piezoelectricity. Combining the interesting features of those two materials make them good candidates for biosensing applications. This work demonstrates the design and modeling of GR/ZnO-NRs/GR sandwiched nanostructure using COMSOL Multiphysics simulation software for glucose biosensing applications. The finite element method (FEM) was used for solving the partial differential equations with various parameters. Various models of the ZnO-NRs array anchored between two supporting GR layers were studied. The variation of the resulting electric potential as a function of applied glucose concentrations for various lengths of ZnO-NRs and various thicknesses of graphene layers were simulated for glucose biosensor models. The simulation results show that increasing ZnO-NRs length and decreasing GR thickness enhances the sensor performance. The sensitivity of the designed sensors was in the range (0.12 to 0.28 mV/mM) for a biosensor with single ZnO-NR and (0.035 to 0.135 mV/mM) for GR/ZnO-NRs/GR) which are quite comparable to the experimental results obtained in other biosensors with different nanostructures. This suggests for the first time that such type of sandwiched GR/ZnO-NRs/GR can be a potential candidate for quite low glucose concentrations.