Microwave and Optical Technology Letters,
Год журнала:
2024,
Номер
66(10)
Опубликована: Окт. 1, 2024
Abstract
The
surveillance
and
assessment
of
the
total
viable
count
(TVC)
Staphylococcus
under
different
levels
catheter
contamination
are
crucial
for
prevention
evaluation
catheter‐related
infections
in
hemodialysis
(HD).
This
paper
demonstrates
noninvasive
accurate
measurement
TVC
using
wavelength‐modulated
tunable
diode
laser
absorption
spectroscopy
(WMAS).
distributed
feedback
with
a
central
wavelength
2004
nm
was
employed
detection
limit
22.5
ppm
carbon
dioxide
(CO
2
)
produced
by
epidermidis
obtained.
growth
medium
concentrations
studied,
results
indicated
strong
correlation
between
rate
final
S.
concentration.
When
degree
low,
resulting
minimal
residual
nutrient
concentration
within
catheter,
bacterial
were
effectively
suppressed.
Therefore,
it
is
proven
that
WMAS
user‐friendly,
noninvasive,
high
signal‐to‐noise
ratio
technique
monitoring
,
making
an
effective
tool
assessing
HD
surveillance.
Microwave and Optical Technology Letters,
Год журнала:
2024,
Номер
66(5)
Опубликована: Май 1, 2024
Abstract
We
propose
a
novel
high‐performance
dual‐resonance
enhanced
photoacoustic
spectroscopy
(DRE‐PAS)
gas
sensor
based
on
highly
sensitive
fiber
optic
cantilever
beam
microphone
and
high‐Q
spherical
cell
(PAC).
The
first‐order
resonant
frequency
(FORF)
of
the
PAC
is
analyzed
by
finite
element
analysis
to
match
FORF
for
double
resonance
enhancement
signal.
(PAS)
system,
including
DRE‐PAS
sensor,
1532.8
nm
distributed
feedback
laser,
high‐speed
spectrometer,
has
been
successfully
exploited
trace
acetylene
(C
2
H
)
detection.
experimental
results
show
that
limit
detection
(LOD)
106.8
parts‐per‐billion
(ppb)
with
an
integral
time
1
s,
LOD
can
be
further
reduced
11.03
ppb
Allan‐Werle
deviation
100
s
time.
normalized
noise
equivalent
absorption
coefficient
obtained
as
2.44
×
10
−8
cm
−1
WHz
−1/2
.
reported
superior
characteristics
signal
enhancement,
high
sensitivity,
strong
antielectromagnetic
interference
capability,
which
provide
new
solution
PAS
development.
Analytical Chemistry,
Год журнала:
2024,
Номер
96(46), С. 18528 - 18536
Опубликована: Ноя. 7, 2024
In
photoacoustic
spectroscopy
based
multicomponent
gas
analysis,
the
overlap
of
absorption
spectra
among
different
gases
can
affect
measurement
accuracy
concentrations.
We
report
a
analysis
method
on
empirical
modal
decomposition
(EMD),
convolutional
neural
networks
(CNN),
and
long
short-term
memory
(LSTM)
that
extract
exact
concentrations
mixed
from
overlapping
wavelength-modulated
with
second
harmonic
(WMS-2f)
detection.
The
WMS-2f
signals
25
concentration
combinations
acetylene-ammonia
mixtures
are
detected
using
single
distributed
feedback
laser
(DFB)
at
1531.5
nm.
acetylene
range
2.5
to
7.5
ppm
ammonia
12.5
37.5
ppm.
data
set
is
enhanced
by
cyclic
shifting
adding
Gaussian
noise.
classification
test
reaches
99.89%
after
tuning.
mean
absolute
errors
five
additional
sets
measured
under
conditions
0.092
for
1.902
ammonia,
within
above
ranges.
Analytical Chemistry,
Год журнала:
2025,
Номер
unknown
Опубликована: Март 31, 2025
Photoacoustic
spectroscopy
(PAS)
gas
sensing
systems
are
generally
classified
into
resonant
and
nonresonant
types.
