Tech Briefs Magazine - November 2023 - PIT-11

rier wavelengths, with the photoacoustic
process designed to create a consistent ultrasound
source, independent of skin color
or tissue roughness.
The ultrasound echoes returning from
the tissue interior emerge at the skin surface
as localized vibrations, which are measured
by a highly sensitive, specialized laser
Doppler vibrometer.
" With an appropriate laser transmit and
receive implementation, any exposed tissue
surfaces can become viable ultrasound
sources and detectors, " Haupt explains.
Advances Toward a Clinically
Operational System
In 2019, the team demonstrated that
the NCLUS proof-of-concept (GEN-1) system
can acquire ultrasound imagery from
human subjects using skin-safe lasers - a
first in the medical community. However,
the time to acquire the image data from
the patient subject was long and impractical
for clinical practice. In addition, the
GEN-1 system image resolution was significantly
less than that of state-of-the-art medical
ultrasound.
Significant engineering development
has since occurred to transition NCLUS
GEN-1 to an operational system appropriate
for clinical testing. In the clinical
NCLUS system, both the laser source
and receiver are miniaturized and
housed inside an optical head attached
to a portable armature. The lasers that
pulse and scan are 500 times faster than
those of the GEN-1 system, thus reducing
the entire image-data acquisition
time to less than a minute. Future
NCLUS prototypes will involve faster acquisition
times of less than one second.
The new clinical system also operates at
much higher
ultrasound
frequencies
than those of the GEN-1 system, enabling
resolution down to 200 microns,
which is comparable to the resolution of
state-of-the-art medical ultrasound.
The moveable armature enables many
degrees of freedom to view the various
regions of the body. Inside the optical
head are also programmable fast-steering
mirrors that automatically position
the source and receive laser beams to
precisely establish the ultrasound array.
A 2D lidar is used to map the patient's
skin surface topography; a high-framerate
short-wave-infrared (SWIR) camera
records the laser source and receiver
projected locations on the skin, providing
the array parameters necessary for
constructing
ultrasound
images. The
skin-surface topography mapping and laser-position
recordings are registered by
using natural skin features such as freckles.
In this way, a fixed reference frame
is established for performing precise repeat
scans over time.
The NCLUS clinical system generates
fully automated and registered ultrasound
images via synthetic aperture processing.
The team demonstrated this system on a
gel-based puck synthesized to match the
mechanical properties of human tissue
(referred to as a phantom) that control
ultrasound wave propagation.
Through sponsored
programs,
the
team is now developing NCLUS to support
field-forward military applications.
These applications include detecting
and characterizing life-threatening injuries
from internal bleeding in organs;
monitoring debilitating musculoskeletal
injuries and their healing over time; and
providing elastographic imagery of soft
tissue and bone of amputee limb regions
to accelerate the design and fitting of
prosthetic sockets. Civilian applications
include imaging in the intensive care
unit. With NCLUS, emergency medical
technicians, paramedics, and medical
staff without specialized sonography
training might be able to perform ultrasound
imaging outside of a hospital - in
a doctor's office, at home, or in a remote
battlefield setting.
" With further development, NCLUS has
the potential to be a transformative technology:
an automated, portable ultrasound
platform with a fixed-reference-frame capability
similar to that of MRI and CT, "
Samir says.
In the next phase of the NCLUS program,
the team will pursue clinical studies
using an operational skin-safe laser to
evaluate ultrasound images and compare
them to those of conventional medical
ultrasound. If these studies are successful,
the team will seek commercial funding
for clinical medical device development,
followed by U.S. Food and Drug
Administration agency approval.
This article was written by Ariana Tantillo,
Science Writer and Editor, MIT
Lincoln Laboratory. For more information,
contact Ariana, Ariana.Tantillo@
ll.mit.edu
This MEMS Scanning Mirror Could Solve LiDAR's Expensive Autonomous
Vehicle Challenges
L
ight detection and ranging (LiDAR)
provides the type of velocity data about
objects and vehicles that are necessary to
enable the type of decision-making necessary
for navigation systems in autonomous
vehicles. However, most LiDAR sensors
that have been used in automotive and
other mobility applications have been fragile,
expensive and unreliable.
Omnitron Sensors Co-founder and CEO
Eric Aguilar has developed a key component
for LiDARs featured in autonomous
vehicles, based on his experience working
with LiDAR in a variety of past roles with
some of the world's largest technology providers
and manufacturers.
Photonics & Imaging Technology, November 2023
" I first discovered this when I made
the jump from core sensor development
to integrator. Initially, I worked with LiDAR
at Wing, a Google X program for
autonomous delivery drones. At Tesla, I
led the firmware integration team that
took Model 3 from prototype to production.
As I moved on to Argo AI, Ford and
Volkswagen's former robotaxi business, I
continued to grapple with LiDAR-related
issues, " wrote in a May 2023 opinion article
for Electronic Engineering Times,
discussing his experience working with
LiDAR in the past.
Aguilar's company has developed a microelectromechanical
systems (MEMS)
Omnitron Sensors CEO Eric Aguilar.
11
Tech Briefs Magazine - November 2023

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