Tech Briefs Magazine - July 2021 - 46

Health & Biotech
issue but the waves are reflected at interfaces
between different mediums like
hair and skin or bones and other muscle.
Because the magnetic field also transmits
control signals, MagNI is also calibrationfree,
robust, and does not require any
internal voltage or timing reference.
Components of the prototype device
sit on a flexible polyimide substrate with
only three components: a 2 × 4-millimeter
magnetoelectric film that converts
the magnetic field to an electric field, a
CMOS chip, and a capacitor to temporarily
store energy. The team successfully
tested the chip's long-term reliability
by soaking it in a solution and testing
in air and jellylike agar, which emulates
the environment of tissues.
In the current generation of chips,
energy and information flow only one
way but the team is working on two-way
communication strategies to facilitate
data collection from implants and en -
able more applications.
For more information, contact Mike
Williams at mikewilliams@rice.edu; 713348-6728.
Smartphone
App Hears Ear Infections in Children
The app detects fluid behind the eardrum using a piece of paper and a smartphone's
microphone and speaker.
University of Washington, Seattle
E
ar infections occur when fluid builds
up in the middle ear behind the
eardrum and is infected. This buildup is
also common in another condition
called otitis media with effusion. Any
kind of fluid buildup can be painful and
make it hard for children to hear. A new
smartphone app can detect fluid behind
the eardrum by simply using a piece of
paper and a smartphone's microphone
and speaker.
The smartphone makes a series of soft
audible chirps into the ear through a
small paper funnel and depending on
the way the chirps are reflected back to
the phone, the app determines the likelihood
of fluid present with a probability
of detection of 85%. This is on par with
current methods used by specialists to
detect fluid in the middle ear that in -
volve specialized tools that use acoustics
or a puff of air.
The app sends sounds into the ear
and measures how those sound waves
change as they bounce off the eardrum.
The system involves a smartphone and a
regular piece of paper that the doctor
or parent can cut and fold into a funnel.
The funnel rests on the outer ear and
guides sound waves in and out of the ear
canal. When the phone plays a continuous
150-millisecond sound - which
sounds like a bird chirping - through
the funnel, the sound waves bounce off
the eardrum, travel back through the
funnel, and are picked up by the smartphone's
microphone along with the
original chirps. Depending on whether
there's fluid inside, the reflected sound
waves interfere with the original chirp
sound waves differently.
When there is no fluid behind the
eardrum, the eardrum vibrates and sends
a variety of sound waves back. These
46
Cov
The system uses a regular piece of paper cut and folded into a funnel to guide sound waves in and
out of the ear canal. (Dennis Wise/University of Washington)
The app teaches parents how to use it. (Dennis Wise/University of Washington)
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Tech Briefs Magazine - July 2021

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