Vertical Graphene-Based Microelectrode Array Coupled with Microelectroporation for Real-Time Monitoring of Intracellular Action Potential

Multisite intracellular action potential (AP) recording is essential for studying the electrophysiology in excitatory cell networks. Recent approaches combining 3D structure micro/nanoelectrode arrays with perforation technology are promising solutions to achieve multichannel intracellular recording, which remains challenging for conventional microelectrode arrays and patch clamps. However, most of the existing 3D micro/nanoelectrode arrays involved nanoscale photolithographic processes and were less compatible with fabricating 3D-nanostructured carbon electrodes. Here, we present a vertical graphene-based microelectrode array (VG-MEA) integrated with microelectroporation for robust, high-quality multichannel intracellular AP recordings in cardiomyocytes. The VG-MEAs were rapidly fabricated via plasma-enhanced chemical vapor deposition and laser etching, avoiding nanoscale photolithography. The VG microelectrode offers low interfacial impedance and a high surface area, and its 3D structure enhances cell-electrode sealing. The VG-MEA enabled higher quality intracellular AP recordings with longer recording duration (∼6 min), higher SNR (∼45 dB), and higher waveform fidelity compared to planar gold MEAs, planar carbon MEAs, and fuzzy graphene MEAs. The VG-MEA supported repeated microelectroporation cycles within 1 h without impacting cellular behavior. VG-MEA also allowed continuous intracellular recording for up to 9 days and could be robustly reused for 9 cycles within a year. This VG-MEA platform provides promising tools for intracellular electrophysiology research.