Improving adhesion strength between layers of an implantable parylene-C electrode

Parylene-C (PC) is one of the most frequently used materials for flexible implantable electrode. Its interface with metal or other PC layer is critical in PC-metal-PC “sandwich” implantable neural electrodes in relation to their long-term reliability. In this study, we aim to develop a method to improve metal-PC and PC-PC adhesion in PC-based neural electrodes. “Nano-forest” structure, composed of nanopillar array is fabricated on the surface of bottom PC by oxygen reactive ion etching (RIE). The contribution of this layer of nano-structure to mechanical adhesion and sealing property are evaluated respectively. The results verify that for PC based “sandwich” electrode, not only the mechanical adhesion among three layers, but also the sealing ability between PC layers are significantly improved.