| In this work, we present two Micro Electromechanical Systems (MEMS) based implantable microelectrode arrays for use in auditory prostheses. A novel curvature-controlled 3D micro-electrode array for cochlear implants has been fabricated with the conducting polymer polypyrrole, which deforms upon the application of an external electric field. This electric field is used to control the curvature of the electrode, facilitating its surgical insertion while minimizing mechanical trauma to the scala tympani of the cochlea. In addition, the curved electrode hugs the modiolus, reducing the distance between the electrodes and the target neurons. The result is improved stimulation effectiveness in terms of tonotopic specificity and stimulation threshold. We have both simulated and demonstrated operation of the displacement of the electrode array.;An alternative to cochlear implants is direct interface with the auditory nerve by way of penetrating electrode arrays. A more accurate tonotopic representation may be functionally restored if an electrode array with very small contact area is placed directly within the auditory nerve instead of in the scala tympani. We have explored a novel intraneural auditory prosthesis, consisting of a form-fitting implantable microelectrode array. A three-dimensional, high-aspect ratio, and high-density electrode array has been developed using bulk machining technology. A varying-length electrode array has also been created, which will span a broader spatial area within the auditory fiber and decrease the number of redundant electrodes. A low-power low-noise complementary metal oxide semiconductor (CMOS) chip has been designed and tested for neural signal recording.;Based on the second microelectrode, a wireless implantable microsystem for auditory prostheses has been proposed. With a CMOS chip flip-chip bump bonded onto the electrode array, it will eliminate the need for interconnection between the electronic chip and the MEMS electrode. This wireless and integrated design can be applied to other neural prostheses, including retinal and vestibular implants. |
