A microelectromechanical system artificial basilar membrane based on a piezoelectric cantilever array and its characterization using an animal model

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.

Thin Film PZT Acoustic Sensor for Fully Implantable Cochlear Implants

“…Results show that the proposed design has a clear frequency selectivity with a minimum quality factor of 1285 and mimics the natural operation of cochlea. Both the sensitivity and the quality factor of the proposed system are higher than the state-of-the-art piezoelectric transducers [4]. 3.…”

“…The output of the piezoelectric acoustic sensor is going to be processed by an interface circuit and converted into current pulses which are sent to corresponding electrodes to stimulate the auditory neurons. Experimental results show that the device generates 200 mVpp at 100 dB Sound Pressure Level (SPL) which is the required sensing voltage of state-of-the-art neural stimulation circuitry [4]. High output voltages make implementation of the FICI systems more feasible.…”

Fabrication of Si3N4-Based Artificial Basilar Membrane with ZnO Nanopillar Using MEMS Process

“…In 2011, Professor Ito's group at Tohoku University reported a study using a 40 m thick piezoelectric film [10]. In addition, a research paper on ABM experiment using piezoelectric cantilever was presented by Professor Hongsoo Choi's group at DGIST in Korea in 2015 [12]. However, there has been no report on the development of artificial cochlear having continuous membrane capable of sound signal transmission in the similar fashion to that of human hair cell on the basilar membrane (BM).…”

“…Since the resonant frequency varies depending on the position of the basilar membrane, this functions as a frequency analyzer [8,9]. For biomimetic artificial basilar membrane (ABM), the frequency classification of basilar membranes depends on the principle of tonotopy [10][11][12]. Thus, the ABM covers all ranges of audible frequencies and induces local resonance in specific frequencies, at the same time.…”

Bulk PZT Cantilever Based MEMS Acoustic Transducer for Cochlear Implant Applications

“…Up to 9.8 nW/cm 2 of power density was reported at 100 dB-SPL using thin film lead-zirconate-titanate (PZT) MEMS acoustic energy harvesters [2]. A piezoelectric cantilever array reported by Jang et al uses thin film AlN piezoelectric transducers [3], but the generated voltage is on the order of 50 μV and requires an external power source for neural stimulation. In a previous study of our group, Beker et al theoretically investigated the bulk piezoelectric energy harvesters attached on a flat ear drum model and verified the efficiency of using bulk PZT for power generation in CIs [4].…”