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WO1997010496A1 - Dispositif de mesure de la concentration d'un gaz en co¿2? - Google Patents

Dispositif de mesure de la concentration d'un gaz en co¿2? Download PDF

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Publication number
WO1997010496A1
WO1997010496A1 PCT/SE1996/001129 SE9601129W WO9710496A1 WO 1997010496 A1 WO1997010496 A1 WO 1997010496A1 SE 9601129 W SE9601129 W SE 9601129W WO 9710496 A1 WO9710496 A1 WO 9710496A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
indicating element
gas
concentration
indicator unit
Prior art date
Application number
PCT/SE1996/001129
Other languages
English (en)
Inventor
Andras Gedeon
Paul Krill
Original Assignee
Icor Instruments Ab
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
Application filed by Icor Instruments Ab filed Critical Icor Instruments Ab
Publication of WO1997010496A1 publication Critical patent/WO1997010496A1/fr

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
    • G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
    • G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
    • G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
    • G01N21/783—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour for analysing gases

Definitions

  • This invention relates to a device for measuring the concen- tration of carbon dioxide, C0 2 , in a gas mixture, especially air and preferably respiratory air, that is, air containing C0 2 in a concentration of about 7 percent or less.
  • the invention relates to a C0 2 measuring device which comprises an indicator unit supporting a C0 2 indicating element whose ability to return incident light is a function of the C0 2 concentration of a gas being in contact with the indicating element, a light source for illuminating the indicating element, and a photoelectric measuring means for measuring the intensity of light returned from the indi ⁇ cating element upon illumination of the indicating element by means of the light source.
  • U.S. Patent No. 3 754 867 A prior art device of this kind is disclosed in U.S. Patent No. 3 754 867.
  • the indicator unit, the light source and the photoelectric measuring means with associated electric components are enclosed in a light-tight box into which the gas mixture to be examined in respect of its C0 2 concentration is fed through an intake opening. It is necessary, therefore, to employ a pump for feeding the gas mixture to the indicator unit. As a result, the device is expensive and cumbersome.
  • the present invention aims at providing a simple and versa ⁇ tile C0 2 measuring device.
  • Fig. 1 is a diagrammatic illustration of a C0 2 measuring device embodying the invention
  • Fig. 2 is an enlarged longitudinal sectional view of a sensor unit which forms part the measuring device shown in Fig. 1;
  • Fig. 3 is a diagram showing the relationship of a photo ⁇ electric detector signal and the C0 2 concentration of a gas mixture being examined;
  • Fig. 4 is a diagrammatic illustration of a curved portion of an optical-fibre cable forming part of the device according to the invention.
  • Main components of the C0 2 measuring device shown in Fig. 2 are a detector unit 11 which includes a current supply 12
  • the detector unit 11 comprises two light sources in the form of light-emitting diodes 18 and 19. These light-emitting diodes emit pulsed light, the pulse frequency being higher than 10 Hz. Preferably, at least one of the light-emitting diodes emits light in the visible range.
  • the light from the light-emitting diodes is fed to the optical-fibre cable 17 of the detector unit through the limbs of a Y-connector 20.
  • the detector unit 11 comprises a photoelectric detector 21 positioned such that it is illuminated by light transmitted through the adjacent end portion 22 of the optical-fibre cable 17 in the direction away from the connector 16 past the Y-connector 20.
  • Detector 21 may be of the wide-band type so as to have substantially the same sensitivity to light over a wide range of wavelengths, but it may also be matched with the wavelengths of the light- emitting diodes.
  • the sensor unit 14 comprises an elongate tubular indicating element holder 23 (indicator unit) which constitutes a female part of a plug-and-socket connector by means of which the optical-fibre cable 15, which comprises a monofilament optical fibre of circular cross-section (such as Super ESKATM, Mitsubishi Rayon Co., Ltd., fibre diameter 1 mm), is separably connected to the detector unit.
  • the optical-fibre cable 15 which comprises a monofilament optical fibre of circular cross-section (such as Super ESKATM, Mitsubishi Rayon Co., Ltd., fibre diameter 1 mm)
  • Extending through the indicating element holder 23 is an axial passage 23A which is widened at the rear end portion of the indicating element holder to form a socket 23B for receiving the male part 24 of the plug-and-socket connector in snap-fit fashion.
  • the optical-fibre cable 15 is secured in an axial passage of the male connector part 24 such that its end portion protru ⁇ des forwardly a short distance beyond the male part .
  • the protruding portion of the optical-fibre cable 15 is received in the front portion of the passage 23A, which is circular in cross-section.
  • the passage 23A is slightly widened in relation to the portion of the passage which receives the forwardly protruding portion of the optical-fibre cable 15.
  • the widened passage portion defines a sensor compartment 25 at the inner end or bottom of which a sheet-like indicating element 26 is positioned which is constructed and arranged such that it forms a substanti- ally gas-tight barrier between the sensor compartment 25 and the portion of the passage 23A which is behind the sensor compartment.
  • the portion of the indicating element holder 23 which protrudes forwardly beyond the indicating element 26 provides mechanical protection for the indicating element.
  • the indicating element 26 is of the known type which contains a dye which changes its optical properties when it is brought in contact with C0 2 . More particularly, the ability of the indicating element to return incident light varies in depend ⁇ ence on the C0 2 concentration of a gas which contacts the indicating element. Characteristic curves for indicating ele- ments of the above-mentioned kind are shown in Fig. 3.
