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Usually, the arises to measure liquid levels in containers, in large industries; where large volumes of liquids are stored, in small scale industries and residential buildings in developing countries that sees many households implementing their own domestic water supply system. Measurements by humans may be influenced by sentiments, fatigues, lack of concentration, and so on, which has led to economic losses due lost liquid and wasted electric power. Therefore, researches have been directed toward development of automatic liquid level sensing technologies. This paper thus attempts to review available current technologies in automatic liquid level detection systems published in reputable literature. The reviewed technologies are based on optical devices such as light emitting diode (LED), LASER, photocell, photodiode, light dependent resistor (LDR), fibre optics cable and ultrasonic sensors. Other liquid level detection schemes studied are bases on capacitance measurement, edge detection technique in a computer vision system for inspecting the over and under fill liquid level of bottles. This paper also compared the full scale length to resolution ratio of some of the proposals reviewed in a discussion of performance characteristics of liquid level sensors. Finally, evaluated energy cost savings possible when liquid level sensors are used in water pumping systems. This paper will assist instrumentation researchers to know the state of the art in level sensing technology, and practitioners in selecting the right kind of level sensors for a particular application.
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WWJMRD 2017; 3(9): 287-294
International Journal
Peer Reviewed Journal
Refereed Journal
Indexed Journal
UGC Approved Journal
Impact Factor MJIF: 4.25
e-ISSN: 2454-6615
Frederick Ehiagwina
Electrical and Electronics
Engineering, Federal
Polytechnic, Offa, Kwara
State, Nigeria
Lateef Afolabi
Electrical and Electronics
Engineering, Federal
Polytechnic, Offa, Kwara
State, Nigeria
Olufemi Kehinde
Electrical and Electronics
Engineering, Federal
Polytechnic, Offa, Kwara
State, Nigeria
Abdulmutolib Olaoye
Physics Electronics, Federal
Polytechnic, Offa, Kwara
State, Nigeria
Anifowose Jamiu Jibola
Touchpoint Analytics Nigeria
Ltd (MTN Connect Offa),
Kwara State, Nigeria
Frederick Ehiagwina
Electrical and Electronics
Engineering, Federal
Polytechnic, Offa, Kwara
State, Nigeria
Overview of Liquid Level Detection Technologies with
Performance Characteristics Assessment and Energy
Cost Saving for Household Water Pumps
Frederick Ehiagwina, Lateef Afolabi, Olufemi Kehinde, Abdulmutolib
Olaoye, Anifowose Jamiu Jibola
Usually, the arises to measure liquid levels in containers, in large industries; where large volumes of
liquids are stored, in small scale industries and residential buildings in developing countries that sees
many households implementing their own domestic water supply system. Measurements by humans
may be influenced by sentiments, fatigues, lack of concentration, and so on, which has led to
economic losses due lost liquid and wasted electric power. Therefore, researches have been directed
toward development of automatic liquid level sensing technologies. This paper thus attempts to
review available current technologies in automatic liquid level detection systems published in
reputable literature. The reviewed technologies are based on optical devices such as light emitting
diode (LED), LASER, photocell, photodiode, light dependent resistor (LDR), fibre optics cable and
ultrasonic sensors. Other liquid level detection schemes studied are bases on capacitance
measurement, edge detection technique in a computer vision system for inspecting the over and under
fill liquid level of bottles. This paper also compared the full scale length to resolution ratio of some of
the proposals reviewed in a discussion of performance characteristics of liquid level sensors. Finally,
evaluated energy cost savings possible when liquid level sensors are used in water pumping systems.
This paper will assist instrumentation researchers to know the state of the art in level sensing
technology, and practitioners in selecting the right kind of level sensors for a particular application.
Keywords: Capacitance measurement, edge detection, image processing, interferometer, liquid level,
optical fibre, ultrasonic sensors
The need usually arise to measure liquid levels in containers, both in large industries where
large volumes of liquids are stored and in small scale industries, such as the vegetable oil
processing plants, gas service station, and so on. Other areas where there are needs to
measure liquid include public water supplies and treatment plants, fuel depots, even in
residential water supplies. Also breweries and bottling company have critical need for liquid
level sensing so as to maintain standard and minimize economic loss. These liquids may be
inert or highly flammable, conductive or nonconductive[1,2]. Manual or mechanical
measurements may be flawed, due to a multiplicity of factors such as human sentiments,
fatigues, lack of concentration, instrument error and so on. Therefore, researches have been
directed toward development of automatic liquid level sensing technologies.
Meanwhile, Zhou et al.[3] in doing a review of applications of plastic optical fibre (POF)
displacement sensor, highlighted examples and applications of liquid level sensors (LLSs).
However, the review was not comprehensive, since less than 20 literature were reviewed. In
this paper, we reviewed literature discussing liquid level sensing techniques, such as optical,
capacitive and ultrasonic sensors base liquid level technologies. Moreover, technologies
based on edge detection, which is especially useful in bottling companies are highlighted.
The rest of this article is arranged as follows: Section 2 presents a review of fibre optic,
ultrasonic, capacitive and other miscellaneous technologies based systems. Section 3 presents
a comparison of the obtained resolutions of various systems discussed. Finally, Section 4
Wo rld Wide Journa l of Mu ltid iscip linary Re searc h a nd De velo pmen t
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World Wide Journal of Multidisciplinary Research and Development
presents the conclusion are reached and offers
Review of Existing Technologies
There are several approaches reported in the literature for
sensing the level of various kinds of liquid-volatile and
non-volatile, hot or cold, etc. Level sensing technologies
considered in this paper are classified in the taxonomy
shown in fig. 1.
Fig. 1: Taxonomy of liquid detection technology
Optical Sensor Based Technology
Optical devices such as light emitting diodes (LEDs),
LASERs, photocells, photodiodes, and light dependent
resistors (LDRs) have variety of applications in electronic
instrumentations. In addition, optical fibres are useful in
implementing fibre based liquid level sensors, which are
very useful in explosive environment due to their dielectric
and immunity to electromagnetic interference[2]. This
section of the paper examines trendy applications of optical
fibre to liquid level detection.
