Magnetics Business & Technology - September/October 2022 - 34

VISIONS
UCLA Bioengineers Develop New Class of Human-Powered Bioelectronics
A team of bioengineers at the UCLA Samueli School of Engineering
has invented a novel soft and flexible self-powered
bioelectronic device. The technology converts human body
motions - from bending an elbow to subtle movements such
as a pulse on one's wrist - into electricity that could be used to
power wearable and implantable diagnostic sensors.
The researchers discovered that the magnetoelastic effect,
which is the change of how much a material is magnetized
when tiny magnets are constantly pushed together and pulled
apart by mechanical pressure, can exist in a soft and flexible
system - not just one that is rigid. To prove their concept,
the team used microscopic magnets dispersed in a paperthin
silicone matrix to generate a magnetic field that changes
in strength as the matrix undulated. As the magnetic field's
strength shifts, electricity is generated.
Nature Materials published today a research study detailing the
discovery, the theoretical model behind the breakthrough and
the demonstration. The research is also highlighted by Nature.
" Our finding opens up a new avenue for practical energy, sensing
and therapeutic technologies that are human-body-centric
and can be connected to the Internet of Things, " said Jun
Chen.
" Our finding opens up a new avenue for practical energy, sensing
and therapeutic technologies that are human-body-centric
and can be connected to the Internet of Things, " said study
leader Jun Chen, an assistant professor of bioengineering at
UCLA Samueli. " What makes this technology unique is that
it allows people to stretch and move with comfort when the
device is pressed against human skin, and because it relies on
magnetism rather than electricity, humidity and our own sweat
do not compromise its effectiveness. "
Chen and his team built a small, flexible magnetoelastic generator
(about the size of a U.S. quarter) made of a platinumcatalyzed
silicone polymer matrix and neodymium-iron-boron
nanomagnets. They then affixed it to a subject's elbow with a
soft, stretchy silicone band. The magnetoelastic effect they observed
was four times greater than similarly sized setups with
rigid metal alloys. As a result, the device generated electrical
currents of 4.27 milliamperes per square centimeter, which is
10,000 times better than the next best comparable technology.
In fact, the flexible magnetoelastic generator is so sensitive
that it could convert human pulse waves into electrical signals
and act as a self-powered, waterproof heart-rate monitor. The
electricity generated can also be used to sustainably power
other wearable devices, such as a sweat sensor or a thermometer.
There
have been ongoing efforts to make wearable generators
that harvest energy from human body movements to
power sensors and other devices, but the lack of practicality
has hindered such progress. For example, rigid metal alloys
with magnetoelastic effect do not bend sufficiently to compress
against the skin and generate meaningful levels of power for
viable applications.
Other devices that rely on static electricity tend not to generate
enough energy. Their performance can also suffer in humid
conditions, or when there is sweat on the skin. Some have
tried to encapsulate such devices in order to keep water out,
but that cuts down their effectiveness. The UCLA team's novel
wearable magnetoelastic generators, however, tested well
even after being soaked in artificial perspiration for a week.
A patent on the technology has been filed by the UCLA Technology
Development Group.
UCLA Samueli postdoctoral scholar Yihao Zhou and graduate
student Xun Zhao are co-first authors of the study. They are
both advised by Chen, who directs UCLA's Wearable Bioelectronics
Group and is part of the UCLA Society of Hellman
Fellows. Other authors are UCLA graduate students Jing Xu
and Guorui Chen, postdoctoral scholars Yunsheng Fang and
Yang Song, as well as Song Li - a professor and chair of the
Bioengineering Department.
www.samueli.ucla.edu
https://samueli.ucla.edu/ucla-bioengineers-develop-new-classof-human-powered-bioelectronics/
34
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