  • the indicating element 26 is comprised of two layers, one transparent, substantially gas-impermeable layer 26A, such as a 0.2 mm polyethylene film, and a layer 26B of paper or other porous material, of 0.1 mm thickness, for example, which is impregnated with the dye.
  • the layer 26A is on the side of the indicating element, the rear side, which faces away from the sensor compartment 25, while the layer 26B is on the opposite side, the front side, and thus is exposed to the gas in the sensor compartment.
  • the side of the layer 26A which faces away from the sensor compartment 25 is coated with a layer 27 (indicated by a heavy solid line) of an optical index-matching or coupling fluid, that is, a substance which has approximately the same refractive index as the material of the optical fibre 15 and which in the illustrated interconnected position of the plug- and-socket connector interconnects the layer 26A and the face of the optical fibre.
  • an optical coupling fluid may be, for example, castor oil or so-called microscope oil.
  • Fig. 3 is a diagram showing characteristic curves for two indicating members 26 chosen by way of example, namely curves showing the relationship between the C0 2 concentration of a gas mixture to which the dyes of the indicating members are exposed and the electric signal provided by the photodetector 21 when the indicating members are illuminated by way of the optical-fibre cable 15.
  • Both indicating members are impregna- ted with the same kind of dye (thymol blue) but the dye con ⁇ centration of the indicating element to which the lower curve A applies is four times that of the indicating element to which the upper curve B applies.
  • the higher dye concentration provides better linearity.
  • the front portion of the indicat- ing element holder 23 is provided with a removable protective cap 28 the front portion of which together with the indicat ⁇ ing element holder forms a compartment 28A which is in open communication with the sensor compartment 25.
  • the pro- tective cap 28 is applied to the indicating element holder 23 during manufacture of the sensor unit 14, the compartments 25 and 28A are filled with pure C0 2 or a gas mixture of a very high C0 2 concentration, far above the limiting concentration. Then the sensor unit 14 formed by the indicating element holder 23 and the protective cap 28 is enclosed in a gas ⁇ tight envelope 29, indicated by a dash-dot line in Fig.
  • the envelope which is preferably filled with pure C0 2 or a gas mixture likewise of a C0 2 concentration far above the limiting con- centration.
  • the envelope may be made from any suitable mate ⁇ rial, such as plastic or metal or metallized foil, that is substantially diffusion-proof so that the envelope will be capable of holding the calibration gas without substantial reduction of the C0 2 content thereof for extended storage periods.
  • the sensor unit 14 formed by the indicating element holder 23 and the protective cap 28 may be used as a disposable item which is thus discarded after a single use.
  • the sensor unit can be manufactured and packaged at low cost and the advantages in respect of hygiene, for example, re ⁇ sulting from one-way use, coupled with the low production cost, means that one-way use is justifiable.
  • the sensor unit may also include the optical-fibre cable 15, and possibly even the optical-fibre cable 17, that is, the entire optical-fibre cable assembly between the indicating element 26 and the detector 21. In the latter case, both optical-fibre cables 15 and 17 may be com ⁇ prised of a single continuous optical fibre.
  • the sensor unit 14 is taken out of the gas-tight package and connected to the flexible optical-fibre cable 15 without re ⁇ moving the protective cap 28.
  • the C0 2 concentration value then obtained is stored by the electronic system of the mea ⁇ suring device. Because of the very high C0 2 concentration in the sensor compartment 25, this measured value corresponds to maximum colour change of the indicating element 26, that is, a maximum photodetector signal .
  • the protective cap 28 is removed so that the indicating element 26 is exposed to ambient air. This means that the indicating element is exposed to air of a very low C0 2 con ⁇ centration, about 0.03 percent.
  • the measured value obtained with this concentration is also stored. Using these two stored measured values and previously stored values repre ⁇ senting the signal-versus-concentration curve of the indi ⁇ cating element being used, the electronic system automati ⁇ cally carries out a calibration of the measuring device.
  • the sensor unit 14, the protective cap 28 having been remo ⁇ ved can then be connected to a device, such as a hose coupling or other connector, which contains or transports the gas to be examined.
  • a device such as a hose coupling or other connector, which contains or transports the gas to be examined.
  • a device such as a hose coupling or other connector
  • connection can be brought about by inserting the narrow front portion of the indicating element holder 23 in a suitably shaped socket in the gas-containing or gas-transporting device.
  • the front portion of the indicating element holder 23 advantageously can be shaped as a standard connector part (Luer fitting) so that it will mate with the fittings which are common in medical apparatus or instruments.
  • the above-described calibration is carried out.
  • the protec- tive cap need not be perfectly tight-fitting. It suffices for it to be able to retain most of the gas in the compartments 25 and 28A for the normally short period from the opening of the envelope to the completion of the first calibration step.
  • the calibration gas in the form of ambient gas which is caused to contact the indicating element 26 in the second calibration step may be supplied otherwise than by removing the protective cap 28 or a similar component from the sensor unit.
  • a seal can be ruptured or a valve can be opened to permit a rapid gas exchange in the space adjoining the indicating element.
