Flexible device could treat hearing loss without batteries

Date:
October 27, 2021
Source:
American Chemical Society
Summary:
Some people are born with hearing loss, while others acquire it with
age, infections or long-term noise exposures. In many instances,
the tiny hairs in the inner ear's cochlea that allow the brain to
recognize electrical pulses as sound are damaged. As a step toward
an advanced artificial cochlea, researchers report a conductive
membrane, which translated sound waves into matching electrical
signals when implanted inside a model ear, without requiring
external power.



FULL STORY ==========================================================================
Some people are born with hearing loss, while others acquire it with age, infections or long-term noise exposures. In many instances, the tiny hairs
in the inner ear's cochlea that allow the brain to recognize electrical
pulses as sound are damaged. As a step toward an advanced artificial
cochlea, researchers in ACS Nano report a conductive membrane, which
translated sound waves into matching electrical signals when implanted
inside a model ear, without requiring external power.


==========================================================================
When the hair cells inside the inner ear stop working, there's no way to reverse the damage. Currently, treatment is limited to hearing aids or
cochlear implants. But these devices require external power sources and
can have difficulty amplifying speech correctly so that it's understood
by the user. One possible solution is to simulate healthy cochlear hairs, converting noise into the electrical signals processed by the brain as recognizable sounds. To accomplish this, previous researchers have tried self-powered piezoelectric materials, which become charged when they're compressed by the pressure that accompanies sound waves, and triboelectric materials, which produce friction and static electricity when moved by
these waves. However, the devices aren't easy to make and don't produce
enough signal across the frequencies involved in human speech. So, Yunming
Wang and colleagues wanted a simple way to fabricate a material that
used both compression and friction for an acoustic sensing device with
high efficiency and sensitivity across a broad range of audio frequencies.

To create a piezo-triboelectric material, the researchers mixed barium
titanate nanoparticles coated with silicon dioxide into a conductive
polymer, which they dried into a thin, flexible film. Next, they removed
the silicon dioxide shells with an alkaline solution. This step left
behind a sponge-like membrane with spaces around the nanoparticles,
allowing them to jostle around when hit by sound waves. In tests, the researchers showed that contact between the nanoparticles and polymer
increased the membrane's electrical output by 55% compared to the pristine polymer. When they sandwiched the membrane between two thin metal grids,
the acoustic sensing device produced a maximum electrical signal at 170
hertz, a frequency within the range of most adult's voices.

Finally, the researchers implanted the device inside a model ear and
played a music file. They recorded the electrical output and converted it
into a new audio file, which displayed a strong similarity to the original version. The researchers say their self-powered device is sensitive to
the wide acoustic range needed to hear most sounds and voices.

The authors acknowledge funding from the General Program of the National Natural Science Foundation of China, the Fundamental Research Funds
for the Central Universities and the Double First-Class-Independent Innovation-Subject Construction.

========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Jiaqi Zheng, Zhaohan Yu, Yunming Wang, Yue Fu, Dan Chen, Huamin
Zhou.

Acoustic Core-Shell Resonance Harvester for Application of
Artificial Cochlea Based on the Piezo-Triboelectric Effect. ACS
Nano, 2021; DOI: 10.1021/acsnano.1c04242 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211027121953.htm

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