Birefringence Fibre Loop Mirror and Time Domain
Reflector Based Sensors
Bo et al., in[4], who developed a system with a high
birefringence-fibre loop mirror based on uniform-strength
cantilever beam for liquid sensing. The system applied
force at the end by using a hollow suspending pole. As the
liquid level changes, the applied force varies, which
consequently changes the transmission intensity of the laser
light. Subsequently, the wavelength of the light is used to
evaluate liquid level variations. Manik in[5] used an
optosensor to continuously measure liquid level. Its
approach was to establish an empirical relation for the
attenuation of the light from the light emitting diode (LED)
through a glass tube with varying distance. In its
application to water level sensing, a photo-sensor and a
light reflector in a glass tube floating on the water surface
are used. The intensity of the reflected light detected
depends on the distance between the sensor and the
reflection, which changes with liquid level up to 80 cm to
the nearest 0.5 mm. Additional aspect of this technology
was shown by Yang in[6], who demonstrated a multiplexing
of multiple liquid probes using an optical time domain
reflectometer (OTDR) device for application in liquid level
detection in cryogenic environment. The authors in[7]
reported a system for detecting liquid height in tanks. The
design was based on time-domain reflectometry and it uses
two-wire probe fixed t the wall of the tank- conductive or
nonconductive. Adaptability to container's shape is
enhanced by the use of flexible wire.
Fibre Bragg Grating Based Sensor
A fibre Bragg grating (FBG) liquid sensor based on
bending cantilever beam insensitive to temperature was
demonstrated by Guo, et al. in[8] and, in Sohn and Shim[9].
As the liquid level change, there is a broadening of the
FBG spectrum bandwidth and the consequent, reflection of
optical power. Another FBG based sensor, though
incorporating side- was reported in[10]. However, the FBG
used in this case was polished at the side. It senses level
variation of liquids of arbitrary refractive index, thus
making it more flexible than that reported in[8]. In
addition,[11] demonstrated and test liquid level and
temperature sensor based on tilted fibre Bragg grating. It
was reported that peak amplitude cladding modes and
liquid level are inversely related. Another point to note, is
the simplicity of the design.
Polished and Etched Silica Fibre Based Sensors
The bending losses of a partially polished polymer optical
fibre was harnessed by Montero et al. in[12] in the
development of a self-referencing optical intensity sensor
designed for measuring liquid level in flammable
environment, which is similar to that suggested in[13]. When
a bend on a multimode fiber is incorporated, the higher
order propagating modes in the fiber are refracted because
the angle of incidence increases in the interface core-
cladding, consequently leading to increase of the power
losses in the receiver. The schematic of the scheme
proposed by Montero et al. in[12] is shown in Fig. 2. If the
core refractive index of the fibre, is equal to the cladding
refractive index, it can be considered that the Fresnel
transmission coefficient T, for the beams refracted in an
optical fiber, is given[12] as shown in equation 2:
 
 
4cos cos cos
cos cos cos
 
 
θ = the angle of incidence for a certain beam with the
normal to the core surface
θc = the critical angle, which is the arcsine of the ratio of
cladding refractive index to core refractive index. When θ
is less than or equal to θc, the beam will be refracted from
the fiber core increasing the power losses
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World Wide Journal of Multidisciplinary Research and Development
Fig. 2: Plastic optical fibre sensor arrangement for obtaining liquid level[12]
In addition, Lomer et al.[14] presented a multipoint level
sensor based on lateral polishing bends in U-shapes in POF
with the resultant power loss. The polished bared surface
is in direct contact with the liquid. Consequently, analysis
is done on the variation in optical and geometric parameters
of the multimode POF. Meanwhile, Linesh et al.[15]
proposed a very sensitive level detection technique with a
resolution of 100 mm, it was based on an optical source,
silicon fibres etched with hydrofluoric acid and a detector.
Total Internal Reflection Based Sensing Technique
Furthermore, Li and Yu in[16] developed a system based
frustrated total internal reflection (FTIR) based sensor
combined with single chip computer controlled stepping
motor for tracking and subsequently displaying liquid level.
The sensor head is made from standard multi-mode
communication silica fibre with a tapered tip. Another
FTIR based sensor was reported by Nath, et al., in[17]. The
methodology involved polishing the end face of a step-
index MMF to form a hemispherical tip, which allows part
of the forward propagating modes to be reflected in reverse
direction by the effect of TIR. When the tip of the fibre
touched the liquid, the medium changes, the critical angle
for the back reflected light, thus leading to a modulated
power output. The system is able to detect the level of
chemical liquids such as gasoline, diesel oil, and so on.
Romo-Medrano and Khotiaintsev in[18] used optical sensors
multiplexed using a matrix-type network of optical fibre
using a robust level tracking algorithm for measuring the
liquid level of nitrogen in large cryogenic systems. It
reported a resolution of 5 mm for a full scale measurement
of 1.6 m, which is higher than that reported by Description
of a fibre optic liquid level sensor based on intensity
modulation was presented by Golnabi in[19] and Pérez-
Ocón, et al., in[1]. The methodology used by Golnabi [19]
involves liquid touching the 450 faces of the 45-90-450
prism, leading the total internal reflection (TIR) to be
disturbed and subsequent modulation of the reflected light.
Whereas the approach used[1] involves the principle of TIR
of light with the fibre optic. Power attenuation, which
occurs in the fibre immersed in the liquid container is
measured when there is variation in the liquid level. In
order to minimize error in measurement, the LED light is
modulated before feeding it into the fibre. Pérez-Ocón, et
al. in[1] presented a system shown in fig. 2, and may
incorporate an alarm configurable to alert the observer on
any liquid level in the tank and a means of sending liquid
level data via internet in real time to a distant observer.
Fabry-Perot Fibre and Interferometer Based Sensors
Meanwhile, Lü and Yang in[13] had earlier used an extrinsic
fabry-perot (EFP) cavity comprising of the end of a single-
mode optical fibre and elastic Silicon layer to sense liquid
level. In this approach, liquid pressure change the cavity
length through action on the mechanical construct that
subsequently results in differential phase shifts observable
in the form of signal intensity. The developed system has a
resolution of 10 mm, with a linear range of 1.4 cm. Figure
3 shows the schematic diagram of the intensity based gauge
for liquid level measurement.
