Tech Briefs Magazine - December 2021 - 32

Imaging
er algorithms to provide 3D images of the
batteries over time.
Solid-state batteries are charged and discharged in custom-made hardware. A smaller, modified version
of the cell shown here was used to image these materials during cycling. (Credit: Matthew McDowell)
Because lithium is so light, imaging it
with X-rays can be challenging and
required a special design of the test battery
cells. The technology used is similar
to what is used for medical computed
tomography (CT) scans. Because of limitations
in the testing, the researchers were
only able to observe the structure of the
batteries through a single cycle. In future
work, they would like to see what happens
over additional cycle and whether the
structure somehow adapts to the creation
and filling of voids. The results would likely
apply to other electrolyte formulations
and the characterization technique could
be used to obtain information about
other battery processes.
Battery packs for electric vehicles must
withstand at least 1,000 cycles during a
projected 150,000-mile lifetime. While
solid-state batteries with lithium metal
electrodes can offer more energy for a
given size battery, that advantage won't
overcome existing technology unless they
can provide comparable lifetimes.
For more information, contact John Toon
at jtoon@gatech.edu; 404-894-6986.
Camera Captures Images of Interior of Solid Objects
The camera combines lasers, computers, and terahertz waves to see " unseen " details.
University of Sussex, Brighton, United Kingdom
team has developed a nonlinear
camera capable of capturing highresolution
images of the interior of solid
objects using terahertz (THz) electromagnetic
waves. Images produced using
THz radiation are called hyperspectral
because the image consists of pixels,
each containing the electromagnetic signature
of the object in that point.
Lying between microwaves and infra -
red in the electromagnetic spectrum,
THz radiation easily penetrates materials
like paper, clothes, and plastic in the
same way X-rays do but without being
harmful. It is safe to use with even the
most delicate biological samples. THz
imaging makes it possible to see the
molecular composition of objects and
distinguish between different materials
such as sugar and cocaine, for example.
The fingerprint of all the details of the
image is preserved in such a way that the
nature of the object can be investigated
in full detail. Until now, cameras capable
of capturing a hyperspectral image pre32
Cov
A
Artistic
rendering of the terahertz field transmitted
by an abstract object.
serving fine details revealed by THz radiation
had not been considered possible.
The team used a single-pixel camera to
image sample objects with patterns of
THz light. The prototype can detect how
the object alters different patterns of THz
light. By combining this information with
the shape of each original pattern, the
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ToC
camera reveals the image of an object as
well as its chemical composition.
Sources of THz radiation are very
faint and hyperspectral imaging had,
until now, limited fidelity. To overcome
this, the team shone a standard laser
onto a unique nonlinear material capable
of converting visible light to THz.
The prototype camera creates THz electromagnetic
waves very close to the sample,
similar to how a microscope works.
As THz waves can travel right through
an object without affecting it, the resulting
images reveal the shape and composition
of objects in three dimensions.
The next phase of research will be in
speeding up the image reconstruction
process and applying THz cameras to realworld
applications such as airport security,
intelligent car sensors, quality control in
manufacturing, and scanners to detect
health problems like skin cancer.
For more information, contact Margaret
Ousby at m.ousby@sussex.ac.uk; (+44) 01273
873685.
Tech Briefs, December 2021

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Tech Briefs Magazine - December 2021

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