Tech Briefs Magazine - February 2022 - 37

cability for wearable biosensors and
general electronic devices, the team
fabricated a self-driven lactate biosensor
that could not only power itself
using lactate and measure the lactate
concentration in sweat, but also communicate
the measured values in real
time to a smartphone via a low-power
Bluetooth device.
Lactate is an important biomarker
that reflects the intensity of physical
exercise in real time, which is relevant in
the training of athletes and rehabilitation
patients. The biofuel cell arrays can
also power other types of wearable electronics.
The team was able to drive a
commercially available activity meter for
1.5 hours using one drop of artificial
sweat and the biofuel cells.
For more information, contact the Media
Office at mediaoffice@admin.tus.ac.jp.
Wearable Device Transforms the Human Body into a
Biological Battery
The device is stretchy enough to wear like a ring, a bracelet, or any other accessory that
touches the skin.
University of Colorado, Boulder, CO
wearable device was developed
that taps into a person's natural
heat, employing thermoelectric generators
to convert the body's internal
temperature into electricity. In the
future, wearable electronics could be
powered without having to include a
battery.
A
The device can generate about 1 volt
of energy for every square centimeter of
skin space - less voltage per area than
what most existing batteries provide but
still enough to power electronics like
watches or fitness trackers.
The thermoelectric wearable device can
heal itself when damaged and is fully recyclable,
making it a cleaner alternative to
traditional electronics. It consists of a base
made out of a stretchy material called polyimine.
The team then sticks a series of thin
thermoelectric chips into that base, connecting
them all with liquid metal wires.
The final product looks like a cross
between a plastic bracelet and a miniature
A thermoelectric wearable device worn as a ring. (Photo: Xiao Lab)
computer motherboard. The design
makes the system stretchable without
introducing much strain to the thermoelectric
material, which can be very brittle.
As the wearer exercises and the body
heats up, the heat radiates out to the
cool outside air. The wearable device
captures that flow of energy rather than
letting it go to waste. The team calculated
that a person taking a brisk walk
could use a device the size of a typical
sports wristband to generate about 5
volts of electricity, which is more than
what many watch batteries can muster.
The device is as resilient as biological tissue.
If the device tears, for example, the
broken ends can be pinched and they will
seal back up in a few minutes. When done
with the device, it can be dunked into a
special solution that will separate out the
electronic components and dissolve the
polyimine base - each one of those ingredients
can then be reused.
For more information, contact Daniel Strain
at daniel.strain@colorado.edu; 303-735-5875.
Polymer-Based Battery Enables Fast Charging and Low
Operating Temperatures
The battery charges faster than a lithium-ion battery and is fire-safe and eco-friendly.
St. Petersburg State University, St. Petersburg, Russia
ithium-ion (Li-ion) batteries are
used in everything from smartphones
to electric vehicles. At the same
time, Li-ion batteries also have a number
of serious disadvantages. Among
them are possible fire risk and loss of
capacity in the cold as well as posing a
significant threat to the environment
when disposed of.
L
Tech Briefs, February 2022
Cov
Chemists are considering redox-active
nitroxyl-containing polymers as materials
that could become the basis for new batteries.
They are characterized by a high
energy density (amount of energy per
unit volume) and speed of charging and
discharging as a result of redox reactions.
The use of such polymers is hampered
by their insufficient electrical conwww.techbriefs.com
ToC
ductivity,
which prevents the accumulation
of charge even when using additives
with high conductivity, such as coal.
To solve this problem, a team of
researchers synthesized a polymer based
on the nickel-salen complex (NiSalen).
The molecules of this polymer act as a
molecular wire on which energy-intensive
nitroxyl fragments are attached. The
37

http://www.techbriefs.com http://info.hotims.com/82318-800

Tech Briefs Magazine - February 2022

Table of Contents for the Digital Edition of Tech Briefs Magazine - February 2022