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WO2012058716A1 - Capteur optique pour mesurer une propriété d'un fluide - Google Patents

Capteur optique pour mesurer une propriété d'un fluide Download PDF

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Publication number
WO2012058716A1
WO2012058716A1 PCT/AU2011/001403 AU2011001403W WO2012058716A1 WO 2012058716 A1 WO2012058716 A1 WO 2012058716A1 AU 2011001403 W AU2011001403 W AU 2011001403W WO 2012058716 A1 WO2012058716 A1 WO 2012058716A1
Authority
WO
WIPO (PCT)
Prior art keywords
sensor
fluid
optical
optical sensor
light
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/AU2011/001403
Other languages
English (en)
Inventor
Kamal Alameh
Linh Nguyen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Edith Cowan University
Original Assignee
Edith Cowan University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2010904881A external-priority patent/AU2010904881A0/en
Application filed by Edith Cowan University filed Critical Edith Cowan University
Publication of WO2012058716A1 publication Critical patent/WO2012058716A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/85—Investigating moving fluids or granular solids
    • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
    • G01N21/45—Refractivity; Phase-affecting properties, e.g. optical path length using interferometric methods; using Schlieren methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/84—Systems specially adapted for particular applications
    • G01N21/85—Investigating moving fluids or granular solids
    • G01N21/8507—Probe photometers, i.e. with optical measuring part dipped into fluid sample
    • G01N2021/8528—Immerged light conductor
    • G01N2021/8542—Immerged light conductor presenting an exposed part of the core
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers

