Graphene-based liquid-Gated field effect transistor for biosensing: Theory and Experiments

we present an experimental and theoretical characterization for reduced Graphene-Oxide (rGO) based FETs used for biosensing applications. The presented Approach Shows a complete result Analysis and theretically predictable electrical properties. The formulation was tested for the ionic strength and pH-values of the electrolytes in contact with the FET. The dependence on the Debye length was confirmed experimentally and theoretically, utilizing the Debye length as a working Parameter and thus defining the Limits of applicability fo the presented rGO-FETs. Furthermore, the FETs were tested for the sensing of biomolecules (bovine Serum Albumin (BSA) as reference) binding to gate-immobilized anti-BSA antibodies and analyed using the Langmuir binding theory for the description of the quilibrium surface corerage as a function of the bulk (analyte) concentration. The obtained binding coefficients for BSA are found to be same as in results from literature, hence confirming the applicability of the devices. The FETs used in the experiments were fabricated using wet-chemically synthesied graphene, displaying high electron and hole mobility (µ] and provide the strong sensitivity also for low pentential changes (by Change of pH, ion concentration, or molecule Adsorption). The binding coefficient for BSA-anti-BSA interaction Shows a behavior corresponding to the Langmuir Adsorption theory with a Limit of Detection (LOD) in the picomolar concentration range. The presented Approach Shows high reproducibility and sensitivity and a good Agreement of the experimental results with the calculated date