3D Patterned Thin-Film Electrodes for Neural Prosthetics-Proof of Concept.

The applications of polyimide (PI) based thin-film electrodes in neural implants has been steadily increasing in the last decades. Beside the advantages of factors such as size reduction and chemical inertness, the adhesion between PI and metals lacks the necessary robustness for chronic implantation [1]. Adhesion promoters like silicon carbide (SiC) and titanium help increase the long-term stability [1]–[3]. However crack formation is still probable in thin-film metallization of active contact sites, which can lead to detrimental thin-film metal delamination. This work presents our process to integrate 3D groove structures into the active contact sites, thereby reducing the probability of crack formation. The contact sites were entirely covered with a sputtered iridium oxide film (SIROF) and showed more conformable electrochemical properties compared to regular planar SIROF contact sites.