Silicon nanowire and graphene FET sensors as new reference electrodes in electrolytic environments

O. Knopfmacher, A. Tarasov, W. Fu, C. Nef, J. Kurz, K. Bedner, M. Wipf, M. Calame, C. Schönenberger
University of Basel, CH

Keywords: ISFET, Sensor, (bio-)chemical sensing, reference electrodes

Summary:

Today, there is a growing need for sensing devices offering rapid and portable analytical functionality with high sensitivity at the molecular level. The development of reliable, flexible and label-free sensing systems at reasonable costs is a challenging task. Nano-scale electronic transducers such as nanowires or graphene based on a field field-effect transistor (FET) implementation have a great potential as electronic (bio-) chemical sensors due to their small size and their high sensitivity. However such a platform requires differential readout capability with in situ reference electrodes to prevent miss-reading. For dynamical binding and unbinding experiments in electrolytic environments, integrated reference electrodes are crucial elements. Here we present two successful paths in achieving nano-scaled on-chip reference electrodes using silicon nanowires and graphene. Both devices show no response for changes in the bulk pH. Hence, it allows the integration of nano-scaled FETs as reference electrodes in electrolytic environment. Our approach holds great promise in the use of integrateable solid-state reference electrodes.