In-SituGrowth of Platinum Nanowires on Polydopamine for Enhancing Mechanical and Electrochemical Properties of Flexible Microelectrode Arrays

Polydopamine (PDA)-based biomimetic materials have attracted much attention due to the outstanding adhesion and biocompatibility, etc. However, developing a generalized and simple approach for the patternable polymer coatings in a liquid environment and the secondary modification for high-resolution electrodes are challengeable. Herein, A high-performance flexible microelectrode arrays (fMEAs) for biomedical applications based on novel platinum nanowire (PtNW) was proposed using PDA as the bioinspired adhesive buffer layer between the polymer substrate and the nanowire layer. The PDA film was patternable and selectively grafted on the flexible PI substrate using the micro-contact printing ( $\mu $ CP) technique, followed by the reduction of PtNW on patterned PDA in chloroplatinic acid (H ₂ PtCl ₆ ) by in situ electroless deposition. The as-fabricated PI-PDA/PtNW electrode has greatly reduced the electrochemical impedance at 1 kHz by 99.54% compared with that of PI-Ti/Pt using the conventional sputtering method, and also increased the charge storage capacity (CSCc) by 27 times. At the same time, the adhesion between the metal layer (PDA/PtNW or Ti/Pt) and the PI substrate was evaluated using both intense ultrasonic bath and torsion fatigue test. The results showed that PDA was very effective as the adhesive layer by significantly enhancing both mechanical adhesion and impedance stability when suffering mechanical stress. These achievements are of great interest for robust flexible electronics for implantable or wearable biomedical applications.