Sub-mm encapsulated accelerometers: a fully implantable sensor for cochlear implants

We present, for the first time, a submillimeter sized fully packaged accelerometer as an alternative sensor for use in cochlear implants and middle ear implants. The sensor is as small as 387/spl times/387/spl times/230 /spl mu/m and weighs approximately 100 /spl mu/g. This miniaturization is realized by utilizing an advanced packaging scheme using a thick film encapsulation with epi-polysilicon. The sensor is attached on the middle ear ossicles and measures the vibration transmitted from the tympanic membrane due to the sound in the ear canal. The sensor is fully characterized on a human cadaveric temporal bone preparation.