Neural Electrode\nBased on 3D Microscale/Nanoscale\nPorous Graphene Structures for Neural Stimulation

Conventional neural electrodes, made from flat and smooth\nmetals\nsuch as platinum and gold, face challenges due to their low charge\nstorage capacity and charge injection capacity, high impedance, poor\nelectrochemical stability, and limited mechanical flexibility. Here,\nwe present high-performance neural electrodes based on 3D microscale/nanoscale\nporous graphene structures derived from transparent fluorinated polyimide\nfor efficient neural stimulation. 3D micro/nanoscale porous graphene\nstructure is formed using a scalable, low-cost, and single-step laser\nphotothermal manufacturing technique, providing an enhanced specific\nsurface area, a high charge storage capacity of 362.4 mC cm<sup>–2</sup>, and a charge injection capacity of 10.32 mC cm<sup>–2</sup>. The charge storage capacity of our neural electrode is more than\n2 orders of magnitude higher than that of monolayer graphene and gold\nelectrodes due to its integrated micropores and high specific surface\narea, facilitating efficient electrolyte ion penetration and subsequent\ncharge accumulation. 3D micro/nanoscale porous graphene-based neural\nelectrodes also demonstrate high endurance, exceeding 1 million stimulation\ncycles, and exhibit remarkable flexibility and conformability, ideal\nfor close contact with nerves during stimulation. Furthermore, the\ncombination of high charge storage capacity and the transparency of\nthe fluorinated polyimide film makes it a suitable material for future\napplications that require simultaneous nerve stimulation and imaging-based\nnerve identification.