Tech Briefs Magazine - May 2021 - 30

Sensors
This sensor is useful for items that are
too small to tag individually (e.g., pharmaceutical pills) but there are various
potential applications for the sensor
including use in limit switches, position
sensors, and orientation sensors. The
configuration of the RFID ICs and antenna can be tailored for specific applica-

tions; for example, the system could be
used in a rack-and-pinion gear system to
measure the rotational or angular displacement that arises from a linear force.
Furthermore, the system could be incorporated into a rotary controller to refine
the rotation angle of a rotating system like
a steering system or rotor.

NASA is actively seeking licensees to commercialize this technology. Please contact
NASA's Licensing Concierge at AgencyPatent-Licensing@mail.nasa.gov or call us
at 202-358-7432 to initiate licensing discussions. Follow this link for more information:
https://technology.nasa.gov/patent/MSCTOPS-82.

Carbon-Based Air Quality Sensor
This affordable, scalable sensor could be a vital tool in the fight against air pollution
and its associated health risks.
University of Sussex, United Kingdom

cientists have developed a highly sensitive and accurate nitrogen dioxide
(NO2) sensor that has lifesaving potential applications in domestic, public, and
industrial settings. Long-term exposure
to NO2 - a major air pollutant that originates from combustion engines and
industrial processes - can cause respiratory issues, which can be particularly
severe and even life-threatening for
babies and asthma sufferers. The gas
sensor could provide accurate readings
of NO2 levels in the local environment
in an affordable and portable Internet
of Things device, which could sync with
smartphones and applications.
Monitoring of air quality to prevent
exposure to NO2 at parts-per-billion
(ppb) levels is currently only possible
with unwieldy, expensive equipment
and is therefore scarcely implemented.
The goal of this work was to create a
device that was sensitive and accurate
enough to detect below 20 ppb of NO2

in the air but that would also operate in
real-world situations and be convenient
and affordable enough to have the potential for widespread use.
The breakthrough came when the
team developed an NO2 sensing layer
based on a laser-deposited carbon aerogel (LDCA), which they found to have
ex ceptional selectivity towards NO 2
over other common air pollutants, making it unique amongst carbon nanomaterials. Using a scalable and inexpensive one-step laser process, the thin,
porous, and well-adhered film of LDCA
is deposited onto electrodes, which can
then be housed in a range of device
structures for continuous air monitoring. The sensor is so sensitive that it can
detect close to 10 ppb of NO2 in less
than 15 minutes and crucially, can operate at room temperature - even performing well in humid conditions, a
problematic environment for many
other sensors.

Like condensation on a windowpane,
nanomaterials such as the carbon used in
this development, nearly always have surface water. Normally, this is a negative, as it
interferes with the technology but in this
case, the team was able to use the layer of
water to their advantage to selectively dissolve NO2 instead of other volatiles normally found in ambient conditions.
Potential applications for the sensor
could include as a safety device to monitor the air quality in a baby's bedroom,
to help inform the best walking or
cycling routes and times of day to avoid
high pollution levels, and even by real
estate agents to provide prospective
house buyers with information on the
NO2 levels in a home and area.
The data could also feed into a national or worldwide pollution monitoring
database in order to effect positive action
on air quality.
For more information, contact Anna Ford
at a.ford@sussex.ac.uk; +44 01273 873685.

Passive Polarized Fiber Optic Sensing
This technique has applications in strain, temperature, pressure, vibration, and acoustic sensing.
Langley Research Center, Hampton, Virginia

ptical Frequency Domain Reflectometry (OFDR) fiber optic sensing
is established as highly beneficial for
live, simultaneous, multipoint monitoring in many fields. A critical weakness of
interferometric fiber optic sensing methodologies is that they are susceptible to
errors from external influences that introduce birefringence in polarized laser
light. Currently, this can be mitigated
with active polarization control but the
hardware is costly and requires significantly more components that com-

pound in number and cost as sensor
number increases.
OFDR sensing fibers have many sensing points along their length and can be
configured to simultaneously measure
many things such as distributed strain,
temperature, and chemical presence.
Non-polarized OFDR suffers distortion in
the laser light polarity at connections,
components, bends, and particularly at
locations along sensing fibers where
harsh environmental factors can physically affect the crystal structure of the fiber.

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A new passive polarized fiber optic
sensing system was developed that can
deliver the same results as an active
polarization system with minimal added
hardware expense, regardless of the
sensing capacity. The technology combines optical algorithms and commercially available components to enable
the identification of various polarization states (birefringence) and filters
data for this distortion effect by creating
a sensing system that is 100% polarization diverse. The result is the eliminaTech Briefs, May 2021

https://technology.nasa.gov/patent/MSC-TOPS-82 http://www.techbriefs.com http://www.abpi.net/ntbpdfclicks/l.php?202105TBNAV

Tech Briefs Magazine - May 2021

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