Actuator Design And Experiment Of A New Piezoelectric Implantable Middle Ear Hearing Device

Sensorineural hearing loss is a major cause of adult deafness. And thenumber of people suffering from this disease is still increasing due to theageing of the society and the influence of modern industrialization, thedemand of hearing aid devices rises accordingly. Most sensorineural hearingloss are treated with conventional air conduction hearing aids. To solve theproblems brought with conventional air conduction hearing aids such as earplug, the sound negative feedback, etc., the middle ear implantable hearingaids got into research and development since the1970s. At present, the studyabout IMEHDs has gained extensive attention abroad, and correlativeproducts have been launched into market. However, domestic research in thisfiled is at the initial stage and still no commercial products are availabletemporarily.For this reason, funded by the National Natural Science Fund, thispaper is devoted to the design and research of a middle ear implant, aiming todevelop a cost-effective middle ear implantable hearing system and establishthe middle ear implant design development process. A new kind of incusdiving type middle ear implant, which contains a stack of piezoelectriccrystals in a compact structure and a position adjustment apparatus, isestablished in this paper. In the design process, the response characteristics ofthe incus were acquired based on the finite element model of the middle earsystem, this provided a reference for the design of the actuator. Then the finiteelement method was used to estimate the performance of the actuator, mainlythe resonance frequency and the output displacement of device. Thenconsidering of the actual implanting operation circumstance, fixed and supporting devices were designed to ensure the actuator’s flexible adjustmentand reliable fixation during the operation process.Upon the manufacture of the devices, the vibration displacement andfrequency response characteristic of the actuator were tested with a laservibrometer. Finally the hearing compensation ability of the designed middleear implant was acquired through the temporal bone experiment. It isconfirmed that stapes displacement under actuator stimulation at6.9Vrms washigher than that under acoustic stimulation at90dB SPL over the operatingfrequency range, which can be applied to compensate the hearing loss.