Aerospace & Defense Technology - October 2022 - 39

Tech Briefs
Back end
electronics
PPG sensor &
accelerometer
Under the hood
Flex ribbon Cable
Textile integrated oximeter headband sensing device (top). Internal electronics (bottom).
type of the oximeter headband device. Data was collected
from eight test participants in two test scenarios, a functional
evaluation, and a form and fit assessment.
Blood oxygenation (SpO2) is an important metric for monitoring
altitude acclimation, monitoring shock in the event of
trauma or hemorrhage, as well as early detection of viremia.
An individual's SpO2 can drop acutely in response to these
environmental changes, often without warning. In these scenarios,
continuous, real-time monitoring of blood oxygenation
provides the ability for early warning and enables corrective
action to take place prior to more adverse outcomes.
This type of real-time SpO2 monitoring is particularly beneficial
in use cases where a single end-user is monitoring many
individuals, such as a squad medic monitoring their entire
team. However, commercial pulse oximeters currently available
are either tethered to benchtop electronics, limited in
their wear location, or only allow for a single patient or individual
to be monitored by a single device.
Employing finger pulse oximeters or standard adhesive-type
patches is not practical for many field applications because
they interfere with the activities the user must accomplish, or
they are impractical for other varying reasons. Specifically, the
finger-worn SpO2 monitor requires the user to position the
sensor on the finger and remain relatively stationary for the
assessment to take place.
Conversely, there are monitoring systems primarily for use in
the fitness arena that could be acceptable to wear, can be used in
harsh environments, and do not interfere with job performance.
These devices do not provide the accurate and precise physiological
data needed to make mission or safety decisions, however.
For example, the SpO2 monitor on the commercially available
Apple Watch 6 (Apple Inc., Cupertino, CA) requires the user to
remain motionless with their arm in a horizontal position for ten
seconds. This is unacceptable for real-time monitoring of warfighters
while undergoing training or actual missions.
A suitable system must produce valid data, work reliably in
the specific environment for which it is intended, be comfortable
and easy to use, and not inhibit motion or job perforAerospace
& Defense Technology, October 2022
mobilityengineeringtech.com
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mance. Furthermore, sensors must be of minimal
weight and size, consume little power, and have
negligible impact on the body. They must also provide
accurate data that can be analyzed to provide
actionable decision-making. To function in real
time, the wearable SpO2 sensor must have reliable
wireless body area network connections. Without
connectivity, PSM use reverts to physiological data
collection and storage for post hoc analysis.
Recently, a prototype oximeter headband system
was developed to provide real time SpO2 monitoring
for a team of individuals. The purpose of this present
test was to assess the form, fit, and function of the
oximeter headband prototype system. In addition to
the functionality of the developed SpO2 sensor system,
the human factors aspects of the system were
also evaluated. This research documents the first
assessment of the first set of field portable prototypes.
This work was performed by L. E. Cantley, D. C.
Maurer, T. Wang, M. Ibanescu, and W. Tharion for the Massachusetts
Institute of Technology Lincoln Laboratory. For
more information, download the Technical Support Package
(free white paper) at mobilityengineeringtech.com/
tsp under the Sensors category. MIT-0006
http://mobilityengineeringtech.com/tsp http://info.hotims.com/82326-800 http://www.mobilityengineeringtech.com
Aerospace & Defense Technology - October 2022

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