Definitions

  • the present invention relates to an optical sensor for measuring a property of a fluid.
  • the present invention relates to a fibre-optic sensor for measuring a property of a liquid.
  • Optical fibres are of growing interest for sensor
  • Such sensors have the advantage that they usually are very narrow and consequently it is possibly to measure the properties in narrow spaces. Further the sensors usually are inert, which is of further advantage for various applications.
  • An example of an optical fibre sensor is an optical tip sensor, which may include an enclosed air cavity near an end of the optical fibre.
  • the end of the optical fibre is exposed to the liquid and a property of the liquid can be derived from an optical response of the optical fibre sensor.
  • An optical response of the optical tip sensor depends on a refractive index of the liquid, which in turn depends on the density of the substance dissolved in the liquid.
  • the liquid may be water and properties of water, such as temperature or salinity, can be determined using such a sensor.
  • known optical tip sensors have drawbacks. For example, it is not possible to determine two or more
  • an optical sensor for sensing a property of a fluid
  • the optical sensor comprising an optical waveguide, the optical waveguide having a core region and comprising: a sensing region arranged to provide an optical response to guided light, the sensing region comprising a recess extending into at least a part of the core region, the recess having an opening for receiving the fluid and first and second surfaces for reflecting at least a portion of the light, the first and second surfaces being spaced apart from each other by a first distance along the core region, the sensing region further comprising at least one further surface for reflecting at least a portion of the light, the further surface being spaced apart along the core region from the second and first surfaces by a second and third distance, respectively; and
  • the first and second surfaces may be opposing surfaces of a cavity.
  • the further surface may be at an end-face of the optical waveguide.
  • the further surface may also be a surface of a further optical cavity.
  • the first, the second and the third surface have associated optical path lengths and allow the optical sensor to function in a manner similar to that of a three-cavity interferometer. At least two of the surfaces are in use typically in contact with the fluid, thereby allowing the simultaneous measurement of at least two different properties of the fluid, such as properties relating to a composition of the fluid and temperature.
  • the optical sensor may be used for a wide range of
  • the fluid may comprise an aqueous solution or suspension, such as water from lakes, rivers, oceans and water systems in which minerals are suspended and/or
  • the optical sensor may be arranged to measure properties of the water, such as salinity and temperature.
  • the optical sensor typically is arranged such that these properties can be measured simultaneously.
  • the optical sensor may be arranged for in-vivo measurements, such as in-vivo measurements of the human body.
  • the optical sensor may be inserted into a body lumen, such as a blood vessel, and may be arranged to measure properties in the body lumen.
  • the fluid may be blood or another body fluid and the optical sensor may be arranged for simultaneous measurements of two or more properties of the body fluid.
  • At least portions of the optical sensor are in this example typically formed from a bio-compatible material. Further, at least a portion of the sensor may be positioned in a catheter. The possible narrow design of the optical sensor is of particular advantage for in-vivo applications.
  • the fluid may be naturally occurring oil or a product relating to oil, such petrol and the optical sensor may be arranged to measure properties of that fluid.
  • the fluid may also be a gaseous medium, such as natural gas, and the optical sensor may be arranged to measure properties of the gaseous environment.
  • the fluid comprises air and the optical sensor is arranged to measure properties of the air that may characterize an air guality.
  • the first and second distances typically are less than 200ym, less than lOOum or even less than 50um. In one specific example the first and second distances are in the order of tens of micrometers. The first and second distances typically are of the same order of magnitude.
  • the at least one recess may have a stepped profile so as to provide at least one additional reflective surface for that recess . At least one of the surfaces, typically the further surface may be coated with layers of different materials so as to increase the reflectivity of that surface.
  • the optical sensor is or comprises an optical fibre, such as an optical fibre composed of glass or a polymeric material having any suitable outer diameter, such as a diameter of 125 ⁇ or less, ⁇ or less or even less than 50 ⁇ .
  • a sensing system for sensing a property of a fluid comprising:
  • a detector arranged to receive light reflected from the sensor .
  • the sensing system may comprise a plurality of the sensors and an optical switch to which the plurality of sensors are coupled, wherein the optical switch is arranged for directing light to, and receiving light from, the sensors in sequence.
  • a method of sensing a property of a fluid comprising the steps of:
  • the method may comprise determining more than one properties of the fluid.
  • the properties of the fluid may be determined sequentially or substantially simultaneously.
  • Figure 1 is a schematic drawing of a sensor in accordance with an embodiment of the present invention
  • Figure 2 is a flow chart illustrating a method embodiment of the present invention
  • Figure 3 is a schematic drawing of a sensing system