However,
it
remains
unclear
whether
signals
at
both
frequencies
can
be
demodulated
by
one
demodulation
channel
pass
cell
to
achieve
the
simultaneous
detection
of
two
target
molecules.
In
this
study,
a
cantilever-enhanced
photoacoustic
(PA)
system
was
utilized
measure
H2S
CO2,
which
have
been
identified
as
typical
fault
gases
in
SF6
gas-insulated
electrical
equipment.
The
vibration
modes
cantilever
beam
its
first
were
simulated
analyzed.
Utilizing
laser
interferometer,
measured.
results
confirm
that
components
signal
simultaneously.
Gas
experiments
conducted
using
beam-based
PAS
unit.
Measurements
ternary
mixtures
demonstrated
feasibility
simultaneously
detecting
CO2
extracting
34
349
Hz.
PA
exhibited
strong
linear
relationship
with
concentrations,
limits
2.55
84.69
ppm,
respectively.
Photoacoustics,
Год журнала:
2024,
Номер
38, С. 100626 - 100626
Опубликована: Июнь 12, 2024
Photoacoustic
spectroscopy
(PAS)
has
been
rapidly
developed
and
applied
to
different
detection
scenarios.
The
acoustic
pressure
is
an
important
part
in
the
PAS
system.
In
this
paper,
ultrahigh
sensitivity
Fabry-Perot
sensor
with
a
T-shaped
cantilever
was
proposed.
To
achieve
best
effect,
dimension
of
structure
designed
optimized
by
finite
element
analysis
using
COMSOL
Multiphysics.
Simulation
results
showed
that
such
1.5
times
higher
than
based
on
rectangular
cantilever,
resonance
frequency
were
able
modulate
from
800
Hz
1500
adjusting
multi-parameter
characteristics.
Experimental
sensing
1080
Hz,
yielding
high
1.428
μm/Pa,
signal-to-noise
ratio
(SNR)
84.8
dB
detectable
limit
1.9
μPa/Hz
Microwave and Optical Technology Letters,
Год журнала:
2024,
Номер
66(7)
Опубликована: Июль 1, 2024
Abstract
The
water
vapor
in
the
ambient
air
affects
accuracy
of
photoacoustic
(PA)
dissolved
gas
analysis
system
for
transformer
health
monitoring.
A
laser
PA
was
evaluated
by
dry
and
humidified
standard
gases
to
study
influence
concentration
on
detection.
Theoretical
conducted
effect
molecule
relaxation
signal
high‐frequency
resonant
cell
a
low‐frequency
nonresonant
were
used
detect
acetylene
(C
2
H
)
carbon
monoxide
(CO),
respectively.
experimental
results
show
that
CO
is
about
12
times
higher
than
detection
system,
In
addition,
as
frequency
increased
from
30
980
Hz,
signals
attenuate
1.5
6.9
times,
Photoacoustics,
Год журнала:
2024,
Номер
39, С. 100639 - 100639
Опубликована: Авг. 6, 2024
A
proof-of-concept
on-beam
tuning-fork-enhanced
photoacoustic
sensor
based
on
an
open-closed
single-tube
acoustic-microresonator
(AmR)
was
proposed
and
investigated
for
the
first
time,
to
best
of
our
knowledge.
Due
high
acoustic
amplification
effect,
AmR
improved
detection
sensitivity
by
54
times
with
respect
bare
tuning
fork
(TF).
Compared
traditional
dual-tube/single-tube
spectrophone
configuration,
developed
approach
significantly
facilitates
laser
beam
alignment
reduces
size
gas
consumption.
6.6
kHz
low-frequency
custom
aluminum
alloy
TF
employed
as
transducer
detect
signal.
The
vibration
measured
a
fiber-optic
Fabry-Pérot
(FP)
interferometer
(FPI).
modulation
depth,
tube
length
power
were
experimentally
optimized
evaluated
in
detail.
An
acetylene
(C
