Development of Ultrasensitive Biomimetic Auditory Hair Cells Based on Piezoresistive Hydrogel Nanocomposites

Abstract

With an ageing population, hearing disorders are predicted to rise considerably in the following decades. Thus, developing a new class of artificial auditory system has been highlighted as one of the most exciting research topics for biomedical applications. Herein, a design of a biocompatible piezoresistive-based artificial hair cell sensor is presented consisting of a highly flexible and conductive polyvinyl alcohol (PVA) nanocomposite with vertical graphene nanosheets (VGNs). The bilayer hydrogel sensor demonstrates excellent performance to mimic biological hair cells, responding to acoustic stimuli in the audible range between 60 Hz to 20 kHz. The sensor output demonstrates stable mid-frequency regions (∼4–9 kHz), with the greatest sensitivity as high frequencies (∼13–20 kHz). This is somewhat akin to the mammalian auditory system, which has remarkable sensitivity and sharp tuning at high frequencies due to the “active process”. This work validates the PVA/VGN sensor as a potential candidate to play a similar functional role to that of the cochlear hair cells, which also operate over a wide frequency domain in a viscous environment. Further characterizations of the sensor show that increasing the sound amplitude results in higher responses from the sensor while taking it to the depth drops the sensor outputs due to attenuation of sound in water. Meanwhile, the acoustic pressure distribution of sound waves is predicted through finite element analysis, whereby the numerical results are in perfect agreement with experimental data. This proof-of-concept work creates a platform for the future design of susceptible, flexible biomimetic sensors to closely mimic the biological cochlea.

Morphological Fabrication of Equilibrium and Auditory Sensors through Electrolytic Polymerization on Hybrid Fluid Rubber (HF Rubber) for Smart Materials of Robotics

“…In contrast, the hair cells at the innermost cochlea are sensible to low frequency. The investigation to demonstrate the auditory process has been conducted in previous studies [ 32 , 33 , 44 ].…”

A biomimetic orthogonal flow sensor based on an asymmetric optical fiber sensory structure for marine sensing

“…Unfortunately, these methods are either complex or require large and expensive equipment, and they are difficult to integrate into other marine exploration equipment, such as unmanned underwater vehicles or marine buoys. Given the growing interests in oceanic exploration and exploitation, various novel flow sensors have been developed, such as mechanical-based or micromechanical-based flow sensors [4][5][6][7], vortex-induced sensors [8,9], computer-vision-based sensors [10], and bionic flow sensors [5,[11][12][13][14][15][16][17][18][19][20][21].…”

“…Guided by this structure, researchers have developed various bioinspired flow sensors with artificial cupula and stress-sensing elements underneath as sensory hair cells to detect the flow of liquid. One bioinspired flow sensor is the electronics sensor using microelectromechanical systems (MEMS) as the sensing element, and various MEMS sensors based on cantilever structures using different materials and technologies have been proposed [11][12][13][14][15][16][17][18][19]. Despite the admirable performances of MEMS flow sensors, problems such as device damage or instability caused by strong conductivity and corrosion of seawater still need to be solved.…”

3D‐Printed Artificial Cilia Arrays: A Versatile Tool for Customizable Mechanosensing

“…Piezoresistive sensing involves creating changes in the electrical conductance of a substrate upon compression or strain when a cilium is bent from physical perturbation such as under the influence of air or liquid flow. [21,22] Capacitive sensing relies on the disturbance of the cilia inducing physical changes on the underlying substrate, differentially increasing or decreasing the gap between capacitive plates and modifying capacitance. [19,23] Magnetic sensing utilizes a magnetically polarized cilium, which when bent induces a stray field that is detectable by magnetic sensing substrates.…”