Tech Briefs Magazine - June 2024 - 37

E-Health Patches Monitor Pulse and Blood Pressure
The wireless patches power themselves with harvested energy.
Osaka University, Osaka, Japan
S
cientists at Osaka University, in cooperation
with Joanneum Research (Weiz,
Austria), have introduced wireless health
monitoring patches that use embedded
piezoelectric nanogenerators to power
themselves with harvested biomechanical
energy. This work may lead to new autonomous
health sensors as well as battery-less
wearable electronic devices.
As wearable technology and smart
sensors become increasingly popular,
the problem of providing power to all
of these devices become more relevant.
While the energy requirements of each
component may be modest, the need for
wires or batteries become burdensome
and inconvenient. That is why new energy
harvesting methods are needed. Also,
the ability for integrated health monitors
to use ambient motion to both power
and activate sensors will help accelerate
their adoption in doctor's offices.
Now, an international team of researchers
from Japan and Austria has
invented new ultraflexible patches with
a ferroelectric polymer that can not only
sense a patient's pulse and blood pressure,
but also power themselves from
normal movements. The key was starting
with a substrate just 1-µm thick.
Using a strong electric field, ferroelectric
crystalline domains in a copolymer
were aligned so that the sample
had a large electric dipole moment.
Based on the piezoelectric effect, which
is very efficient in converting natural
motion into small electric voltages, the
device responds rapidly to strain or
pressure changes. These voltages can
be transduced either into signals for
the medical sensors or to directly harvest
the energy.
" Our e-health patches may be employed
as part of screening for lifestyle-related
diseases such as heart
disorders, signs of stress, and sleep apnea, "
said Andreas Petritz, first author
on the paper.
The authors estimate that multilayer
patches can harvest up to 200 mJ per day
from biomechanical motions if placed
on joints, like knees or elbows. This is
Tech Briefs, June 2024
Power generation
device using
ferroelectric polymer
Organic
rectifier
circuit
Energy
strorage
capacitor
Organic
piezoelectric
sensors
Substrate thickness: 1µm
Total thickness
< 2.5 µm
Sheet-type piezoelectric system with self-generation and storage functions. (Image: Osaka University)
1 cm
Accurate biomonitoring is possible without being noticed; the ultrathin and soft sheet system realizes
attachment of the device to the skin. (Image: Osaka University)
enough to monitor cardiovascular parameters
several times a day. And the
patches are so thin that they are barely
perceptible thus making a necessary evil
for many patients - daily health monitoring
- less unpleasant.
" We expect that our findings will assist
in the development of other sheet-type
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sensor systems that can perform precise
biomonitoring when affixed to the skin
surface, " said Tsuyoshi Sekitani, senior
author. Additional modules allow other
features, such as wireless communication
with a smartphone or computer.
For more information, visit https://
resou.osaka-u.ac.jp.
37

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