Tech Briefs Magazine - February 2022 - 32

Imaging
Electronic Paper Displays Brilliant Colors
Using ambient light, the reflective screen keeps energy consumption to a minimum.
Chalmers University of Technology, Gothenburg, Sweden
A
new type of reflective screen -
sometimes described as electronic
paper - was developed that offers optimal
color display, while using ambient
light to keep energy consumption to a
minimum.
Traditional digital screens use a backlight
to illuminate the text or images displayed
upon them. This is fine indoors
but creates difficulties in viewing such
screens in bright sunshine. Reflective
screens, however, attempt to use the
ambient light, mimicking the way our
eyes respond to natural paper.
The researchers previously developed
an ultra-thin, flexible material that re -
produces all the colors an LED screen
can display, while requiring only a tenth
of the energy that a standard tablet consumes.
But in the earlier design, the colors
on the reflective screen did not display
with optimal quality. Using a porous
and nanostructured material containing
tungsten trioxide, gold, and platinum,
the team tried a new tactic - inverting
the design in such a way as to allow the
colors to appear much more accurately
on the screen.
The team placed the component that
makes the material electrically conductive
underneath the pixelated nanosA
new design could help produce e-readers, advertising signs, and other digital screens with optimal
color display and low energy consumption. (Photo: Marika Gugole/Chalmers University of Technology)
tructure that reproduces the colors
instead of above it, as was previously the
case. This new design means one looks
directly at the pixelated surface, seeing
the colors much more clearly.
To make these reflective screens, certain
rare metals are required - such as
the gold and platinum - but because
the final product is so thin, the amounts
needed are very small. The researchers
hope that eventually, it will be possible
to significantly reduce the quantities
needed for production.
Reflective screens are already available
in some tablets today but they only
display the colors black and white well,
which limits their use.
In addition to smartphones and
tablets, the technology could also be useful
for outdoor advertising, offering
energy and resource savings compared
with both printed posters or moving digital
screens.
For more information, contact Professor An -
dreas Dahlin at andreas.dahlin@chalmers.se;
+ 46 31 772 28 44.
System Uses Smartphone or Computer Cameras to
Measure Health
The camera captures pulse and respiration signals from a video of a person's face.
University of Washington, Seattle, WA
elehealth has become a critical way
for doctors to still provide health
care while minimizing in-person contact
during COVID-19. But with phone
or online appointments, it's harder for
doctors to get important vital signs
from a patient, such as their pulse or
respiration rate, in real time.
A method uses the camera on a person's
smartphone or computer to take
T
their pulse and respiration signal from
a real-time video of their face. For ma -
chine learning to be helpful in remote
health sensing, the system must identify
the region of interest in a video that
holds the strongest source of physiological
information - such as pulse -
and then measure that over time.
Since every person is different, the system
must quickly adapt to each per32
Cov
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ToC
son's
unique physiological signature
and separate this from other variations
such as what they look like and what
environment they are in.
The team's system is privacy preserving
- it runs on the device instead of in
the cloud - and uses machine learning
to capture subtle changes in how light
reflects off a person's face, which is correlated
with changing blood flow. Then
Tech Briefs, February 2022

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Tech Briefs Magazine - February 2022

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