Fig. 3: Schematic diagram of the intensity based gauge for liquid
level measurement[1]
Meanwhile, an extrinsic fabry-perot optical fibre
interferometer with an all fused-silica structure and carbon
(IV) oxide laser heating fusion bonding technology, which
can be applied in optical fibre liquid level detection was
reported by Wang and Li in[20]. The developed sensor have
a resolution of 0.7 mm on a full length scale of 5 m, which
is an improved result when compared with the 2 mm
resolution over a range of 3.5 m reported in[13]. Another
fabry-perot cavity structure based system is reported in 21.
It is a white-light interferometric optical fibre sensor. It was
based on sensitivity to pressure, which is a function of
liquid depth. The reported sensitivity of the the system is
830,mmV per 106 N/m2 for up to a pressure of 6×106 N/m2
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World Wide Journal of Multidisciplinary Research and Development
Hence, it is suitable for liquid level detection in
environment containing flammable or explosive substances.
Moreover, in[22], the authors reported a level sensor, which
consists of elliptical multilayer-core fibre having one end
silver coated. Due to the establishment of a Michelson
interferometer, interference shifts related to liquid level can
be observed.
Multimode Interference Effect Based Sensor Furthermore,
Antonio-Lopez, et al., in[24] demonstrated a fibre optic
liquid sensing scheme whose functionality depends on
multimode interference effect. The demonstration involved
fabrication of a single discrete level detection, using a
105/125 step-index multimode fibre, which possesses the
ability of discriminating the refractive index of the liquid
during the level detection. The light source for the system
is tunable laser with wavelength of 1460 to 1580 nm. In
addition, Antonio-Lopez, et al.[23] used the liquid around
the MMF to modify the self-imaging properties of the MMI
device, thus, detecting liquid level. When the effective
refractive index and the diameter of the fundamental mode
of MMF is
, with total length
, then the
free space wavelength is given as equation (1)[23] as:
n d L L
   
   
   
are the effective refractive index of the
section with liquid and the diameter of the fundamental
mode of MMF section with liquid respectively. Figure 4
shows a fibre sensor, with section covered by liquid
other sections not touching the liquid
Fig. 4: Schematic of the fiber-optic liquid level sensor[23]
Ultrasonic Based Technology
The use of ultrasonic to detect liquid level, with LM567 as
the ultrasonic detecting integrated circuit was presented by
Jian-long[25]. The methodology involved measuring the
ultrasonic velocity and the time delay in the detection by
LM567. Later, Ling[26] evaluated several ultrasonic liquid
level measurement methods, pointed out that with
appropriate modification of the ultrasonic speed table, the
liquid level of various liquids at various temperature can be
determined. He went on to develop a system of ultrasonic
liquid level measurement on ektesine of seal vessel.
Gao et al.[27] presented an ultrasonic based liquid level
detection device. The authors further proposed the
observation of weak signals based on chaotic oscillator,
with the aim of enhancing the system's stability against
noise disturbance. Due to the improved accuracy, the
proposed device may be deployed in the measurement of
oil rig. However, Sakharov et al.[28] presented a system
based on ultrasonic lamb waves for the detection of liquid
level in an enclosed metallic tank under high pressure. It is
a non-invasive measurement technique. The developed
system uses two sets of wedge transducer to generate and
receive ultrasonic lamb waves along the circumference of
the tank. Properties of the wave is dependent on the
availability of liquid in the tank, thickness of the wall and
the constituent of the tank wall.
Capacitive Based Technology
Planar Capacitive Sensor
A sensor consisting of planar electrode structure, a
microcontroller and a capacitance controlled oscillator was
presented by Toth, et al.[29]. Resolution of 0.1 mm over 4 m
range within 0.2s was obtained. Reverter and Meijer[30]
developed a remote grounded capacitive sensor. It used a
stainless steel rod and a PTFE-insulated wire. It
incorporated a cable with active shielding to connect the
sensor to an interface circuit which relies on a relaxation
oscillation and a microcontroller. It was used to measure
the level of water in a grounded metallic container with a
resolution of 0.10 mm over a range of 70 cm for a
measuring time of 0.02 s. Ref.[31] uses a mutual calibrated
output function along with taking new fluid as an on-line
reference to develop a multifunctional sensor for
monitoring liquid level and water content of brake fluid
using capacitive method.
Capacitive Glocal Technique
Khan et al.[32] demonstrated the concept of continuous level
monitoring through the development of a capacitive electric
field methods for different fluids. Consequently, finite
element method analysis in the process examining the
sensitivity of the developed sensor in various liquid.
Capacitive Type Differential Sensor
Moreover, a hydrostatic pressure based level detection
device using a very sensitive pulsating capacitive type
differential sensor incorporating a customized oil
manometer aimed at overcoming bubbling effect by air
movements, spurious information of measured level
occasioned by ambient temperature variation, etc. was
presented by Pozo, et al.[33]. Owing to high cost of
commercially available water level sensor and limited
scope of existing system, Loizou and Koutroulis[34]
presented the simulated performance characteristics of a
new capacitive-type water level sensor, comparable to
commercially available ultrasonic based water level
detection schemes, with a much lower cost of production.
Edge Detection Based Technology
Pithadiya, et al.[35] discusses optimal and template based
edge detection technique in a computer vision system for
inspecting the over and underfill liquid level of bottle. It
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World Wide Journal of Multidisciplinary Research and Development
reported that Shen-Castan’s ISEF optimal edge detection
algorithm results were better than results from methods like
Roberts, Prewitt, Sobel, Marr-Hilderth LoG algorithm and
Canny algorithm. Upon review of existing techniques of
bottle inspection in terms of cap closure, overfilling or
under-filling, The authors in [36] proposed a feature
extraction algorithm for achieving the aforementioned three
tasks optimally.
Huang, et al.[37] proposed a system with a field rod for
automatically detecting liquid level in a transparent bottle.
The system, which is based on computer vision,
incorporates positioning techniques used in determining the
rod’s position, which seems broken at the liquid surface
due to the phenomenon of refraction.
Miscellaneous Technologies
Some other techniques are based on acoustic signal
generated by mechanical impact but received by a
piezoelectric polyvinylidene fluoride sensor attached to the
liquid container[38]; PTC thermistor[39]. Meanwhile, a
mmWave radar sensor incorporating stepped frequency
radar methodology operating at 29,720 to 37,700 MHz.
used among other things to observe continuously varying
liquid level in a container[40,41].
