Graphene-Based Electrolyte-Gated Field-Effect Transistors for Potentiometrically Sensing Neuropeptide Y in Physiologically Relevant Environments

Wearable electronics with real-time biosensing capabilities are very important for future applications in monitoring and augmenting human health and performance. Graphene-based potentiometric sensing offers a route for developing wearable sensors that can selectively sense biomarkers in biofluids such as sweat and saliva. This manuscript studies the sensitivity of potentiometric sensors made with graphene-based electrolyte-gated field-effect transistors (GFETs). Selectivity in the sensor toward a nanoscale biomarker, neuropeptide Y (NPY), was achieved by functionalizing graphene with a peptide-based biorecognition element. The sensors were then characterized extensively by varying concentrations of NPY in a complex medium containing artificial sweat with varying ionic concentrations and pH. This medium, therefore, emulated the response of the sensor to biomarkers in a physiologically relevant condition approaching a real-world scenario. Analysis using Gouy–Chapman–Stern theory for the liquid–solid interface at nanoscale highlighted important features of potentiometric sensing such as log-linear response and charge screening effects in GFET sensors.