UC San Diego

Electrophysiological studies of electrogenic cells help elucidate, diagnose, and modulate cellular electrical activities. Transmembrane potentials are the manifest of microscopic ionic events and set the bases for macroscopic electrophysiological characteristics of tissues and organs. Research in this field is largely driven by the versatile tools to precisely record transmembrane potentials of a single cell and a cellular network. The gold-standard patch clamp, in various forms, is challenging to simultaneously interface different cells due to their poor maneuverability and massive invasiveness during operations. An ideal sensor needs to be in direct contact with the cytoplasm to record intracellular events, based on transistors with minimal access impedance and wide bandwidth at a reduced device size, and scalable to interrogate multiple cells in parallel. Existing nanostructured sensors lack one or more of those requirements. Based on these motivations, we report a three-dimensional (3D) field effect transistor (FET) array made by a compressive buckling technique. The 3D geometry allows penetrating the cell membrane and recording low-magnitude subthreshold signals inside the cell. A phospholipid coating on the 3D FETs facilitates the spontaneous internalization of the FET into the cytoplasm with minimal invasiveness. Using the 3D FET array, we can record intra- and inter-cellular signal propagation of cardiomyocytes. Also, we demonstrate intracellular recording of cardiomyocytes in a 3D cardiac tissue construct. This platform technology will help acquire new insights into electrical behaviors in cellular networks and other broad basic electrophysiological studies.