  • the above-described calibration procedure in which one first uses a calibrating gas supplied together with and constantly being in contact with the indicating element until a measure ⁇ ment is to be carried out, and whose concentration of the relevant substance is well above the limiting concentration so that the gas provides the same signal regardless of the actual concentration of the substance, and then uses an ambient gas whose concentration of the relevant substance is always the same, is useful also in measuring devices of kinds other than that described above and for substances other than C0 2 , provided that the relationship between the concentration of the substance and the signal representing the concentra ⁇ tion includes a wide range in which the signal may be regar ⁇ ded as independent of the concentration.
  • a substantial improvement of the reproducibility of the mea ⁇ surements carried out using the measuring device according to the invention can be achieved by imposing on at least one section of the optical-fibre cable assembly 15/17 a bend of a permanent or fixed radius curvature which is preferably shorter than the shortest radius of curvature that the flex ⁇ ible portion of the optical-fibre cable is expected to have in use of the measuring device.
  • Such bend should subtend a certain minimum angle, at least 90°, for example, and advantageously subtends a much larger angle, such as a full 360° turn.
  • the radius of curvature and the angle are chosen such that at least 3 and preferably 10 percent of the intensity of a signal of diffuse light fed into the optical-fibre cable will be lost in the bend.
  • the bend in the detector unit 11 or in a housing which enclo- ses the detector unit and the current supply 12 and other "stationary" components of the measuring device.
  • the illustrated embodiment may be modified such that the bend is integrated in the part of the optical-fibre cable assembly which comprises the flexible optical-fibre cable section 15.
  • FIG. 1 A permanent bend comprising a full 360° loop is shown in Fig. 1 and embodied in the optical-fibre cable portion 17 provided in the current supply 12.
  • Fig. 4 is a heavily en ⁇ larged view of a bend subtending only a quarter of a full turn, corresponding to a change of direction of the optical- fibre cable of 90°, and serves to illustrate the function of the bend of the optical-fibre cable section as a kind of fil ⁇ ter which eliminates the disturbances of the light transmis ⁇ sion which would otherwise result from varying bending of the optical-fibre cable during measurements.
  • the flexible optical-fibre cable section 15 which may be several metres long and very flexible, may change its configuration in an indeterminate or random way. In other words, a certain portion of the optical-fibre cable may move in a random way relative to other portions.
  • Light having an angle of incidence close to the critical angle ⁇ G for total reflection is sensitive to a reduction of the curvature of the optical fibre. If the radius of curva ⁇ ture of the optical fibre is reduced locally, light which is totally reflected before it reaches the location where the curvature is reduced may have an angle of incidence at that location which is smaller than the critical angle a G so that the light will be radiated out of the fibre.
  • the above-mentioned intentional and fixed or permanent bend which is provided in the optical-fibre cable and has a radius of curvature smaller than the smallest radius of curvature likely to result from varying bending during use of the measuring device, ensures that substantially all light which enters the optical-fibre cable at an angle which is, so to speak, in the dangerous zone will be caused to leave the fibre through the cladding because the intentional sharp bend makes the angle of incidence of such light fall below the critical angle ⁇ G . Accordingly, only light which enters the optical-fibre cable at an angle sufficiently close to the longitudinal axis of the optical fibre to avoid the dangerous zone will be transmitted the full length of the cable.
  • Fig. 4 shows a 90° bend the ends of which are marked by two orthogonal lines K.
  • Two light rays symbolized by full lines h. represent light having an angle of incidence sufficiently larger than the critical angle ⁇ G so that it will be above the critical angle even in the bend, while a broken-line light ray L 2 represents light whose angle of incidence up- stream of the bend is only slightly larger than the critical angle _ G and in the bend will therefore become smaller than the critical angle _ G so that the light will escape through the cladding surrounding the fibre core.
  • the intentional bend in the optical-fibre cable may be per ⁇ manent in the sense that it cannot be changed or removed without subjecting the optical-fibre cable to substantial external forces. It need not be permanent in that sense, however; within the scope of the invention it may be produced by means of suitable retaining means which clamps or other ⁇ wise stabilizes the optical-fibre cable in a certain curved configuration which may, however, be removed or changed when the clamping or stabilizing effect of the retaining means is eliminated. What is essential is that the intentionally cur- ved optical-fibre cable section does not change its curvature while the measurement is carried out.
  • the radius of curvature and the length of the in ⁇ tentionally curved portion should be chosen so as to elimi- nate a substantial influence on the measuring resulting from such effects as are caused by light the angle of incidence of which is in the sensitive or dangerous zone as explained above.
  • the size of the radius of curvature and the extent of the curved optical-fibre cable portion, as expres- sed in terms of the change of direction of the optical-fibre cable portion between the ends thereof, should be so chosen that a light signal being transmitted through the optical- fibre cable loses at least 3 and preferably 10 percent of its intensity in the bend.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Plasma & Fusion (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth 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 The Use Of Chemical Reactions (AREA)
  • Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