Gu et al.[42] presented a system that is sensitive to
microscopic variations in liquid level. The proposed system
was based on near-field microwave microscopy platform
based on an evanescent microwave coaxial probe
electromagnetically coupled with the liquid and Network
analyzer. The electromagnetic coupling was achieved by
means of a tunable broadband matching network placed
between the probe and the test port of the analyzer
operating at about 0.86GHz. An earlier but similar system
based on fibre optic micro displacement sensor was
reported in[43]. Moreover, the authors in[44] demonstrated a
level to frequency converter used for monitoring
intravenous drip liquid level. A merit of this system is its
small dimension, which is 1.96 mm by 2.00mm. This
methodology was different from technique used in[45] for
observing the liquid level in infusion bottle. In addition, the
authors in[46] highlighted some techniques and steps such as
edge detection, binarization, filtering, image projection and
motion detection. In a yet another image processing-based
measure, Wang et al.[47] used a digital camera and a circular
float to observe more precisely and accurately liquid level
in tank using the pixel counts of the uniquely coloured float
in the image captured by the camera and the photographing
Meanwhile, the authors in[48] proposed a contactless liquid
level monitoring device, by measuring the phase shift and
attenuation of the wave reflected from the surface of the
liquid. Due to being contactless, it can be used to detect
level of fluid inside automotive engine. While, the authors
in[49] presented a prototype of a density independent and
non-contact technique for observing liquid level. It was
based on Hough transform and image normalisation. A
merit of this system is that there is no need to recalibrate it,
in detection of the level of different liquid. However
Atojoko et al.[50] uses energy efficient passive UHF RFID
tags as liquid level detectors. The RFID reader is made as
part of the tank in close proximity to the tags. Liquid level
is deduced by observing variation of the tag reading fed to
a computer database. An earlier related work is a low cost
application to restaurant beverage glass as seen in[51]
and[52], where a wireless glassware was developed for
sensing liquid level. Other contactless liquid level sensors
are based on hall effect[53], capacitance measurement[52],
optical effect.[54]
Furthermore, the authors in[55] designed a piezoelectric-
exited millimetre-sized cantilever for sensing liquid level
and subsequently evaluated the dynamic characteristics of
the device for various depth of tip immersion scenarios
using Euler-Bernoulli beam theory. Meanwhile, the device
can observe a level difference of 8um. Furthermore, the
authors in[56] reported a liquid level detection mechanism
that can help in estimating the height of liquid in a blast
furnace hearth. The basis for the system is theoretical hot
metal and slag generation rate observed from both specific
oxygen and calculated drainage rates. Many of the
available methods will fail because of the high temperature
and pressure inside hearth. Liang in[57] worked on fuzzy
PID control for a coupled-tank liquid level control system
having lumping lag and characteristics that are not linear.
Meanwhile, a trend in liquid quantification is the
integration of several sensors in a silicon bases CMOS for
monitoring various parameters of fluid including liquid
Liquid level sensor are instrumentation system so they are
assessed by the following performance characteristics:
reliability, speed of measurement, accuracy, resolution, full
scale range, cost, simplicity of design, and so on. We next
present in Table 1 a discussion of the resolution of some of
the technologies reviewed in this paper.
Table 1: Comparing the resolution of optical and capacitance sensors liquid level detection technology
Full Scale Length (mm)
Resolution (mm)
% resolution (mm) over full scale length
Optical sensor
Optical sensor
Optical sensor
Optical sensor
Capacitive sensor
Capacitive sensor
Optical sensor
Optical sensor
The capacitive sensor based device reported in[29] have a
lower full scale length to resolution ratio of 0.000025. But
Wang and Li[20] reported a scheme with the highest full
scale length of 5 m.
A Case for Applications of Liquid Level Sensor to
Water Pump Control
How to provide and sustain available water resource in
several countries of the World has been a subject of several
discourses. This problem is related to poor water allocation,
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World Wide Journal of Multidisciplinary Research and Development
inefficient use, and lack of adequate and integrated water
management. Therefore, efficient use and water
monitoring, have necessitated research into various water
level sensing technologies, and collection methods. To
prevent or minimize water wastage during pumping and to
care for future need for large volumes of water, the concept
of automatic pumping machine with microcontroller based
water level controller was developed in our previous
work[60] based on the conductivity of a copper wire, as
shown in Fig. 4.
Fig. 4: Hardware prototype of the automatic water level
We show in this section of the paper that energy can be
saved when motorized boreholes pumps in most cities in
Nigeria incorporates liquid level sensor. The quantity of
energy consumed by a water pump is a product of the pump
power rating and the time of operation in pumping up water
to a collection tank. is the number of horse power of
the pump. The quantity of energy (kWh) per minute, of
operation is as shown in equation (2).
At cost of ₦23.5 ($0.0642) per unit (1 kWh), the cost of
energy usage in a minute will be as shown in equation (3).
With the assumption of a household pump up water three
times per week, and the average rating of the pump is 1.5
horse power, Figure 5 shows the cost of energy that could
be save for 1000 motorized pumps, if a water pump is not
allowed to stay ON for an extra minute after the collection
tank is filled to capacity.
Fig. 5: Estimated energy cost savings for incorporating liquid
level detector in boreholes pumps
This paper have shown that liquid level detection
technology have drawn the attention of researchers. In this
regard, trendy technologies are based on the following:
fibre optics sensors, ultrasonic sensors and edge detection.
There are ongoing efforts to improve the accuracy,
resolution and dynamic range of operation of the liquid
level sensor instrumentation. Other efforts are directed
towards development of level sensors that be used in harsh
environment such as the compartment of an internal
combustion engine and the blast furnace of an iron
Cost of energy per household with private borehole based
water scheme would be reduced, if a liquid level detector
based water pump controller is implemented with every
water pump system. In addition, water resource would be
conserved. Meanwhile, much still needed to be done in
terms of integrating liquid level sensors in small scale
liquid storage facilities in developing nations as typified by
Nigeria, where a lot of facilities still rely on deep-sticks and
other crude methods of observing liquid levels.
