Abstract
We proposed a piezoelectric artificial basilar membrane (ABM) composed of a microelectromechanical system cantilever array. The ABM mimics the tonotopy of the cochlea: frequency selectivity and mechanoelectric transduction. The fabricated ABM exhibits a clear tonotopy in an audible frequency range (2.92–12.6 kHz). Also, an animal model was used to verify the characteristics of the ABM as a front end for potential cochlear implant applications. For this, a signal processor was used to convert the piezoelectric output from the ABM to an electrical stimulus for auditory neurons. The electrical stimulus for auditory neurons was delivered through an implanted intra-cochlear electrode array. The amplitude of the electrical stimulus was modulated in the range of 0.15 to 3.5 V with incoming sound pressure levels (SPL) of 70.1 to 94.8 dB SPL. The electrical stimulus was used to elicit an electrically evoked auditory brainstem response (EABR) from deafened guinea pigs. EABRs were successfully measured and their magnitude increased upon application of acoustic stimuli from 75 to 95 dB SPL. The frequency selectivity of the ABM was estimated by measuring the magnitude of EABRs while applying sound pressure at the resonance and off-resonance frequencies of the corresponding cantilever of the selected channel. In this study, we demonstrated a novel piezoelectric ABM and verified its characteristics by measuring EABRs.
Highlights
Frequencies according to its width, thickness, and stiffness
The results demonstrated that the artificial BMs (ABMs) with a signal processor and intra-cochlear electrode array could induce an auditory evoked potential from deafened guinea pigs, with clear frequency selectivity by way of an implanted intra-cochlear electrode array
The total volume of the ABM was 2.5 × 2.5 × 0.6 mm[3], which is sufficiently small for implantation in the external auditory meatus or tympanic membrane[37,38]
Summary
Frequencies according to its width, thickness, and stiffness. The basal region responds to high-frequency sounds, while the apical region reacts to low-frequency sounds. Tanaka et al.[11] and Xu et al.[12] proposed a micro-cantilever array that mimics the mechanical performance of the BM Another parameter that can be varied to mimic the appropriate frequency selectivity is the membrane width of an ABM. The performance of CIs is acceptable, the requirement to wear an external processor that communicates with the implanted device via a radio-frequency coil increases the power consumption, limits the activities that can be undertaken while wearing the device, leads to some patients feeling stigmatized and contributes to the high cost of these devices[30,31,32,33] To overcome these limitations, researchers have attempted to develop a next-generation CI that integrated a microfabricated ABM8,9,15,16,25,33,34
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