Sensitive Precise pH Measurement with Large-Area Graphene Field-Effect Transistors at the Quantum-Capacitance Limit

Abstract

Graphene field-effect transistors are attractive for sensing applications, offering high charge-carrier mobility and relatively inexpensive device fabrication. However, integrating high-quality analyte-selective layers on graphene without spoiling its properties remains a challenge. The authors solve the problem for thin layers of metal oxide on large-area high-mobility graphene, which respond to acidity. These structures operate at the limit of quantum capacitance and Nernstian response, achieving a detection limit of 0.0001 $p$H units. The same approach could be extended to sensing species other than the proton, by substituting appropriate overlayers.