1. Pérez-Ocón F, Rubiño M, Abril JM, Casanova P,
Martínez JA. Fiber-optic liquid-level continuous
gauge. Sensors Actuators, A Phys. 2006;125(2):124-
132. doi:10.1016/j.sna.2005.07.019.
2. Guo T, Zhao Q, Dou Q, et al. Temperature-insensitive
fiber Bragg grating liquid-level sensor based on
bending cantilever beam. Photonics Technol Lett
IEEE. 2005;17(11):2400-2402.
3. Zhou H, Guang X, Luo D, Sing K, Chong W. A review
of recent developed and applications of plastic fiber
optic displacement sensors. Measurement.
4. Bo D, Qida Z, Feng L, et al. Liquid-level sensor with a
high-birefringence-fiber loop mirror. Appl Opt.
5. Manik NB, Mukherjee SC, Basu AN. Studies on the
propagation of light from a light-emitting diode
through a glass tube and development of an optosensor
for the continuous detection of liquid level. Opt Eng.
6. Yang C, Chen S, Yang G. Fiber optical liquid level
sensor under cryogenic environment. Sensors
Actuators A Phys. 2001;94(1):69-75.
7. Cataldo A, Piuzzi E, De Benedetto E, Cannazza G.
Experimental characterization and performance
evaluation of flexible two-wire probes for TDR
monitoring of liquid level. IEEE Trans Instrum Meas.
8. Guo T, Zhao Q, Dou Q, et al. Temperature-Insensitive
Fiber Bragg Grating Cantilever Beam.
9. Sohn K-R, Shim J-H. Liquid-level monitoring sensor
systems using fiber Bragg grating embedded in
cantilever. Sensors Actuators A Phys.
2009;152(2):248-251. doi:10.1016/j.sna.2009.04.003.
10. Xiaowei D, Ruifeng Z. Detection of liquid-level
variation using a side-polished fiber Bragg grating. Opt
laser Technol. 2010;42(1):214-218.
11. Osuch T, Jurek T, Markowski K, Jędrzejewski K. A
dual-parameter tilted fiber Bragg grating-based sensor
~ 293 ~
World Wide Journal of Multidisciplinary Research and Development
for liquid level and temperature monitoring. In:
Photonics Applications in Astronomy,
Communications, Industry, and High-Energy Physics
Experiments 2016. International Society for Optics and
Photonics; 2016:100311I-100311I.
12. Montero DS, Vázquez C, Möllers I, Arrúe J, Jäger D.
A self-referencing intensity based polymer optical
fiber sensor for liquid detection. Sensors.
2009;9(8):6446-6455. doi:10.3390/s90806446.
13. Lü T, Yang S. Extrinsic Fabry-Perot cavity optical
fiber liquid-level sensor. Appl Opt. 2007;46(18):3682-
14. Lomer M, Arrue J, Jauregui C, Aiestaran P, Zubia J,
López-Higuera JM. Lateral polishing of bends in
plastic optical fibres applied to a multipoint liquid-
level measurement sensor. Sensors Actuators A Phys.
2007;137(1):68-73. doi:10.1016/j.sna.2007.02.043.
15. Linesh J, Sudeesh K, Radhakrishnan P, Nampoori
VPN. Liquid level sensor using etched silica fiber.
Microw Opt Technol Lett. 2010;52(4):883-886.
16. Li GZ, Yu QX. Optical Fiber Frustrated-total-internal-
reflection Based on High Accuracy Liquid Level
Sensor. J Instrum Tech Sens. 2004;2(22).
17. Nath P, Datta P, Ch Sarma K. All fiber‐optic sensor for
liquid level measurement. Microw Opt Technol.
18. Romo-Medrano KE, Khotiaintsev SN. An optical-fibre
refractometric liquid-level sensor for liquid nitrogen.
Meas Sci Technol. 2006;17(5):998.
19. Golnabi H. Design and operation of a fiber optic
sensor for liquid level detection. Opt Lasers Eng.
20. Wang W, Li F. Large-range liquid level sensor based
on an optical fibre extrinsic FabryPerot
interferometer. Opt Lasers Eng. 2014;52:201-205.
21. Zhao J, Xu L, Luo M, Hua J. White-light
interferometric fiber optic liquid sensor based on
MEMS fabry-perot cavity. In: Photonics and
Optoelectronic (SOPO), 2010 Symposium on. IEEE;
2010. doi:10.1109/SOPO.2010.5504424.
22. Liang X, Ren G, Li Y, Liu Z, Wei H, Jian S. In-fiber
liquid-level probe based on Michelson interferometer
via dual-mode elliptical multilayer-core fiber. J Mod
Opt. 2016;63(13):1254-1259.
23. Antonio-Lopez JE, Sanchez-Mondragon JJ, Likamwa
P, May-Arrioja DA. Fiber-optic sensor for liquid level
measurement. Opt Lett. 2011;36(17):3425-3427.
24. Antonio-lopez JE, May-arrioja DA, Likamwa P,
Member S. Fiber-Optic Liquid Level Sensor.
25. Jian-long LEI. Meter Based on Ultrasonic to Measure
the Liquid-level. Instrum Tech Sens. 2004;6(4).
26. Ling HZDWZ. Study on Ultrasonic Liquid Level
Measurement on the Ektexine of Seal Vessel. J
Electron Meas Instrument, 4, 010. 2007;4(10).
27. Gao B, Zhang C, Yang F, Bi H. High accuracy chaotic
oscillators ultrasonic wave liquid level detection. In:
Measurement, Information and Control (MIC), 2012
International Conference on. Vol 2. IEEE; 2012:735-
28. Sakharov VE, Kuznetsov SA, Zaitsev BD, Kuznetsova
IE, Joshi SG. Liquid level sensor using ultrasonic
Lamb waves. Ultrasonics. 2002.
29. Toth FN, Meijer G, van der Lee M. A planar capacitive
precision gauge for liquid-level and leakage detection.
Instrum Meas IEEE Trans. 1997;46(2):644-646.
30. Reverter F, Li X, Meijer GC. Liquid-level
measurement system based on a remote grounded
capacitive sensor. Sensors Actuators A Phys.
