Simulation of the working range of an implantable hearing aid transducer by use of different piezoelectric materials

摘要

A piezoelectric membrane transducer which offers an approach to treat sensorineural hearing loss is introduced. The sensor and the actuator element each consist of a titanium membrane with a single crystal piezo and are clamped into the same assembly housing. The transducer is placed into the incudostapedial joint gap (between incus and stapes ossicle) which offers a straightforward implantation after the drilling of an access through a mastoidectomy which is state of the art for otology surgeries. The sensor is measuring the force transmitted through the ossicular chain onto his membrane on the incus-side of the housing. An associated signal processing drives the actuator at the opposite side of the sensor to amplify the movement transmitted by the ossicular chain to the inner ear. The movement of the stapes footplate is related to the hearing perception. Therefore the proposed concept can be used as part of a fully implantable hearing aid. A finite elemente model (FEM) of a transducer is built and implemented in a existing FEM model of the middle ear. Both sensor and actuator performance span up a working range for the transducer which ranges from about 20 to 30 dB SPL up to 90 to over 120 dB SPL. In this study the range of the workspace is evaluated in dependency of the chosen piezoelectric material which can lead to significant changes of the results.