Abstract
Cochlear hair cells are critical for the conversion of acoustic into electrical signals and their dysfunction is a primary cause of acquired hearing impairments, which worsen with aging. Piezoelectric materials can reproduce the acoustic-electrical transduction properties of the cochlea and represent promising candidates for future cochlear prostheses. The majority of piezoelectric hearing devices so far developed are based on thin films, which have not managed to simultaneously provide the desired flexibility, high sensitivity, wide frequency selectivity, and biocompatibility. To overcome these issues, we hypothesized that fibrous membranes made up of polymeric piezoelectric biocompatible nanofibers could be employed to mimic the function of the basilar membrane, by selectively vibrating in response to different frequencies of sound and transmitting the resulting electrical impulses to the vestibulocochlear nerve. In this study, poly(vinylidene fluoride-trifluoroethylene) piezoelectric nanofiber-based acoustic circular sensors were designed and fabricated using the electrospinning technique. The performance of the sensors was investigated with particular focus on the identification of the resonance frequencies and acoustic-electrical conversion in fibrous membrane with different size and fiber orientation. The voltage output (1–17 mV) varied in the range of low resonance frequency (100–400 Hz) depending on the diameter of the macroscale sensors and alignment of the fibers. The devices developed can be regarded as a proof-of-concept demonstrating the possibility of using piezoelectric fibers to convert acoustic waves into electrical signals, through possible synergistic effects of piezoelectricity and triboelectricity. The study has paved the way for the development of self-powered nanofibrous implantable auditory sensors.
Highlights
Piezoelectric materials possess the special ability to produce an electrical voltage in response to a mechanical force, which makes them suitable for a wide range of applications, including sensors, transducers, energy harvesting, and biomedical devices.[1−4] Some of these are based on acoustic resonators, which enable the conversion of acoustic sound into electricity and, eventually, can be designed to resonate at specific frequencies when stimulated with acoustic waves, thereby achieving the desired sound frequency selectivity
The present results provide a proof of principle to drive the downscaling engineering of electrospun fiber-based sensors toward more suitable designs of implantable devices
The structural characteristics, the local electromechanical properties, and the response to acoustic stimuli of piezoelectric membrane devices based on P(VDFTrFE) random and aligned fibers produced by electrospinning have been thoroughly investigated
Summary
Piezoelectric materials possess the special ability to produce an electrical voltage in response to a mechanical force, which makes them suitable for a wide range of applications, including sensors, transducers, energy harvesting, and biomedical devices.[1−4] Some of these are based on acoustic resonators, which enable the conversion of acoustic sound into electricity and, eventually, can be designed to resonate at specific frequencies when stimulated with acoustic waves, thereby achieving the desired sound frequency selectivity These conversion mechanisms can be used to restore the auditory function, in the case of sensorineural hearing loss, by developing artificial basilar membranes with piezoelectric properties. This triggers the release of neurotransmitters at the base of the inner hair cells, activating the cochlear spiral ganglion neurons, which transfer the signal
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