Tech Briefs Magazine - November 2023 - 39

blood, breath, urine, and other biological
samples. It could also be incorporated
into other devices to identify chemicals
in the air or from water, as well as
other surfaces.
The work builds upon previous research
that involved creating a chip that
traps light at the edges of gold and silver
nanoparticles. For the new version, the
team used four molecules (BZT, 4-MBA,
BPT, and TPT) - each with different
lengths - in the fabrication process to
control the size of the gaps in between
the gold and silver nanoparticles. The
updated fabrication process is based
upon two techniques, atomic layer deposition
and self-assembled monolayers, as
opposed to the more common and expensive
method for SERS chips, electron-beam
lithography.
The result is a SERS chip with unprecedented
uniformity that is relatively
inexpensive to produce. More importantly,
it approaches quantum-limit sensing
capabilities.
For more information, contact Cory
Nealon at cmnealon@buffalo.edu; 716645-4614.
An
Ingestible Sensor for Diagnosing
GI Motility Disorders
Such a device could offer an alternative to more invasive
procedures, such as endoscopy, that are currently used to
diagnose gastrointestinal motility disorders.
Massachusetts Institute of Technology, Cambridge, MA, and
California Institute of Technology, Pasadena, CA
E
ngineers at MIT and Caltech have
demonstrated an ingestible sensor
whose location can be monitored as it
moves through the digestive tract, an advance
that could help doctors more easily
diagnose gastrointestinal motility disorders
such as constipation, gastroesophageal
reflux disease, and gastroparesis.
The tiny sensor works by detecting a
magnetic field produced by an electromagnetic
coil located outside the body.
The strength of the field varies with distance
from the coil, so the sensor's position
can be calculated based on its measurement
of the magnetic field.
In the new study, the researchers
showed that they could use this technology
to track the sensor as it moved
through the digestive tract of large animals.
Such a device could offer an alternative
to more invasive procedures, such
as endoscopy, that are currently used to
diagnose motility disorders.
Many people around the world suffer
from GI dysmotility or poor motility, and
having the ability to monitor GI motility
without having to go into a hospital is important
to really understand what is happening
to a patient, " said Giovanni Traverso,
an Associate Professor of
Mechanical Engineering at MIT and a
Gastroenterologist at Brigham and
Women's Hospital.
GI motility disorders, which affect
about 35 million Americans, can occur
Tech Briefs, November 2023
in any part of the digestive tract, resulting
in failure of food to move through
the tract. They are usually diagnosed using
nuclear imaging studies or X-rays, or
by inserting catheters containing pressure
transducers that sense contractions
of the GI tract.
The MIT and Caltech researchers
wanted to come up with an alternative
that would be less invasive and could be
done at the patient's home. Their idea
was to develop a capsule that could be
swallowed and then send out a signal revealing
where it was in the GI tract, allowing
doctors to determine what part of
the tract was causing a slowdown and
better determine how to treat the patient's
condition.
To achieve that, the researchers took
advantage of the fact that the field produced
by an electromagnetic coil becomes
weaker, in a predictable way, as
the distance from the coil increases. The
magnetic sensor they developed, which
is small enough to fit in an ingestible
capsule, measures the surrounding magnetic
field and uses that information to
calculate its distance from a coil located
outside the body.
" Because the magnetic field gradient
uniquely encodes the spatial positions,
these small devices can be designed
in a way that they can sense the
magnetic field at their respective locations, "
Sharma said. " After the device
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Tech Briefs Magazine - November 2023

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