All-Inkjet-Printed Graphene-Gated Organic Electrochemical Transistors on Polymeric Foil as Highly Sensitive Enzymatic Biosensors

We demonstrate fully inkjet-printed graphene-gated Organic Electrochemical Transistors (OECTs) on polymeric foil for the enzymatic-based biosensing of glucose. The graphene-gated transistors exhibit better linearity, repeatability, and sensitivity than printed silver-gated devices studied in this work and other types of printed devices previously reported in the literature. Their limit of detection is 100 nM with a normalized sensitivity of 20 %/dec in the linear range of 30 to 5000 M glucose concentrations, hence comparable with state-of-the-art OECT devices made by lithography processes on rigid substrates and with complex multi-layer gates. Electrochemical impedance spectroscopy analysis shows that the improved sensitivity of the graphene-gated devices is related to a significant decrease of the charge-transfer resistance at the graphene electrode-electrolyte interface in the presence of glucose. The optimized sensing method and device configuration are also extended to the detection of the metabolite lactate. This study enables the development of fully-printed high-performance enzymatic OECTs with graphene sensing-gates for multi-metabolites sensing.