  • Figure 4a is a graph showing a measured reflection spectra of the sensor of Figure 1 immersed in water as the salinity of the water is varied from 0 to 6g in 300mL of pure water (approx. 0 to 20 ppt) at a fixed temperature (20°C );
  • Figure 4b is a graph showing a measured reflection spectra of the sensor of Figure 1 immersed in water as the temperature of the water is varied from 0°C to 50°C at a fixed salinity (pure water) ;
  • Figure 5a is a graph showing measured wavelength shifts of three nearby interference fringes measured by the sensor of Figure 1 immersed in water with respect to water salinity variation at a fixed (room) temperature, wherein an inset of the graph shows the reflection spectra at various water salinity levels;
  • Figure 5b is a graph showing measured wavelength shifts of three interference fringes with respect to ambient
  • Figure 1 shows an optical sensor 10 for sensing a property of a fluid.
  • the sensor 10 comprises an optical waveguide, in this example an optical fibre, having a core region 12, a cladding 14, and a recess 16 located near an end surface 18 of a first end of the sensor 10.
  • the recess 16 defines first and second surfaces 20, 22 with the core region 12 and has an opening for receiving the fluid.
  • Light is directed through the sensor 10 from a second end 24.
  • the surfaces 20, 22 and the end surface 18 provide reflective surfaces for reflecting the light as indicated by double headed arrows of Figure 1.
  • the fluid in the recess 16 typically has a refractive index that is different to that of the core region 12 of the optical fibre and conseguently analysis of the optical response allows identifying these properties.
  • the fluid is water and the sensor is arranged to measure the salinity and temperature of the water.
  • the fluid is a fluid of the human body, such as blood and the optical sensor is arranged for in-vivo measurements.
  • the optical sensor comprises a catheter (not shown) .
  • the optical fibre has a diameter of only 125 ⁇ or less, which makes the optical sensor 10 particularly suitable for in vivo-applications .
  • the fluid may alternatively be of any other suitable type, such as an oil or a gaseous medium and the optical sensor 10 may consequently be arranged for measuring a wide range of properties that affect a refractive index of the fluid.
  • the sensor 10 may comprise any number of recesses.
  • the recess 16 may extend through the entire core region 12, or the recess 16 may have a stepped profile such that a single recess forms more than two surfaces fort reflection within the core region 12.
  • first and second surfaces 20, 22 are spaced apart from each other by a first distance of 74 ⁇ along the core region 12, and the second surface 22 is spaced apart from the end surface 18 by a second distance of 130 ⁇ along the core region 12.
  • a third distance is defined between the first surface 20 and the end surface 18, the third distance being the sum of the first and second distances. This provides three different optical path lengths for light being directed along the sensor 10 and reflected from the surfaces 18, 20, 22.
  • first and second distances may have any appropriate length, such as less than 200 ⁇ or in the order of tens of micrometers. Further, the first and second lengths may be similar.
  • the surfaces 18, 20, 22 are coated with a thin layer of a reflective material so as to increase the reflectivity of the surfaces.
  • the surfaces 18, 20, 22 may be coated with various layers of different materials, such as S1O 2 and T1O 2 , that can be tailored to give optimized reflective properties while the at the same being semi-transmissive for light .
  • Figure 2 shows is a flow chart illustrating a method 25 of sensing a property of a fluid.
  • the method 25 comprises step 26 of providing the sensor 10. Further, the method comprises step 27 of charging the recess 16 of the sensor 10 with the fluid and step 28 of directing light through the sensor 10.
  • the method 10 also comprises step 29 receiving light reflected from the sensor 10 and determining a property of the fluid based on the received reflected light.
  • Figure 3 shows a sensing system 30 for sensing a property of a fluid, in this example water 32 in a container 34.
  • the sensing system 30 is arranged for sensing the salinity and temperature of the water 32.
  • the sensing system 30 comprises a plurality of sensors 10 that are immersed in the water 32 such that the recess 16 of each sensor is immersed in the water 32.
  • the sensing system 30 is configured such that light produced by a light source, such as tunable laser 36, is directed through each sensor 10, and light reflected by the surfaces 18, 20, 22 is received by a photo-detector 38.
  • a light source such as tunable laser 36
  • the laser 36 and the photo-detector 38 are coupled via an optical link
  • circulator 40 for routing the light reflected by each sensor 10 to the photo-detector 38.
  • output from the laser 36 is routed through an optical switch 42 that is arranged to sequentially direct the output from the laser 36 to each sensor 10.
  • the optical switch 42 also functions to sequentially receive reflected light from each sensor 10 and to direct it, via the optical circulator 40, to the photo-detector 38.
  • the laser 36, photo-detector 38 and optical switch 42 are in communication with a data processing unit such as a computer running appropriate software so as to control the laser 36, collect the reflected signals received by the photo-detector 38 and control the optical switch 42.
  • the data processing unit may also be used to process and analyse the received reflected signals so as to determine the spectral response of each sensor 10.
  • the laser 36 is controlled such that its output wavelength is continuously swept over an appropriate
  • bandwidth such as the bandwidth of a typical optical
  • the output of the laser 36 is then directed to each sensor 10 so that a property of the water 32 at each sensor location may be determined.
