Evaluation of an implantable piezoelectric floating mass transducer for sensorineural hearing loss

In this paper, a piezoelectric floating mass transducer (PFMT) which consists of a multi-layered piezoelectric actuator and a metal case has been evaluated for its suitability as a transducer in implantable middle ear hearing device (IMEHD) for mild-to-severe sensorineural hearing loss. Like the VIBRANT ME-DEL’s FMT ®, the PFMT can be attached to the incus long process with a metal clamp and vibrate the ossicular chain according to the force originated from the piezoelectric actuator’s expansion-and-contraction. An in vitro experiment using a human temporal bone confirms that the PFMT excitation at 3.5 V rms can generate vibration displacements being equivalent to the sound pressure of about 94 dB SPL below 1 kHz and about 140 dB SPL at 8 kHz. The PFMT’s power consumption to produce 94 dB SPL equivalent sound stimulation is 65 μW at 1 kHz. Therefore, the PFMT is expected to be a useful transducer with advantages such as simple surgical implantation, no interference from external electromagnetic fields, and an improved productivity.