Voltage readout from a piezoelectric intracochlear acoustic transducer implanted in a living guinea pig

Abstract

The ability to measure the voltage readout from a sensor implanted inside the living cochlea enables continuous monitoring of intracochlear acoustic pressure locally, which could improve cochlear implants. We developed a piezoelectric intracochlear acoustic transducer (PIAT) designed to sense the acoustic pressure while fully implanted inside a living guinea pig cochlea. The PIAT, fabricated using micro-electro-mechanical systems (MEMS) techniques, consisted of an array of four piezoelectric cantilevers with varying lengths to enhance sensitivity across a wide frequency bandwidth. Prior to implantation, benchtop tests were conducted to characterize the device performance in air and in water. When implanted in the cochlea of an anesthetized guinea pig, the in vivo voltage response from the PIAT was measured in response to 80–95 dB sound pressure level 1–14 kHz sinusoidal acoustic excitation at the entrance of the guinea pig’s ear canal. All sensed signals were above the noise floor and unaffected by crosstalk from the cochlear microphonic or external electrical interference. These results demonstrate that external acoustic stimulus can be sensed via the piezoelectric voltage response of the implanted MEMS transducer inside the living cochlea, providing key steps towards developing intracochlear acoustic sensors to replace external or subcutaneous microphones for auditory prosthetics.

Tunable Piezoelectricity of Multifunctional Boron Nitride Nanotube/Poly(dimethylsiloxane) Stretchable Composites

“…BNNTs and their composites should also demonstrate direct piezoelectricity, [ 26 ] generating voltage when deformed, motivating our exploration of BNNT/PDMS composites as active materials for vibration detection and energy harvesting. BNNT/PDMS composites were fabricated into cantilever‐type vibration harvesters (see Vibration Harvesting in the Supporting Information) based on the design of piezoelectric acoustic detectors which generate voltage in response to sound‐induced cantilever oscillation [ 38 ] (Figure S9a, Supporting Information). Cantilevers were then subject to kHz frequency range sound, 1, 5, and 7.5 kHz, which is relevant for structural and voice vibration monitoring.…”

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

“…However, amplifiers producing a 1000-fold [ 37 ], 100-fold [ 38 ], and 950-fold [ 39 ] signal amplification were needed to stimulate the auditory nerves in these studies because the eABR threshold requires an electrical potential on the order of volts but the electrical signals from organic piezoelectric materials are generally small. Some papers have reported the measurement of electrical signals from piezoelectric devices implanted in animal cochleae [ 37 , 40 ]. Maximum voltage outputs of 29.3 μV [ 37 ] and 79.7 μV [ 40 ] were recorded, and these are small to stimulate the auditory nerves.…”

“…Some papers have reported the measurement of electrical signals from piezoelectric devices implanted in animal cochleae [ 37 , 40 ]. Maximum voltage outputs of 29.3 μV [ 37 ] and 79.7 μV [ 40 ] were recorded, and these are small to stimulate the auditory nerves.…”

Utilizing Electrocochleography as a Microphone for Fully Implantable Cochlear Implants

“…However, due to stability issues of placement on the middle ear ossicles, carrying this out in-vivo is a challenging prospect. Additionally, Zhao and colleagues were able to demonstrate the feasibility of designing and using an intracochlear location of a piezoelectric transducer (micro-electro-mechanical systems xylophone) in a guinea pig model 31 . Here there is a probe that courses within the cochlea and is composed of a xylophone-like structure that is designed to resonate at different frequencies in attempts to mimic the fluid dynamics of the inner ear/ basilar membrane.…”