Design and analysis of a microelectromagnetic vibration transducer used as an implantable middle ear hearing aid

Abstract

In this paper, we present the design and analysis of a microelectromagnetic vibration transducer for an implantable middle ear hearing aid, characterized by small size, high efficiency and selective frequency bandwidth. The electromagnetic vibration transducer is used to convert electrical energy, which is obtained from sound signals generated externally, into mechanical vibration energy, which is a means of amplifying acoustic sound for patients with sensory neural hearing loss. The electromagnetic vibration transducer can be partially implanted at a sound bridge of bone which is composed of the ossicular chain that couples the eardrum to the cochlea. For use as an implantable middle ear hearing aid, this vibration transducer must consider design parameters, such as transducer size, vibration force and frequency. The vibration transducer should have the critical size to be partially implanted at the ossicular chain in the middle ear space. The maximum vibration force of the transducer requires more than 9.6 dyne, which is according to 100 dB SPL to be compensated sound pressure level. The vibration frequency of the transducer is in the speech signal frequency range of about 100 Hz to 5 kHz. To do this, we present a new type of electromagnetic vibration transducer that is composed of a wound coil, permanent magnet and a four-beam cross silicon elastic body. In this paper we show the techniques for optimizing the electromagnetic driving part and the four-beam silicon elastic body to obtain large vibration force output and selective frequency bandwidth by using theoretical analysis and finite element analysis simulation.