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-TiO2). 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 nano spheres to polyimide (PI) substrates, and TiO2 was added to accelerate the photosynthesis of PDA from similar to 24h to similar to 2h. We further used DC electrophoresis to selectively deposit PDA/TiO2/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/TiO2/Pt electrodes have significantly lower impedance (reduced by 99.3%) and better cathodic charge storage capacity (CSCe, increased by 94 times). This method will also greatly benefit the development of inexpensive, high-performance flexible electronics.