L'invention porte sur un dispositif de mesure de la quantité de CO2 présente dans un mélange de gaz tel que de l'air comportant: une unité indicatrice (23) comportant un élément indicateur de CO2 (26) dont le pouvoir de réflexion de la lumière incidente varie avec la concentration en CO2 du gaz en contact avec l'élément indicateur, une source lumineuse (18, 19) éclairant l'unité indicatrice et un moyen photoélectrique (21) de mesure de l'intensité lumineuse réfléchie par l'unité indicatrice lorsqu'elle est frappée par la lumière. L'unité indicatrice (23) comporte une cavité (23A) recevant l'une des extrémités d'un guide de lumière (15, 17) dont une extrémité est couplée optiquement à l'unité indicatrice (26) et l'autre est couplée optiquement à la source de lumière (18, 19) et aux moyens de mesure (21) de la lumière.
PCT/SE1996/001129 1995-09-11 1996-09-11 Dispositif de mesure de la concentration d'un gaz en co¿2? WO1997010496A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9503139-9 1995-09-11
SE9503139A SE9503139L (sv) 1995-09-11 1995-09-11 Anordning för mätning av CO2 -koncentrationen i en gas

Publications (1)

Publication Number Publication Date
WO1997010496A1 true WO1997010496A1 (fr) 1997-03-20

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PCT/SE1996/001129 WO1997010496A1 (fr) 1995-09-11 1996-09-11 Dispositif de mesure de la concentration d'un gaz en co¿2?
PCT/SE1996/001131 WO1997010497A1 (fr) 1995-09-11 1996-09-11 Dispositif de mesure quantitative d'un gaz constitutif d'un melange gazeux

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Application Number Title Priority Date Filing Date
PCT/SE1996/001131 WO1997010497A1 (fr) 1995-09-11 1996-09-11 Dispositif de mesure quantitative d'un gaz constitutif d'un melange gazeux

