Tech Briefs Magazine - June 2024 - 27

tional infrastructure that the investment is
not worthwhile, " Donnal added. " Energy-harvesting
systems like this could make
it possible to retrofit a wide variety of diagnostic
sensors on ships and significantly reduce
the overall cost of maintenance. "
In the future, the researchers plan to explore
less energy-intensive means of transmitting
data, such as using optics or acoustics.
They also want to more rigorously
model and predict how much energy
might be coming into a system, or how
much energy a sensor might need to take
measurements, so a device could effectively
gather even more data.
For more information, contact Abby
Abazorius at abbya@mit.edu; 617-2532709.
Low-Voltage,
Low-Power Pressure Sensors for
Monitoring Health
A microstructured hydrogel enables the sensors to obtain higher pressure sensitivity.
Terasaki Institute for Biomedical Innovation, Los Angeles, CA
R
ecent advances in technology have
opened many possibilities for using
wearable and implantable sensors to monitor
various indicators of patient health.
Wearable pressure sensors are de signed
to respond to very small changes in bodily
pressure, so that physical functions such
as pulse rate, blood pressure, breathing
rates, and even subtle changes in vocal
cord vibrations can be monitored in real
time with a high degree of sensitivity.
Such responses occur when a substance
in the sensor " gates, " or allows selected
pressure signals to pass to a transistor,
which then conducts and amplifies
these signals for detection. A recent type
of transistor - organic electrochemical
transistors (OECTs) - has exhibited superior
signal amplification capabilities at
lower voltages and power consumption.
But there has been little exploration of
OECTs for use in pressure sensors because
they are usually paired with liquid
gating substances, which do not respond
well to external pressure.
Researchers found ways to solve this
problem in order to develop soft OECTs
for wearable pressure sensors. They first
experimented with a solid type of gating
substance: a charged, gelatinous substance
called an ionic hydrogel. Due to the physical
characteristics of this gel, they were
successfully able to demonstrate improved
pressure sensing when they used it together
with OECTs.
The team then took this finding a step
further by fabricating ionic hydrogels
with tiny pyramidal microstructures that
helped to increase the pressure sensitivity
that could be measured. The deformity
of the hydrogel microstructures in
response to applied pressure increases
the capacitance change at the gate electrodes,
enhancing the ability to detect
very subtle pressure signals.
The team also found that the microstructured
hydrogel allowed them to
obtain higher pressure sensitivity that
could be adjusted by changing the applied
gate voltage. Furthermore, this
optimized sensor could operate at low
operation voltage and low power consumption.
These features combine to
make a high-performing pressure sensor
that is economical, long-lasting, and
energy-efficient - clear advantages for
devices that are intended to collect longterm,
real-time data.
For more information, contact the Terasaki
Institute at 310-479-6101; https://
terasaki.org/institute/.
The high-performing wearable pressure sensor
is long-lasting and energy-efficient. (Image:
Terasaki Institute)
Tech Briefs, June 2024
www.techbriefs.com
27
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Tech Briefs Magazine - June 2024

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