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SPECIALITY
Flexible device could treat
hearing loss without batteries
ome people are born with
hearing loss, while others
Sacquire it with age, infections
or long-term noise exposures. In An electrically
many instances, the tiny hairs in conductive
the inner ear’s cochlea that allow membrane
the brain to recognize electrical implanted inside
pulses as sound are damaged. As a model ear
a step toward an advanced artificial simulates cochlear
cochlea, researchers in ACS Nano hairs by converting
report a conductive membrane, sound waves into
which translated sound waves into electrical pulses;
matching electrical signals when wiring connects
implanted inside a model ear, the prototype to a
without requiring external power. device that collects
the output current
signal. Credit:
When the hair cells inside the
inner ear stop working, there’s Adapted from
no way to reverse the damage. ACS Nano 2021;
Currently, treatment is limited to DOI: 10.1021/
hearing aids or cochlear implants. acsnano.1c04242
But these devices require external
power sources and can have
difficulty amplifying speech
correctly so that it’s understood barium titanate nanoparticles say their self-powered device is
by the user. One possible solution coated with silicon dioxide into a sensitive to the wide acoustic range
is to simulate healthy cochlear conductive polymer, which they needed to hear most sounds and
hairs, converting noise into the dried into a thin, flexible film. Next, voices.
electrical signals processed by they removed the silicon dioxide
the brain as recognizable sounds. shells with an alkaline solution. The authors acknowledge
To accomplish this, previous This step left behind a sponge-like funding from the General
researchers have tried self-powered membrane with spaces around Program of the National
piezoelectric materials, which the nanoparticles, allowing them Natural Science Foundation
become charged when they’re to jostle around when hit by sound of China, the Fundamental
compressed by the pressure waves. In tests, the researchers Research Funds for the Central
that accompanies sound waves, showed that contact between Universities and the Double
and triboelectric materials, the nanoparticles and polymer First-Class-Independent
which produce friction and static increased the membrane’s Innovation-Subject Construction.
electricity when moved by these electrical output by 55% compared
waves. However, the devices to the pristine polymer. When Story Source:
aren’t easy to make and don’t they sandwiched the membrane Materials provided by American
produce enough signal across the between two thin metal grids, the Chemical Society. Note: Content
frequencies involved in human acoustic sensing device produced may be edited for style and length.
speech. So, Yunming Wang and a maximum electrical signal at 170
colleagues wanted a simple way to hertz, a frequency within the range Journal Reference:
fabricate a material that used both of most adult’s voices. Finally, the 1. Jiaqi Zheng, Zhaohan Yu,
compression and friction for an researchers implanted the device Yunming Wang, Yue Fu, Dan
acoustic sensing device with high inside a model ear and played Chen, Huamin Zhou. Acoustic
efficiency and sensitivity across a a music file. They recorded the Core–Shell Resonance Harvester
broad range of audio frequencies. electrical output and converted for Application of Artificial Cochlea
it into a new audio file, which Based on the Piezo-Triboelectric
To create a piezo-triboelectric displayed a strong similarity to the Effect. ACS Nano, 2021; DOI:
material, the researchers mixed original version. The researchers 10.1021/acsnano.1c04242
4 IMMUNOLOGY NEWS
