Ultrafast and Inexpensive Microfabrication of Flexible Electrodes for Neural Recording/Stimulation Based on DC Electrophoresis Deposition and Nano-Titanium Dioxide

A flexible microelectrode array (fMEA) for neural recording/stimulation based on platinum (Pt) nanospheres was microfabricated by an ultrafast and inexpensive method enabled by direct current (DC) electrophoresis deposition and nano-titanium dioxide (nano-TiO
₂
). To avoid the great mismatch between the rigid metal layer and the soft polymer substrate, we introduced a polydopamine (PDA) buffer layer to graft Pt nanospheres to polyimide (PI) substrates, and TiO
₂
was added to accelerate the photosynthesis of PDA from ~24h to ~2h. We further used DC electrophoresis to selectively deposit PDA/TiO
₂
/Pt to pattern fMEA and minimize the PDA synthesis to only 10-20 mins, which is 72 times faster than the best record reported. Compared with conventional fMEA with Ti/Pt deposited by sputtering, the as-fabricated fMEA with patternable PDA/TiO
₂
/Pt electrodes have significantly lower impedance (reduced by 99.3%) and better cathodic charge storage capacity (CSC
_c
, increased by 94 times). This method will also greatly benefit the development of inexpensive, high-performance flexible electronics.