31. Wang C, Shida K. A multifunctional self-calibrated
sensor for brake fluid condition monitoring. In: 2006
5th IEEE Conference on Sensors. IEEE; 2006:815-
32. Khan FA, Yousaf A, Reindl LM. Build-up detection
and level monitoring by using capacitive glocal
technique. In: 2016 European Frequency and Time
Forum (EFTF). IEEE; 2016:1-4.
33. Pozo AM, Pérez-Ocón F, Rabaza O. A Continuous
Liquid-Level Sensor for Fuel Tanks Based on Surface
Plasmon Resonance. Sensors. 2016;16(5):724.
34. Loizou K, Koutroulis E. Water level sensing: State of
the art review and performance evaluation of a low-
cost measurement system. Measurement. 2016;89:204-
35. Pithadiya KJ, Modi CK, Chauhan JD. Selecting the
Most Favourable Edge Detection Technique for Liquid
Level Inspection in Bottles. Int J Comput Inf Syst Ind
Manag Appl. 2011.
36. Karasfi B, Hong TS, Jalalian A, Nakhaeinia D.
Speedup Robust Features based unsupervised place
recognition for assistive mobile robot. Pattern Anal
Intell Robot (ICPAIR), 2011 Int Conf. 2011;1:97-102.
37. Huang L, Zhang YL, Hu B, Ma ZM. Automatic
detection of liquid level in transparent bottle based on
machine vision. Zidonghuayu Yibiao/ Autom Instrum.
38. Sanchez-Galicia ER, Stitt EH, Jackson P, York TA.
Acoustic-Based Liquid Level Determination in Process
Vessels using PVDF Sensors. In: 2006 IEEE
Instrumentation and Measurement Technology
Conference Proceedings. IEEE; 2006:1770-1773.
39. Horn M, Umar L, Ruser H. Self-controlled PTC sensor
for reliable overfill protection of liquids. In:
Instrumentation and Measurement Technology
Conference, 2002. IMTC/2002. Proceedings of the
19th IEEE. Vol 1. IEEE; 2002:415-419.
40. Park J, Nguyen C. A Ka-band stepped-frequency radar
sensor for surface and subsurface sensing. In: 2007
IEEE Antennas and Propagation Society International
Symposium. IEEE; 2007:4921-4924.
41. Park J, Nguyen C. Development of a new millimeter-
wave integrated-circuit sensor for surface and
subsurface sensing. IEEE Sens J. 2006;6(3):650-
42. Gu S, Haddadi K, Lasri T. Near-field microwave
microscopy for liquid characterization. In: Microwave
Conference (EuMC), 2014 44th European. IEEE;
43. Sengupta D, Shankar MS, Reddy PS, SaiPrasad RLN,
Narayana KS, Kishore P. A real time fiber optic micro
displacement level sensor. In: Sensing Technology
(ICST), 2011 Fifth International Conference on. IEEE;
44. Chiang C-T, Tsai P-C. A CMOS liquid level to
frequency converter with calibration circuits for
~ 294 ~
World Wide Journal of Multidisciplinary Research and Development
detecting liquid level of intravenous drip. In: 2014
IEEE International Conference on Mechatronics and
Automation. IEEE; 2014:342-346.
45. Zhu H. New algorithm of liquid level of infusion bottle
based on image processing. In: 2009 International
Conference on Information Engineering and Computer
Science. IEEE; 2009:1-4.
46. Pithadiya KJ, Modi CK, Chauhan JD. Comparison of
optimal edge detection algorithms for liquid level
inspection in bottles. In: 2009 Second International
Conference on Emerging Trends in Engineering &
Technology. IEEE; 2009:447-452.
47. Wang T, Lu M, Chen C. Liquid-level measurement
using a single digital camera. 2009;(November 2016).
48. Pelczar C, Meiners M, Gould D, Lang W, Benecke W.
Contactless Liquid Level Sensing using Wave
Damping Phenomena in Free-Space. In:
TRANSDUCERS 2007-2007 International Solid-State
Sensors, Actuators and Microsystems Conference. ;
49. Flores MA, Thome AC, Lima C, Cruz AJ. A dynamic
fluid level monitoring application using Hough
transform and edge enhancement. In: 2009 IEEE
International Symposium on Industrial Electronics.
IEEE; 2009:317-322.
50. Atojoko A, Abd-Alhameed RA, Tu Y, Elmegri F, See
CH, Child MB. Automatic liquid level indication and
control using passive UHF RFID tags. In: Antennas
and Propagation Conference (LAPC), 2014
Loughborough. IEEE; 2014:136-140.
51. Bhattacharyya R, Floerkemeier C, Sarma S. RFID tag
antenna based sensing: Does your beverage glass need
a refill? 2010 IEEE Int Conf RFID (IEEE RFID 2010).
2010:126-133. doi:10.1109/RFID.2010.5467235.
52. Dietz PH, Leigh D, Yerazunis WS. Wireless liquid
level sensing for restaurant applications. Sensors, 2002
Proc IEEE. 2002;1:715-720 vol.1.
53. Pepka G. Position and Level Sensing Using Hall Effect
Sensing Technology. Worcester, Massachusetts; 2007.
54. 54. Reza SA, Riza NA. Author â€TM s personal copy
Agile lensing-based non-contact liquid level optical
sensor for extreme environments.
55. Maroufi M, Shamshirsaz M. Size effect on
performance of Resonant Piezoelectric Millimeter-
sized Cantilevers using as liquid level detection
sensors. Des Test, Integr Packag MEMS/MOEMS
(DTIP), 2012 Symp. 2012:42-46.
56. Agrawal A, Kor SC, Nandy U, Choudhary AR,
Tripathi VR. Real-time blast furnace hearth liquid
level monitoring system. Ironmak Steelmak. 2016:1-9.
57. Liang L. The application of fuzzy PID controller in
coupled-tank liquid-level control system. In:
Electronics, Communications and Control (ICECC),
2011 International Conference on IEEE. ; 2011:2894-
58. Purrington HM, Puchades I, Baylav M, Fuller LF. A
MEMS Universal Fluid Quality Interrogation Sensor.
In: 2010 18th Biennial
University/Government/Industry Micro/Nano
Symposium. ; 2010.
59. Rizvi S, Showan N, Mitchell J. Analyzing the
Integration of Cognitive Radio and Cloud Computing
for Secure Networking. Procedia Comput Sci.
