Three-Dimensional Microelectrode Array with Vertically-Aligned Carbon Nanotubes for Retinal Neural Signal Recording

We developed the first carbon nanotube (CNT) -based three-dimensional (3D) microelectrode array (MEA) capable of penetrating retinal tissue and directly recording neural activities by integrating vertically-aligned carbon nanotubes (VACNTs) onto metal electrodes. Capillary-induced wetting densified the CNT strands, optimizing the microstructure for retinal tissue penetration. The VACNT microstructure effectively penetrated the retinal tissue surface, leveraging its stress-concentrating shape and high stiffness. Additionally, the fabricated 3D microelectrode showed remarkably low impedance (3.6 kΩ), utilizing a large specific surface area of VACNTs. The microelectrodes successfully recorded the spontaneous spiking activities of a retinal ganglion cell from an ex-vivo mouse retina.