Bilayer Nanomesh Structures for Transparent Recording and Stimulating Microelectrodes

• Published in: Advanced functional materials 2017-12, Vol.27 (48), p.n/a
• Main Authors: Qiang, Yi, Seo, Kyung Jin, Zhao, Xuanyi, Artoni, Pietro, Golshan, Negar H., Culaclii, Stanislav, Wang, Po‐Min, Liu, Wentai, Ziemer, Katherine S., Fagiolini, Michela, Fang, Hui
• Format: Article
• Language: English
• Subjects: bilayer nanomeshes; Bilayers; Biocompatibility; Brain; Charge injection; Electrochemical analysis; Electrode materials; Electrodes; Electroplating; Gold; Impedance; iridium oxide; Materials science; Microelectrodes; PEDOT:PSS; templated electrodeposition; transparent microelectrodes
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.201704117

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. Transparent metal‐based bilayer nanomesh microelectrodes serve as promising neural interfaces for simultaneous electrophysiology with optical imaging and optogenetics, enabling both high temporal and spatial resolution of neural recording and stimulation. By electrodepositing low‐impedance coatings on gold nanomesh microelectrodes, a significant decrease of impedance and a boost of charge injection limit are achieved, while preserving high transmittance.