Hot embossing of poly(lactic acid) films for an embedded cochlear implant stiffener

Abstract

Externally attached stiffeners/actuators are required for providing structural rigidity to flexible parylene-based cochlear implants for maintaining a perimodiolar shape in the post-implantation phase. Such backing devices being bulky add dead volume to the implant making the fluid-filled scala tympani chamber more congested during insertion resulting in shallow insertion depth. A thin film parylene array with integrated stiffener will provide a smaller implant cross-section potentially allowing a deeper implantation. A novel fabrication method for embedded cochlear implant stiffener structures by hot embossing of poly(lactic acid) (PLA) films is reported. PLA packaging film has been hot embossed on parylene coated silicon substrates using a custom fixture. Embossing results show good pattern transfer fidelity. Rigidity of the embossed stiffeners has been compared with the structural rigidity of poly (ethylene terephthalate) actuators.

A Backing Device Based on an Embedded Stiffener and Retractable Insertion Tool for Thin-Film Cochlear Arrays

“…Component geometries simplified for aid in visualizing the overall system (not drawn to scale). Reprinted from[79] with permission from Springer.…”