2015;61:206-212. doi:10.1016/j.procs.2015.09.195.
60. Kehinde OO, Bamigboye OO, Ehiagwina FO. Design
and Implementation of an AT89C52 Microcontroller
Based Water Pump Controller. IJISET -International J
Innov Sci Eng Technol Impact Factor. 2016;3(7).
... Due to a variety of circumstances such as human emotions, exhaustion, lack of attention, equipment inaccuracy, and so on, manual or mechanical measurements may be faulty. As a result, efforts have been focused on developing autonomous liquid level detecting technology (Ehiagwina, Afolabi, Kehinde,Olaoye & Jibola, 2017). An important area today where liquid level need to be observed is in automobiles. ...
... In this section of the paper, we focuses on work similar to ours. For an overview of liquid level sensor technologies see Ehiagwina et al. (2017). In Obikoya(2014), the study began with the design and building of a fuel-level sensor, which was followed by the setting of a remote Aplicom 12 global system for mobile communications (GSM) module to connect the sensor. ...
Full-text available
Analogue vehicle fuel gauges have shown obvious inaccuracies providing false impression as to actual fuel level.This research, based on embedded systems, developed a digital display of the exact amount of fuel contained in the fuel tank of the vehicle helps in cross checking the quantity of fuel filled at the petrol station. Whereas, analog fuel meters indicates three states of fuel level which are empty, half and full using needle or meter pointer, the digital fuel meter proposed indicate the amount of fuel in litres. The microcontroller is initia1ized and the fuel level in the tank is measured and LCD displays the fuel amount in the tank.
... Many examples of machine vision-based approaches in food and pharmaceutical industries can be found in [20,21]. However, there are other measurement techniques available like those based on resistive [22], inductive [23], load or pressure sensor [24,25], radar-based [26,27], capacitive [28], piezoelectric [29], ultrasonic [30][31][32], and fiber-optic transducers [33], as well as ones that are being experimentally tested from a scientific point of view like thermal cameras [34]. Many of these techniques have the disadvantage of being intrusive or having a discrete output (e.g., fiber-optic). ...
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Although craft and home brewing have fueled the beer renaissance in the last decade, affordable, reliable, and simple sensing equipment for such breweries is limited. Thus, this manuscript is motivated by the improvement of the bottle-filling process in such settings with the objective of developing a liquid level sensor based on a novel application of the known optical phenomena of light refraction. Based on the different refraction indices of liquid and air (and critical angle based on Snell’s law), along with a novel LED light source positioning, a reliable liquid level sensor system was built with the aid of an embedded microcontroller. The used operating principle is general and can be used in applications other than the proposed one. The proposed method was extensively tested in a laboratory and limited production settings with a speed of 7 Hz using different liquids and container shapes. It was compared for accuracy to other sensing principles such as ultrasound, infrared, and time-of-flight. It demonstrated comparable or better performance with a height error ranging between −0.1534 mm in static conditions and 1.608 mm for realistic dynamic conditions and good repeatability on the production line with a 4.3 mm standard deviation of the mean.
... The available current technologies in automatic liquid level detection systems are based on optical devices such as light emitting diode (LED), LASER, photocell, photodiode, light dependent resistor (LDR), fiber optics cable and ultrasonic sensors. Other liquid level detection schemes are based on capacitance measurement, edge detection technique in a computer vision system for inspecting the over and under fill liquid level of bottles [25]. ...
... Nowadays, liquid level sensing is indeed an active investigation field [1,2]. The need of precise level measurements of liquids mainly arises in industrial environments where large volumes of liquids are stored [3]. ...
This paper shows a new fiber optic sensor multiplexed system for liquid level sensing. Biconical fiber tapers converging at a 40 mm-long micro-fiber are used as transducers. The tapers are designed to provide the propagation of the two main cylindrical modes in the micro-fiber avoiding higher order modes or modes with other symmetries. The liquid level is calculated in real time from the measurement of the frequency and phase components of the spectral interference pattern of the submerged micro-fiber. The system is fully characterized by theoretical simulations in terms of the sensitivity as a function of the most responsive parameter, which is the width of the micro-fiber. Phase sensibilities of 3.7 rad/mm are experimentally obtained and values as high as of the micro-fiber 11.4 rad/mm are theoretically predicted. The strong dependence of the spatial frequency with the width of the micro-fiber has been used to multiplex three sensors in series in this domain. The maximum detected crosstalk between sensors is 0.2 rad/mm.
... Due to the multiplicity of applications, the need arose to construct sensors based on a number of different physical phenomena. Examples of currently used level probes, used both for measurements of liquids and powders are [2][3][4] • Paddle rotary level sensor • Vibrating level sensor • Float sensors • Magnetostrictive sensors • Ultrasonic sensors ...
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The article is about the design and implementation of a laboratory stand for fluxgate liquid level measurement in a tank. It concentrates on the development of the concept and construction of complete measuring device. The new-created mechanical system was analysed to determine the parameters best describing the physical phenomenon occurring, to unambiguously determine the position of the float in relation to the measuring coil, which in turn allows to measure the height of the liquid column in the tank. It also describes the construction of electronic circuits included in the measurement. The analysis of measurement uncertainty of the constructed level meter is also presented.
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serious problem faced by several cities of the World, with wastage during pumping and distribution identified as a culprit. This paper developed a microcontroller based water pump controller aimed reducing water wastages and pump failures, due to not switching it off immediately when not needed. The control system from which water level of both tanks are observed with simultaneous water pump control is based on existing water level technology using the principle of ultrasound for level sensing. A prototype of the proposed microcontroller based water pump controller was fabricated and tested. This paper provided an improvement on existing water level controllers by its use of calibrated circuit to indicate the water level and use of DC instead of ac power, thereby eliminating risk of electrocution. The developed system is capable of powering a 1HP pump from the input voltage, which can deliver an output current up to 20A. The system will help to eliminate the cost and inefficiency of human interference associated with manual monitoring and controlling of pump, while maximizing the performance and life span of the electric water pump.
