Abstract
In this research, we have developed a multi-channel piezoelectric acoustic sensor (McPAS) that mimics the function of the natural basilar membrane capable of separating incoming acoustic signals mechanically by their frequency and generating corresponding electrical signals. The McPAS operates without an external energy source and signal processing unit with a vibrating piezoelectric thin film membrane. The shape of the vibrating membrane was chosen to be trapezoidal such that different locations of membrane have different local resonance frequencies. The length of the membrane is 28 mm and the width of the membrane varies from 1 mm to 8 mm. Multiphysics finite element analysis (FEA) was carried out to predict and design the mechanical behaviors and piezoelectric response of the McPAS model. The designed McPAS was fabricated with a MEMS fabrication process based on the simulated results. The fabricated device was tested with a mouth simulator to measure its mechanical and piezoelectrical frequency response with a laser Doppler vibrometer and acoustic signal analyzer. The experimental results show that the as fabricated McPAS can successfully separate incoming acoustic signals within the 2.5 kHz–13.5 kHz range and the maximum electrical signal output upon acoustic signal input of 94 dBSPL was 6.33 mVpp. The performance of the fabricated McPAS coincided well with the designed parameters.
Highlights
The human basilar membrane plays an important role in analyzing the frequencies of incoming soundwaves
The base of a basilar membrane that is close to the oval window is thick, with a short breadth giving it high rigidity and the apex is thin with a long breadth giving it high flexibility
Stereocilia that project from the top of hair cells inside the cochlear are arranged underneath a basilar membrane
Summary
The human basilar membrane plays an important role in analyzing the frequencies of incoming soundwaves. Békésy defined the phenomenon of frequency separation studying the structure of the basilar membrane within a cochlea [1]. Stereocilia that project from the top of hair cells inside the cochlear are arranged underneath a basilar membrane. Patients having severe hearing loss from damaged cochlea cannot benefit from hearing aids that just amplifies incoming acoustic signals and need a cochlear implant to restore their hearing. Conventional cochlear implants consist of a microphone for converting sound into electrical signals, a signal processor for handling the converted electrical signals, an inductive coil for transmitting the processed electrical signal from outside to inside the body, and an electrode array for stimulating nerve cells. Some researchers have studied the development of generation cochlear implants that are superior to conventional cochlear implants
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