  • the sensors 10 may be used to determine any appropriate property of the water 32 (or another fluid) , such as flow-rate and tube pressure, and at any number of locations.
  • the interference fringes formed in the spectral domain as a result of the light reflections from the surfaces 18, 20, 22 of the sensor 10, exhibit three distinct groups of response sensitivities with respect to the variations in both the salinity and temperature of the water 32. Therefore, by using a sensitivity matrix calculation method (as described later) , the sensor 10 and sensing system 30 can determine water salinity and ambient temperature simultaneously. As mentioned, the recess 16 is immersed in the water 32 and is therefore filled with the water 32. Light directed through the sensor 10 is therefore subject to properties of the water 32 (and changes thereof) , which influences the reflection coefficients of the surfaces 18, 20, 22 and optical path lengths (i.e. the first, second and third distances) and allows the sensor 10 to function as a three-wave
  • the senor 10 comprises a commercial single-mode optical-fibre and the recess 16 of the sensor 10 was formed near the cleaved end surface 18 using focused ion beam (FIB) milling.
  • FIB focused ion beam
  • An FEI Dual-Beam XL820 system with a Ga liquid-metal ion source was used for micro-machining the recess 16.
  • the accelerating voltage and the ion-beam current used to form the recess 16 were 30kV and 11.5 nA
  • the length of the recess 16, i.e. the first distance between the boundaries 20, 22, is 74 ⁇ and the length of an in-fibre cavity 17 (see Figure 1) i.e. the second distance between the surface 22 and the end surface 18, is 130 ⁇ .
  • the water salinity was varied by gradually dissolving sodium chloride into the surrounding water and the water temperature was changed using a heating plate (not shown) . Assuming a lossless medium for both the recess 16 as well as the in-fibre cavity 17, an approximate value of the
  • normalized total reflection power for the sensor 10 can be derived from:
  • the interference reflection spectra are affected by three cavities formed by different planes which we can denote as recess 16, in-fibre cavity 17, and combined cavity 19 (see Figure 1) which is a combination of recess 16 and in- fibre cavity 17.
  • the optical path lengths of these three cavities 16, 17, 19 vary differently with respect to the environmental changes. In the case of an ascending
  • Combined cavity 19 has a different level of optical path change compared with those of its constituent components .
  • interference pattern on the other hand, is shaped by the reflected optical waves propagating in all three cavities. Therefore, several groups of fringes are present with different sensitivities with respect to variations in both the water salinity and temperature.
  • Figure 4a shows measured reflection spectra of the sensor 10 as the water salinity was varied from 0 to 6g in 300mL of pure water (approx. 0 to 20 ppt) at a fixed temperature (20°C) .
  • Figure 3b shows measured reflection spectra of the sensor 10 as the water temperature was varied from 0°C to 50°C at a fixed salinity (pure water) .
  • Figures 4a and 4b show three distinct groups of response sensitivity with respect to both the water salinity and temperature variations.
  • the fringe visibilities also varied because the refractive index variations affected the
  • the first three fringes (in the measured wavelength range) were located at 1532.65nm,
  • Figure 5a shows the wavelength shifts of interference fringes at 1532.65nm, 1536.76nm and 1540.20nm, respectively, as the salinity was varied from 0 to 60 ppt at (a salinity range that covers most types of saline water) at a fixed
  • Figure 5b shows the wavelength shifts of all fringes with respect to temperature varying from 0°C to 50°C at a fixed salinity.
  • all the fringes exhibited blue-shift and the fringe at 1536.76 nm had the largest temperature-sensitivity while, interestingly, the one at 1540.20 nm had the smallest temperature sensitivity.
  • AS and ⁇ are the water salinity variation and the ambient temperature variation, respectively.
  • A is a
  • sensitivity matrix which takes into account the cross- sensitivity between the water salinity variation and the ambient temperature variation, with the sensitivity
  • invertible e.g. there exists the inverse matrix of A
  • water-salinity variation e.g. there exists the inverse matrix of A
  • the sensitivity matrix A is fairly invertible as its determinant is different from zero for an arbitrary pair of fringes.
  • equation (5), (6) or (7) Using either equation (5), (6) or (7) once the wavelength shifts in [nm] of the fringes were measured experimentally, the water-salinity variation and the ambient temperature variation were obtained separately in [ppt] and [°C], respectively.
  • the normalized root mean square errors of the calculated water salinity and ambient temperature variations were 8.3% and 12% for equation (5), 3.8% and 3% for equation (6), 21% and 18% for equation (7) . Therefore, equation provides the most accurate results for this example.
  • the measurement error can further be minimised by optimising the fringe sensitivity (water salinity and ambient
  • the length of the recess 16 and the length of the in-fibre cavity 17 can be designed so as to provide temperature independent salinity measurements since the respective decrease and increase of the refractive index of the water and silicon as the temperature increases will compensate for one another.
  • the senor 10 can be extended to cover the measurements of one more parameter beside the water salinity and ambient temperature using a [3x3] sensitivity matrix .
  • interrogation of the sensor 10 was carried out with a broadband light source, and the reflected light was analysed using an optical spectrum analyser, as mentioned above.
  • the broadband light source and the optical spectrum analyser can be replaced by a sweeping light source (for example a highly functional tunable laser) and a single photo-detector, as described previously

