Carbon nanotube electrode

Carbon nanotubes (CNTs), rolled graphene cylinders with extreme aspect ratio, high electrical conductivity, and chemical stability, are grown or deposited as forests, films, or composites on neural contacts. Their nanoscale roughness and enormous specific surface area lower impedance and raise charge capacity, while the porous topography promotes tight neuronal adhesion and neurite outgrowth, improving the electrode-tissue coupling.

CNTs are used both as a standalone porous coating and as a filler that toughens conducting-polymer films (PEDOT-CNT composites). Honest caveats: alignment and adhesion are hard to control at scale, and there are long-standing biocompatibility and toxicology questions about free or shed nanotubes, so chronically implanted designs favor firmly anchored, entangled, or encapsulated CNT architectures rather than loose fibers.