Bilayer Nanomesh Structures for Transparent Recording and Stimulating Microelectrodes

Abstract Nanomeshed forms of metal have emerged as a promising biocompatible electrode material for future soft bioelectronics. However, metal/electrolyte interfaces are intrinsically capacitive, severely limiting their electrochemical performance, especially for scaled electrodes, which are essential for high‐resolution brain mapping. Here, an innovative bilayer nanomesh approach is demonstrated to address this limitation while preserving the nanomesh advantage. Electroplating low‐impedance coatings on a gold nanomesh template achieves an impedance < 30 kΩ at 1 kHz and a charge injection limit of 1 mC cm⁻2 for 80 × 80 µm² microelectrodes, a 4.3× and 12.8× improvement over uncoated electrodes, respectively, while maintaining a transparency of ≈70% at 550 nm. Systematic characterization of transmittance, impedance, charge injection limits, cyclic charge injection, and light‐induced artifacts reveal an encouraging performance of the bilayer nanomesh microelectrodes. The bilayer nanomesh approach presented here is expected to enable next‐generation large‐scale transparent bioelectronics with broad utility in biology.