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002059254A3 (fr) * 2001-01-09 2004-02-12 Ppg Ind Ohio Inc Procede et dispositif de detection et de controle du taux des contaminants biologiques dans un processus de revetement
US7992561B2 (en) 2006-09-25 2011-08-09 Nellcor Puritan Bennett Llc Carbon dioxide-sensing airway products and technique for using the same
US8396524B2 (en) 2006-09-27 2013-03-12 Covidien Lp Medical sensor and technique for using the same
US8420405B2 (en) 2006-09-25 2013-04-16 Covidien Lp Carbon dioxide detector having borosilicate substrate
US8431088B2 (en) 2006-09-25 2013-04-30 Covidien Lp Carbon dioxide detector having borosilicate substrate
US8431087B2 (en) 2006-09-25 2013-04-30 Covidien Lp Carbon dioxide detector having borosilicate substrate
US8449834B2 (en) 2006-09-25 2013-05-28 Covidien Lp Carbon dioxide detector having borosilicate substrate
CN103180712A (zh) * 2010-09-07 2013-06-26 耐斯特科技有限公司 用于比色管的视觉及电子读取的系统
US11175234B2 (en) 2010-09-07 2021-11-16 Nextteq Llc System for visual and electronic reading of colorimetric tubes

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015009792A1 (fr) 2013-07-16 2015-01-22 Palo Alto Health Sciences, Inc. Procédés et systèmes de capnométrie colorimétrique quantitative

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4697869A (en) * 1985-10-11 1987-10-06 Northern Telecom Limited Attenuator for optical fiber
EP0471861A1 (fr) * 1990-08-13 1992-02-26 Hewlett-Packard GmbH Sonde optique
EP0477501A2 (fr) * 1990-09-24 1992-04-01 Abbott Laboratories Appareil de contrôle en continu d'une pluralité d'analytes chimiques utilisant une fibre optique unique, et procédé de fabrication
EP0550424A2 (fr) * 1992-01-03 1993-07-07 Hewlett-Packard Company Capteur de gaz optique avec polymère pour l'enrichissement de gaz
WO1994010553A1 (fr) * 1992-10-23 1994-05-11 Optex Biomedical, Inc. Sonde a fibres optiques de mesure des parametres d'un fluide

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4697869A (en) * 1985-10-11 1987-10-06 Northern Telecom Limited Attenuator for optical fiber
EP0471861A1 (fr) * 1990-08-13 1992-02-26 Hewlett-Packard GmbH Sonde optique
EP0477501A2 (fr) * 1990-09-24 1992-04-01 Abbott Laboratories Appareil de contrôle en continu d'une pluralité d'analytes chimiques utilisant une fibre optique unique, et procédé de fabrication
EP0550424A2 (fr) * 1992-01-03 1993-07-07 Hewlett-Packard Company Capteur de gaz optique avec polymère pour l'enrichissement de gaz
WO1994010553A1 (fr) * 1992-10-23 1994-05-11 Optex Biomedical, Inc. Sonde a fibres optiques de mesure des parametres d'un fluide

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002059254A3 (fr) * 2001-01-09 2004-02-12 Ppg Ind Ohio Inc Procede et dispositif de detection et de controle du taux des contaminants biologiques dans un processus de revetement
US7992561B2 (en) 2006-09-25 2011-08-09 Nellcor Puritan Bennett Llc Carbon dioxide-sensing airway products and technique for using the same
US8109272B2 (en) 2006-09-25 2012-02-07 Nellcor Puritan Bennett Llc Carbon dioxide-sensing airway products and technique for using the same
US8128574B2 (en) 2006-09-25 2012-03-06 Nellcor Puritan Bennett Llc Carbon dioxide-sensing airway products and technique for using the same
US8420405B2 (en) 2006-09-25 2013-04-16 Covidien Lp Carbon dioxide detector having borosilicate substrate
US8431088B2 (en) 2006-09-25 2013-04-30 Covidien Lp Carbon dioxide detector having borosilicate substrate
US8431087B2 (en) 2006-09-25 2013-04-30 Covidien Lp Carbon dioxide detector having borosilicate substrate
US8449834B2 (en) 2006-09-25 2013-05-28 Covidien Lp Carbon dioxide detector having borosilicate substrate
US8454526B2 (en) 2006-09-25 2013-06-04 Covidien Lp Carbon dioxide-sensing airway products and technique for using the same
US8396524B2 (en) 2006-09-27 2013-03-12 Covidien Lp Medical sensor and technique for using the same
CN103180712A (zh) * 2010-09-07 2013-06-26 耐斯特科技有限公司 用于比色管的视觉及电子读取的系统
US11175234B2 (en) 2010-09-07 2021-11-16 Nextteq Llc System for visual and electronic reading of colorimetric tubes

Also Published As

Publication number Publication date
SE9503139D0 (sv) 1995-09-11
WO1997010497A1 (fr) 1997-03-20
SE9503139L (sv) 1997-03-12

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