The Institute - December 2021 - 61

not a physician, wondered whether the
same could be true of COVID-19.
" The signatures would be very
small-at the nanoscale level-but the
changes in the red blood cells would
still be there, " he says.
Javidi's research team decided to
explore digital holographic microscopy,
which is used in cell imaging, cell classification,
and disease identification.
" DHM has drawn great interThe
digital microscope is composed of a laser diode, a microscope objective lens, a
glass plate to induce lateral shearing of the object wavefront, and an image sensor.
Spots Coronavirus
in Blood
Using deep learning, a diagnosis can
be made in a matter of minutes
holography and deep-learning technology
could detect COVID-19 in a drop of
blood. A diagnosis could be made on the
spot in a matter of minutes instead of the
hours or sometimes days it can take for
PCR test results to come back.
The system, which uses digital
holographic microscopy, could be used
in areas that lack health care facilities,
as well as in hospitals whose labs are
backlogged with tests.
That's according to one of the
machine's developers, IEEE Fellow
Bahram Javidi. He is the director of the
Multidimensional Optical Sensing and
Imaging Systems Lab at the University of
Connecticut in Storrs.
The preliminary findings, " Digital
Holographic Deep Learning of Red Blood
Cells for Field-Portable, Rapid COVID-19
Screening, " were published in the Optical
Society's Optics Letters.
The project stemmed from Javidi's
desire to help stop the spread of COVID19
in countries that have limited resources.
" I wanted to find a way to quickly
test for the virus from a droplet of blood
using an affordable, portable, and rapid
disease-identification system, " he says.
The machine uses low-cost components
that can be easily obtained, including
a camera, a laser diode, an objective
lens, a glass plate, and a CMOS image
sensor. The body of the microscope can
be made using a 3-D printer.
Testing a theory
A number of diseases can modify a
person's red blood cells. Javidi, who is
est due to its stain-free operation,
numerical refocusing ability, and
single-shot operation, lending itself
as a powerful tool for biological
sample investigation, " the researchers
wrote in their paper. " The
technology has good vertical resolution-which
helps researchers get
a better sense of the morphology
of cells. And because it relies on
computers for much of the image
processing, it is easy to use. "
The technology has been able to
identify malaria, diabetes, sickle-cell
anemia, and other diseases through
blood samples.
In the team's holographic microscope,
light from the laser diode
passes through the blood sample and
is then magnified by an objective lens.
Part of the light then bounces off the
front of a glass plate and part off the
back, creating two copies of the light
that have passed through the sample.
That creates a hologram that is then
recorded by an image sensor. A technician
is able to computationally work
with the hologram to reconstruct a 3D
profile of the sample.
Individual cells are numerically
reconstructed to retrieve the cells'
phase profile due to the propagation
and interaction of light through
the cells, and then inputted into the
deep-learning network to be classified.
Because no one feature of the
cells was indicative of infection, the
team measured a number of different
features and fed them into the network
to be classified.
Javidi's team worked with doctors at
the university's health center to obtain
the blood samples. He says the next
step is to continue to test blood samples
of COVID-19 patients including from
people outside the United States. He is
looking for collaborators.

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