Modelling effective charge density in graphene-gased DNA sensor

Due to its unique properties, including high conductivity, large surface area and significant mechanical strength, graphene has attracted a great deal of attention among researchers in physics, biology, nanoelectronics and nanotechnology fields, especially over the past few years. A fundamental understanding of the DNA-hybridization detection mechanism and technical prediction and optimization of many graphene-based DNA sensors requires extensive modeling and simulation of devices. Although there have been numerous experimental studies in this field, the lack of analytical models is felt deeply. In this work, to start with modelling, a liquid field effect transistor-based structure is employed as a platform, and graphene charge density variation based on the Poisson-Boltzman equations are studied under the impact induced by the adsorption of different values of DNA concentration on its surface. The effect of DNA molecules concentration and surface charge density of ssDNA and dsDNA before and after hybridization are considered in the calculation of the analytical model. The obtained current-voltage characteristics of the proposed model are compared with available experimental data existing, and a good agreement is found. For all the concentrations considered in this work, the proposed model can track experimental curves documented by other authors, with acceptable accuracy