Intracellular sensing with transparent graphene-nanotube electrodes.

Transparent electrodes based on graphene are ideal for multimodal cell sensing. However, the atomically flat basal plane of graphene limits the applications largely to capacitive detection of extracellular signals. Here, we develop a biocompatible graphene-carbon nanotube (CNT) hybrid (Bio-GCH), consisting of a graphene substrate covalently decorated with sparsely distributed CNT structures. Bio-GCH electrodes enable low-bias (~4 V) nano-electroporation of cardiomyocytes and high-quality intracellular recordings, with CNTs serving as the dominant electrical transduction channel. At the same time, Bio-GCH electrodes retain the key advantages of graphene electrodes, including high optical transparency, electrical mobility, electrochemical stability, and biocompatibility.