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

La présente invention porte sur un capteur optique pour détecter une propriété d'un fluide. Le capteur optique comprend un guide d'ondes optique qui a une région de cœur. Le guide d'ondes optique a une région pour guider de la lumière vers et à partir du fluide. Une région de détection est conçue de façon à produire une réponse optique à la lumière guidée. La région de détection a un creux s'étendant dans au moins une partie de la région de cœur. Le creux a une ouverture pour recevoir le fluide et des première et seconde surfaces pour réfléchir au moins une partie de la lumière. Les première et seconde surfaces sont espacées l'une de l'autre d'une première distance le long de la région de cœur. La région de détection comprend de plus au moins une autre surface pour réfléchir au moins une partie de la lumière. L'autre surface est espacée le long de la région de cœur vis-à-vis des seconde et première surfaces d'une deuxième et troisième distances, respectivement.
PCT/AU2011/001403 2010-11-02 2011-11-01 Capteur optique pour mesurer une propriété d'un fluide Ceased WO2012058716A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2010904881A AU2010904881A0 (en) 2010-11-02 An optical sensor for measuring a property of a fluid
AU2010904881 2010-11-02

Publications (1)

Publication Number Publication Date
WO2012058716A1 true WO2012058716A1 (fr) 2012-05-10

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015090359A1 (fr) * 2013-12-17 2015-06-25 Aktiebolaget Skf Capteur à fibre optique pour la surveillance d'un état d'une huile
EP3889580A1 (fr) * 2020-04-05 2021-10-06 TGTW Group B.V. Système et procédé de mesure de contaminants dans un matériau sensiblement translucide, tel que de l'eau

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993013707A1 (fr) * 1992-01-21 1993-07-22 Fiberoptic Sensor Technologies, Inc. Capteur d'oxygenation et de pression sanguine a fibre optique
WO2003054525A2 (fr) * 2001-12-12 2003-07-03 Prolmmune Limited Dispositif et procede d'examen d'analytes en suspension liquide ou en solution
US20050135723A1 (en) * 2003-12-22 2005-06-23 Carr Dustin W. Optical substance analyzer
WO2007102783A1 (fr) * 2006-03-07 2007-09-13 Nanyang Technological University Dispositif de dosage immunologique microfluidique

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993013707A1 (fr) * 1992-01-21 1993-07-22 Fiberoptic Sensor Technologies, Inc. Capteur d'oxygenation et de pression sanguine a fibre optique
WO2003054525A2 (fr) * 2001-12-12 2003-07-03 Prolmmune Limited Dispositif et procede d'examen d'analytes en suspension liquide ou en solution
US20050135723A1 (en) * 2003-12-22 2005-06-23 Carr Dustin W. Optical substance analyzer
WO2007102783A1 (fr) * 2006-03-07 2007-09-13 Nanyang Technological University Dispositif de dosage immunologique microfluidique

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015090359A1 (fr) * 2013-12-17 2015-06-25 Aktiebolaget Skf Capteur à fibre optique pour la surveillance d'un état d'une huile
CN106030263A (zh) * 2013-12-17 2016-10-12 斯凯孚公司 用于油液状态监测的光纤传感器
US9702816B2 (en) 2013-12-17 2017-07-11 Aktiebolaget Skf Optical fiber sensor used for oil conditioning monitoring
CN110715899A (zh) * 2013-12-17 2020-01-21 斯凯孚公司 用于油液状态监测的光纤传感器
EP3889580A1 (fr) * 2020-04-05 2021-10-06 TGTW Group B.V. Système et procédé de mesure de contaminants dans un matériau sensiblement translucide, tel que de l'eau

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