Micro-wrinkle strategy for stable soft neural interface with optimized electroplated PEDOT:PSS

A highly reliable neural interface is required in long-term neural signal recording in vivo for neuroscience research and the treatment of neurological disorders. Organic poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is a promising candidate for a next-generation neural interface material due to its better faradaic charge transfer and capacitive charge coupling than metal electrodes such as Au or Pt. However, its weak adhesion to underlying metallic layers impedes its application with significant cracks or delamination. Here, a MEMS-compatible strategy is proposed to obtain wrinkled microelectrodes based on oil-pretreated elastomer substrate to improve the electrochemical performance and stability of electroplated PEDOT:PSS coating. To discover the optimized electroplating parameters, the galvanostatic electroplating method is applied with incremental time from 0 to 500 s. The modified wrinkled microelectrodes with electroplating time of 300 s permits 10 000 cyclic voltammetry scanning cycles without cracks nor significant change in charge storage capacity or electrochemical impedance, whereas the cracks and delamination appear when the electroplating time increases to 500 s.