A Comprehensive Study on the Theory of Graphene Solution-Gated Field Effect Transistor:Simulations and Experiments

Graphene solution-gated field effect tran-sistors(G-SgFETs)have been widely developed in the field of biosensors,but deficiencies in their theories still exist.A theoretical model for G-SgFET,including the three-terminal equivalent circuit model and the numeric-ally calculating method,is proposed by the comprehens-ive analyses of the graphene-liquid interface and the FET principle.Not only the applied voltages on the electrode-pairs of gate-source and drain-source,but also the nature of graphene and its derivatives are considered by analys-ing their influences on the Fermi level,the carriers'con-centration and mobility,which may consequently affect the output drain-source current.To verify whether it is available for G-SgFETs based on different method pre-pared graphene,three kinds of graphene materials which are liquid-phase exfoliated graphene,reduced graphene oxide(rGO),and tetra(4-aminophenyl)porphyrin hy-bridized rGO are used as examples.The coincidences of calculated output and transfer feature curves with the measured ones are obtained to confirm its adaptivity for simulating the basic G-SgFETs'electric features,by mod-ulating Fermi level and mobility.Furthermore,the model is exploited to simulate G-SgFETs'current responding to the biological functionalization with aptamer and the de-tections for circulating tumor cells,as a proof-of-concept.The calculated current changes are compared with the ex-perimental results,to verify the proposed G-SgFETs'model is also suitable for mimicking the bio-electronic re-sponding,which may give a preview of some conceived G-SgFETs'biosensors and improve the design efficiency.