Tech Briefs Magazine - December 2021 - 34

Communications
Adapter Makes All Headphones Intelligent
" Dumb " headphones are made smart by turning them into sensors.
Rutgers University, Piscataway, New Jersey
ngineers have invented a cheap and
easy way to turn dumb headphones
into smart ones by transforming headphones
into sensors that can be
plugged into smartphones, identify
their users, monitor their heart rates,
and perform other services.
E
The invention, called HeadFi, is
based on a small plug-in headphone
adapter that turns a regular headphone
into a sens ing device. Unlike
smart headphones, regular headphones
lack sensors. HeadFi would
allow users to avoid having to buy a
new pair of smart headphones with
embedded sensors to enjoy sensing
features. HeadFi could turn hundreds of
millions of existing, regular headphones
worldwide into intelligent ones with a
simple upgrade.
Headphones are among the most popular
wearable devices worldwide and they
continue to become more intelligent as
sensor and it works by connecting
headphones to a pairing device such
as a smartphone. It does not require
adding auxiliary sensors and avoids
changes to headphone hardware or
the need to customize headphones,
both of which may increase their
weight and bulk. By plugging into
HeadFi, a converted headphone can
perform sensing tasks and play
music at the same time.
Dumb headphones can be plugged into a HeadFi device
that connects to a cellphone, turning them into intelligent
headphones. Engineers are working on a smaller
version of the device. (Image: Siddharth Rupavatharam)
new functions appear such as touch-based
gesture control. Such functions usually rely
on auxiliary sensors such as accelerometers,
gyroscopes, and microphones that
are available on many smart headphones.
HeadFi turns the two drivers already
inside all headphones into a versatile
The engineers conducted experiments
with 53 volunteers using 54
pairs of headphones with estimated
prices ranging from $2.99 to
$15,000. HeadFi can achieve 97.2
percent to 99.5 percent accuracy on
user identification, 96.8 percent to
99.2 percent on heart rate monitoring,
and 97.7 percent to 99.3 percent on
gesture recognition.
For more information, contact Todd Bates
at todd.bates@rutgers.edu; 848-932-0550.
Thin-Film, High-Frequency Antenna Array for Wireless
Communications
The phased array antenna based on large-area electronics technology could enable many
uses of emerging 5G and 6G wireless networks.
Princeton University, Princeton, New Jersey
esearchers have taken a step toward
developing a type of antenna array
that could coat an airplane's wings, function
as a skin patch transmitting signals to
medical implants, or cover a room as wallpaper
that communicates with In ternet of
Things (IoT) devices.
The technology, which could enable
many uses of emerging 5G and 6G wireless
networks, is based on large-area electronics,
a way of fabricating electronic circuits
on thin, flexible materials. The
approach overcomes limitations of conventional
silicon semiconductors, which
can operate at the high radio frequencies
needed for 5G applications but can only
be made up to a few centimeters wide
and are difficult to assemble into the
R
34
Cov
large arrays required for enhanced communication
with low-power devices.
To achieve these large dimensions,
others have tried discrete integration of
hundreds of little microchips. But that's
not practical - it's not low-cost, reliable,
or scalable on a wireless systems level.
The new technology can natively scale to
large dimensions such as computer monitors
and liquid-crystal display (LCD) televisions.
These use thin-film transistor
technology, which the team adapted for
use in wireless signaling.
The researchers used zinc-oxide thinfilm
transistors to create a 1-foot-long
(30-centimeter) row of three antennas
in a setup known as a phased array.
Phased antenna arrays can transmit narwww.techbriefs.com
ToC
row-beam
signals that can be digitally
programmed to achieve desired frequencies
and directions. Each antenna
in the array emits a signal with a specified
time delay from its neighbors and
the constructive and destructive interference
between these signals adds up
to a focused electromagnetic beam. A
single antenna broadcasts a fixed signal
in all directions; a phased array can
electrically scan the beam to different
directions, enabling point-to-point wireless
communication.
Phased array antennas have been used
for decades in long-distance communication
systems such as radar systems, satellites,
and cellular networks but the new
technology could bring new flexibility to
Tech Briefs, December 2021
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Tech Briefs Magazine - December 2021

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