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A standard problem in large tanks at oil refineries and petrol stations is that water and fuel usually occupy the same tank. This is undesirable and causes problems such as corrosion in the tanks. Normally, the water level in tanks is unknown, with the problems that this entails. We propose herein a method based on surface plasmon resonance (SPR) to detect in real time the interfaces in a tank which can simultaneously contain water, gasoline (or diesel) and air. The plasmonic sensor is composed of a hemispherical glass prism, a magnesium fluoride layer, and a gold layer. We have optimized the structural parameters of the sensor from the theoretical modeling of the reflectance curve. The sensor detects water-fuel and fuel-air interfaces and measures the level of each liquid in real time. This sensor is recommended for inflammable liquids because inside the tank there are no electrical or electronic signals which could cause explosions. The sensor proposed has a sensitivity of between 1.2 and 3.5 RIU(-1) and a resolution of between 5.7 × 10(-4) and 16.5 × 10(-4) RIU.
Full-text available
A stable and efficient blast furnace operation requires proper control of hot metal and slag drainage from the hearth. Many operational problems such as non-dry casts, blow outs, excessive hearth lining wear and low-blast intake arise when the liquid level in the hearth exceeds the critical limit where hearth coke and deadman start to float. Since the direct measurement of the hearth liquid level is practically impossible due to high temperature and pressure inside the furnace, it is therefore important to estimate the liquid level in the hearth and display it to the operators on real-time basis for efficient cast management. This paper presents a system, called hearth liquid level monitoring (LLM), which simulates the liquid level and drainage behaviour of the furnace hearth. It is based on the theoretical hot metal and slag generation rate from the specific oxygen rate and the computed drainage rate from torpedo radar signals and the slag flow measurement system. The system advises the blast furnace operator when to initiate tapping and close the taphole when the liquid level is controlled. It also alerts operators when to use the larger drill bit diameter for opening the next cast.
Full-text available
The focus of this research paper is twofold: First, we discuss some of the critical issues and challenges currently inhibiting the realization of a cognitive radio network (CRN). Those problems include the utilization of jammers to prevent the spectrum sensing and communication. Primary User Emulation (PUE) still pose a significant mitigation challenge, as well as traffic injected attacks. Second, we discuss the possibility of combining the cognitive radios (CRs) within the cloud operating architecture. We present a comprehensive critical analysis of the existing research efforts to integrate these two diverge fields. We identify critical issues and challenges that need to be addressed to successfully integrate the CRs into cloud computing paradigm. In this paper, we also discuss the future scope and directions that need to be taken to maximize the benefits that the venture of these two fields could bring to the service users and providers.
Nowadays, the management of water is of paramount importance for modern societies due to the high water-availability requirements. The application of water management schemes requires the installation of water level data-acquisition systems in multiple, geographically isolated large-scale storage tanks of water distribution networks. Existing techniques for liquid level sensing have either been applied over a relatively small measurement range, or require special scientific equipment of high cost, or they are not convenient for transportation, installation and long-term maintenance in multiple large-scale water storage tanks of water distribution networks in cities, communities etc. In this paper, a review of prior art on liquid level sensing is initially presented. Then, the operational characteristics and performance of a novel capacitive-type water level measurement system are investigated through simulations and experimental tests conducted in two water storage tanks of a city-scale water distribution network. It is demonstrated that the proposed capacitive water level measurement system achieves equivalent performance with that of a commercially-available ultrasound water-level sensing device and simultaneously exhibits a much lower manufacturing cost.
An in-fiber liquid-level probe fabricated from homemade dual-mode elliptical multilayer-core fiber (EMCF) was proposed and experimentally demonstrated. The proposed sensor simply consists of a segment of the EMCF with one end coated with silver film, and a Michelson interferometer is roughly established when light from single-mode fiber incident from the other end. The detected interference patterns, rather clean due to the few-mode property, shift as the liquid level due to strong interaction between high-order modes and measurands through evanescent waves. Both the propagation characteristics and operation principle of such a sensor were demonstrated in detail, and sensitivities of 33.48, 43.35, and 48.93 pm/mm corresponding to liquid indices of 1.333, 1.353, and 1.373 were successfully achieved with a 50-mm EMCF probe, respectively. Moreover, the proposed sensor had the potential to discriminate measurand index after proper calibration.
Conference Paper
This paper proposes a new perspective to the liquid level monitoring and control technique by deploying energy efficient passive UHF RFID tags as liquid level sensors. The system consists of the pump, storage tank, level sensors (passive tags), RFID tag reader, pump control circuit, alarm circuit, and an indicator circuit. The tags are sealed (air and water tight), programmed with unique level labels using the Alien Reader software(860-868MHZ) and deployed to various levels of a storage tank for level monitoring and control. The mirrored P-shaped tag is designed modelled and deployed for use as the liquid level sensors. The RFID reader is disguised to form a part of the tank cover literarily few inches away from the tags. A variation of the tag readings received is used to infer level information which is communicated via the reader middleware to a computer database for monitoring.
Conference Paper
In this paper, a CMOS liquid level to frequency converter with calibration circuits for detecting liquid level of intravenous drip is newly proposed. A calibration technique is proposed in the work. Another innovation is that the outputs of the proposed chip are directly digitized, they could be easily sent over a wide range of transmission media, such as PSN, radio, optical, IR, ultrasonic, and etc. Before performing the proposed calibration circuits, the maximum linear error is 46.44% After calibration, the maximum linear error is reduced to 2.04% The liquid level range is 32 steps, and the corresponding output frequency range is 3.14 to 58.14 kHz. The chip area is 2 × 1.96 mm2. The proposed chip is suitable for devices of measuring liquid level, such as device of detecting liquid level of intravenous drip.
We propose an efficient approach to develop large-range liquid level sensors based on an extrinsic Fabry-Perot optical fibre interferometer with an all fused-silica structure and CO2 laser heating fusion bonding technology. The sensor exhibits signatures of a high sensitivity of 5.3 nm/kPa (36.6 nm/psi), a resolution of 6.8 Pa (9.9×10-4 psi) and an extreme low temperature dependence of 0.013 nm/°C. As a result, a high resolution of the water level measurement of approximately 0.7 mm on the length scale of 5 m and small errors of the water pressure measurement induced by the temperature dependence within 0.0025 kPa/°C (0.00036 psi/°C, water level 0.25 mm/°C) are achieved, thus providing useful applications for the detection of the large-range liquid level in harsh environments.