Cochlear amplifier inspired two-channel active artificial hair cells

Davaria, Sheyda; Malladi, V. V. N. Sriram; Motaharibidgoli, Seyedmostafa; Tarazaga, Pablo A.

doi:10.1016/j.ymssp.2019.04.041

Cited by 8 publications

(16 citation statements)

References 25 publications

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“…To overcome the difficulties and unsolved problems with existing implant designs, feedback control mimicking the outer hair cells has been integrated into artificial cochlear sensory epithelia. Some research groups have used feedback control on piezoelectric sensors consisting of a single beam [ 42 , 43 , 44 , 45 ]. Our research group has developed a prototype of an artificial cochlear sensory epithelium capable of frequency selectivity, conversion of mechanical and electrical signals, and feedback control by mimicking the functions of the basilar membrane, the inner hair cells, and the outer hair cells in the cochlea [ 29 ].…”

Section: Introductionmentioning

confidence: 99%

A Preliminary Prototype High-Speed Feedback Control of an Artificial Cochlear Sensory Epithelium Mimicking Function of Outer Hair Cells

Yamazaki

Yamanaka

2020

Micromachines

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A novel feedback control technique for the local oscillation amplitude in an artificial cochlear sensory epithelium that mimics the functions of the outer hair cells in the cochlea is successfully developed and can be implemented with a control time on the order of hundreds of milliseconds. The prototype artificial cochlear sensory epithelium was improved from that developed in our previous study to enable the instantaneous determination of the local resonance position based on the electrical output from a bimorph piezoelectric membrane. The device contains local patterned electrodes deposited with micro electro mechanical system (MEMS) technology that is used to detect the electrical output and oscillate the device by applying local electrical stimuli. The main feature of the present feedback control system is the principle that the resonance position is recognized by simultaneously measuring the local electrical outputs of all of the electrodes and comparing their magnitudes, which drastically reduces the feedback control time. In this way, it takes 0.8 s to control the local oscillation of the device, representing the speed of control with the order of one hundred times relative to that in the previous study using the mechanical automatic stage to scan the oscillation amplitude at each electrode. Furthermore, the intrinsic difficulties in the experiment such as the electrical measurement against the electromagnetic noise, adhesion of materials, and fatigue failure mechanism of the oscillation system are also shown and discussed in detail based on the many scientific aspects. The basic knowledge of the MEMS fabrication and the experimental measurement would provide useful suggestions for future research. The proposed preliminary prototype high-speed feedback control can aid in the future development of fully implantable cochlear implants with a wider dynamic range.

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Section: Introductionmentioning

confidence: 99%

A Preliminary Prototype High-Speed Feedback Control of an Artificial Cochlear Sensory Epithelium Mimicking Function of Outer Hair Cells

Yamazaki

Yamanaka

2020

Micromachines

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“…Although researchers have attempted to develop various control algorithms to achieve a cochlea-like performance (Lechner, 1993; Lim and Park, 2009; Tapson et al, 2010), the majority of them are unable to mimic the one-third compressive rate of the mammalian cochlea. Among these active AHC designs, the authors’ recent studies have shown that a multi-channel active AHC can be modeled as a piezoelectric bimorph cantilever subject to a base excitation and a control voltage actuation (Davaria et al, 2019a, 2019b). The phenomenological cubic damping control law first introduced by Joyce (2015) and Joyce and Tarazaga (2013, 2014a, 2014b, 2015a, 2015b) was extended to control the response of the AHC near its first two natural frequencies.…”

Section: Introductionmentioning

confidence: 99%

“…This work provides a solution to the challenging problem of omitting permanent external sensors from the feedback loop of the AHC systems while mimicking the cochlear amplifier. Furthermore, in contrast to the systems with velocity feedback (Davaria et al, 2019a; Joyce, 2015; Joyce and Tarazaga, 2014b), the output of the self-sensing AHC is the piezo-electric voltage. In the second part of this study, the self-sensing AHC model will be validated experimentally.…”

Section: Introductionmentioning

confidence: 99%

Self-sensing active artificial hair cells inspired by the cochlear amplifier, Part I: Theoretical and numerical realization

