Extremely stable virus sensing using graphene FET with suppressed drift characteristics due to reduction of gate leakage current by passivation layer

Abstract We have improved the drift characteristics of the graphene FET biosensor that have been a great problem in the previous graphene FET biosensing, enabling stable virus detection. Among the various origins of the drift characteristics, we found out the gate leakage current through the ionic electrolyte solution between the reference gate electrode and the metal source/drain electrodes exposed to the solution attributes largely to the drift characteristics. Moreover, this gate leakage current decreases over time and shows the drift characteristics. The gate leakage current was dramatically suppressed by passivating the source/drain metal electrodes with the photoresist (SU-8) and/or SiO 2 . As a result, the drift slope of the substrate with the passivation layer is improved and becomes one-sixth of that without the passivation layer. Furthermore, the electrical charge of SARS-CoV-2 could be clearly detected by suppressing the drift characteristics using the antibody modified graphene field-effect transistor with the passivation layer.