Graphene Biotransistor Interfaced with a Nitrifying Biofilm

Abstract

Using a graphene field-effect transistor bio- sensor, we monitored the pH inside a living biofilm with fast temporal resolution (∼1 s) over multihour time periods. The atomically thin sensor is positioned between the biofilm and a supporting silicon oxide surface, providing noninvasive access to conditions at the base of the biofilm. We determine the transient changes in pH when the biofilm metabolizes substrate molecules and when it is exposed to biocide. The pH resolution is approximately 0.01 pH units when using 1 s time averaging. The sensor drift is approximately 0.01 pH units per hour. Our results demonstrate the potential of this technology to study biofilm metabolism and monitor biofilm health.