Davaria

Tarazaga

2022

Journal of Intelligent Material Systems and Structures

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The mammalian cochlear amplifier displays a unique nonlinear characteristic of amplifying or compressing the acoustic stimuli based on their level. Designing control algorithms for artificial hair cells (AHCs) with active sensing capabilities could mimic such dynamics. The present work focuses on developing a novel self-sensing active AHC scheme that implements the amplification/compression function of the AHCs and extends the authors’ previous designs for future cochlear implants or sensor design applications. The AHC functions near a Hopf bifurcation and varies the output piezoelectric voltage by a power-law relationship with the input. It is the first time that a self-sensing AHC is modeled as a quadmorph cantilever controlled by a phenomenological cubic damping controller. The AHC’s control signal is supplied to a pair of its piezoelectric layers and the output of the AHC is the sensed voltage of the second piezoelectric pair. This is in contrast to the previous studies where the AHC’s tip-velocity was measured with external sensors. The requirement of permanent external sensors in the system was a strict limitation that is eliminated in this work. An in-depth study of this novel AHC is conducted in this paper and AHC’s implementation is examined experimentally in Part II of the paper.

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“…However, two commonly known bottlenecks in the development of fully insertable cochlear implants are (1) the lack of power available to stimulate the nerve using biocompatible materials and (2) the difficulty of achieving a reproducible frequency range within the dimensions of the cochlea. We [ 17 , 18 , 29 ] and other groups [ 30 , 31 , 32 , 33 ] addressed the former issue by developing a nonlinear feedback control system that mimics the amplification of outer hair cells. However, there have been few studies of microdevices being implanted in the cochlea, and their performance, particularly in terms of mechanical dynamics, has yet to be thoroughly established.…”

Section: Introductionmentioning

confidence: 99%

Oscillation Characteristics of an Artificial Cochlear Sensory Epithelium Optimized for a Micrometer-Scale Curved Structure

Yamazaki

Kohno

2022

Micromachines

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Based on the modern microelectromechanical systems technology, we present a revolutionary miniaturized artificial cochlear sensory epithelium for future implantation tests on guinea pigs. The device was curved to fit the spiral structure of the cochlea and miniaturized to a maximum dimension of <1 mm to be implanted in the cochlea. First, the effect of the curved configuration on the oscillation characteristics of a trapezoidal membrane was evaluated using the relatively larger devices, which had a trapezoidal and a comparable curved shape designed for high-precision in vitro measurements. Both experimental and numerical analyses were used to determine the resonance frequencies and positions, and multiple oscillation modes were clearly observed. Because the maximum oscillation amplitude positions, i.e., the resonance positions, differed depending on the resonance frequencies in both trapezoidal and curved membrane devices, the sound frequency was determined based on the resonance position, thus reproducing the frequency selectivity of the basilar membrane in the organ of Corti. Furthermore, the resonance frequencies and positions of these two devices with different configurations were determined to be quantitatively consistent and similar in terms of mechanical dynamics. This result shows that despite a curved angle of 50–60°, the effect of the curved shape on oscillation characteristics was negligible. Second, the nanometer-scale oscillation of the miniaturized device was successfully measured, and the local resonance frequency in air was varied from 157 to 277 kHz using an experimental system that could measure the amplitude distribution in a two-dimensional (2D) plane with a high accuracy and reproducibility at a high speed. The miniaturized device developed in this study was shown to have frequency selectivity, and when the device was implanted in the cochlea, it was expected to discriminate frequencies in the same manner as the basilar membrane in the biological system. This study established methods for fabricating and evaluating the miniaturized device, and the proposed miniaturized device in a curved shape demonstrated the feasibility of next-generation cochlear implants.

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Cochlear amplifier inspired two-channel active artificial hair cells

Cited by 8 publications

References 25 publications

A Preliminary Prototype High-Speed Feedback Control of an Artificial Cochlear Sensory Epithelium Mimicking Function of Outer Hair Cells

A Preliminary Prototype High-Speed Feedback Control of an Artificial Cochlear Sensory Epithelium Mimicking Function of Outer Hair Cells

Self-sensing active artificial hair cells inspired by the cochlear amplifier, Part I: Theoretical and numerical realization

Oscillation Characteristics of an Artificial Cochlear Sensory Epithelium Optimized for a Micrometer-Scale Curved Structure

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