Enhanced mechanical and electrical performance of Ti/Au microelectrode arrays using a pre-cured polyimide substrate

This paper presents an approach for fabricating flexible neural electrodes with improved adhesion and low impedance through optimization of the PSPI curing process. The fabrication involves a two-step process in which thin-film metallization is performed on a partially cured photosensitive polyimide (PSPI) substrate, followed by a final curing process after metal electrode patterning. The effects of the PSPI curing condition on the adhesion and electrical characteristics of the Ti/Au thin-film electrodes were systematically investigated. The enhanced metal adhesion was quantitatively evaluated using a tape test, while the electrical characteristics were characterized through electrochemical impedance and phase measurements after complete curing of the polymer substrate. The flexible neural electrodes fabricated using the proposed process exhibited an impedance of 9.96 kΩ at 1 kHz, compared with 36.24 kΩ for electrodes fabricated using the conventional fully cured PSPI process. These results demonstrate that controlling the PSPI curing condition during electrode fabrication can improve metal–polymer adhesion while maintaining favorable electrical characteristics.