A Parylene-Silicon Cochlear Electrode Array with Integrated Position Sensors

A thin-film cochlear electrode array has been developed for a cochlear prosthesis to achieve improved sound perception and position accuracy. The array is fabricated using a bulk-silicon micromachining process that allows parylene deposition and patterning at wafer level, followed by a wet silicon release etch that is compatible with the use of boron etch-stops. The process is capable of realizing arrays with substrates stressed to hug the modiolar wall in the rest state and whose stiffness can be adjusted over a wide range. Built-in tip and curvature sensors respond to tip contact and bending-induced shank stress, respectively during in-vitro and in-vivo implants. The process is also compatible with the integration of parylene ribbon cables for lead transfer to an implanted electronics package.