WO2004023113A1 - Gas sensors - Google Patents

Gas sensors Download PDF

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Publication number
WO2004023113A1
WO2004023113A1 PCT/GB2003/003782 GB0303782W WO2004023113A1 WO 2004023113 A1 WO2004023113 A1 WO 2004023113A1 GB 0303782 W GB0303782 W GB 0303782W WO 2004023113 A1 WO2004023113 A1 WO 2004023113A1
Authority
WO
WIPO (PCT)
Prior art keywords
gas
sensor
gas sensor
source
detector
Prior art date
Application number
PCT/GB2003/003782
Other languages
French (fr)
Inventor
Graham Paul Hopkins
Original Assignee
E2V Technologies (Uk) Limited
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 E2V Technologies (Uk) Limited filed Critical E2V Technologies (Uk) Limited
Priority to AU2003260767A priority Critical patent/AU2003260767A1/en
Publication of WO2004023113A1 publication Critical patent/WO2004023113A1/en

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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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03—Cuvette constructions
    • 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
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/0004—Gaseous mixtures, e.g. polluted air
    • G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
    • G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
    • G01N33/0036—Specially adapted to detect a particular component
    • G01N33/004—Specially adapted to detect a particular component for CO, CO2
    • 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
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G01N21/03—Cuvette constructions
    • G01N2021/0385—Diffusing membrane; Semipermeable membrane
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/02—Mechanical
    • G01N2201/022—Casings
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2201/00—Features of devices classified in G01N21/00
    • G01N2201/12—Circuits of general importance; Signal processing
    • G01N2201/121—Correction signals
    • G01N2201/1211—Correction signals for temperature

Definitions

  • This invention relates to apparatus for, and methods of, sensing gasses .
  • the invention particularly relates to such methods and devices in which optical radiation is transmitted through a gas and subsequently detected to provide information concerning the gas .
  • an infrared source is arranged to emit radiation, which passes through a gas to be monitored. Infrared radiation is absorbed by the gas and that remaining is subsequently detected by an infrared detector. A comparison is made between the source intensity and the intensity of radiation detected following passage through the gas to give the concentration of a target gas .
  • the present invention seeks to provide a gas sensing device, which although manufactured economically from a minimal number of inexpensive components, performs its function as well as more sophisticated sensors.
  • the invention provides a gas sensor comprising an optical source and detector means sensitive to light from the source, the source and detector being electrically connected to a circuit board which forms part of a housing for the source and detector, and the sensor further comprising means arranged, in use, to admit gas into the housing.
  • the means for admitting gas into the housing comprises apertures in the housing, which apertures may be formed in the circuit board.
  • part of the housing may comprise sintered material to admit gas to the sensor.
  • the gas sensor further includes a temperature sensor arranged to detect temperature inside the housing.
  • the output from the temperature sensor may be input to a control system arranged to provide a signal to compensate for changes in the sensor output with ambient temperature .
  • the invention lends itself to the monitoring of carbon dioxide levels at and above critical and is therefore suitable for the detection of the presence of humans or animals in an enclosed environment . Therefore, the invention may be employed in a variety of security and rescue applications .
  • Figure 1 is a sectional view of a gas sensor constructed according to
  • Figure 2 is a sectional view of an alternative gas sensor constructed
  • FIG. 3 is a sectional view of another alternative gas sensor constructed according to the invention.
  • Figure 4 is a sectional view of a further alternative gas sensor constructed according to the invention
  • Figure 5 is a sectional view of a further alternative gas sensor constructed according to the invention
  • Figure 6 is a sectional view of a further alternative gas sensor constructed according to the invention.
  • Figures 7a and 7b are cross sectional views of channels suitable for inclusion in the sensor of Figure 6.
  • the gas sensor 1 comprises a source 2 of infrared (IR) radiation, electrically connected to, and physically mounted on, a printed circuit board (PCB) 3.
  • the sensor 1 further comprises an infrared detector 4, which includes a bandpass filter.
  • the detector 4 is also electrically connected to, and physically mounted on, the PCB 3. Suitable detectors include photodiodes, thermopiles and pyroelectric devices .
  • a cover 5 is provided for the source 2 and detector 4.
  • the cover 5, together with the PCB 3 forms a housing 6 for the components of the sensor 1.
  • the interior surfaces of the housing 6 form an optical cavity.
  • the interior surfaces of the cover are coated with a metallic layer, for example gold. Any material that is highly reflective to IR radiation may be employed.
  • the surface of the PCB onto which the components are mounted may also be coated with IR reflective material .
  • the cover 5 has a tapered wall 7 with a curved end portion 8 arranged so that, in the sectional view of Figure 1, the cover 5 resembles the shape of a thimble.
  • at least a portion of the cover 5 comprises a sinter, to allow gas to be admitted into the housing 6 by diffusion.
  • the source 2 produces broadband IR radiation, which is reflected by the surfaces of the cavity and absorbed by the gas in the housing to a degree proportional to the amount of gas present.
  • a range of wavelengths of the broadband IR radiation not absorbed by the gas is detected at the detector 4.
  • the detector 4 generates an electrical signal corresponding to the strength of the detected IR radiation. This signal is input to processing electronics (not shown) arranged to ) determine the concentration of gas present in the housing.
  • the concentration is related to the intensity by the following equation:
  • I is the intensity of radiation detected by the detector
  • 10 is the intensity of radiation emitted at the source
  • e is effectively a constant which is dependent on the particular gas being monitored
  • c is the gas concentration
  • I is the distance travelled by the radiation through the gas.
  • the sensor and processing electronics may be configured to detect an increase or decrease ( ⁇ c) in concentration of the gas being sensed. Alternatively, absolute measurements of the concentration of a particular gas may be determined.
  • the cover 9 comprises a solid shell of pressed metal . Gas is able to diffuse into the housing by means of apertures 10 in the PCB.
  • the cover 11 is square or rectangular in section.
  • This cover 11 includes porous material, for example a sinter, for the admittance of gas.
  • the cover 11 could comprise a solid shell of pressed metal, in which case the PCB of would incorporate apertures for the gas .
  • the cover 12 comprises a straight cylindrical wall 13 having a dome 14 as a lid.
  • the wall 13 and dome 14 may be of one-piece construction.
  • This sensor includes an apertured PCB for the admittance of gas .
  • the cover of the Figure 4 embodiment is less simple to manufacture than the basic cubic shape of the cover of the Figure 3 embodiment. However, the domed lid ensures that a greater proportion of light is directed onto the detector.
  • the cover 15 comprises a pipe 16, one end portion 17 of which is arranged to surround the source 2 of IR radiation.
  • the other end portion 18 of the pipe is arranged to surround the detector 4.
  • the pipe 16 forms an inverted "U" over the PCB.
  • the pipe 16 may comprise a sinter or else have a plurality of apertures (not shown) in its walls.
  • An advantage of this embodiment is that the pipe provides a predefined optical path for radiation traveling from the source to the detector. Thus, stray light is minimised.
  • the inverted "U" shape of the pipe provides a relatively long optical path as well as providing a large surface area for gas to diffuse into the cover.
  • the source 2 and detector 4 are spaced apart.
  • the cover 19 comprises a solid metallic shell arranged to provide an elongated channel between the source 2 and the detector4. In this embodiment, diffusion of gas into the housing is effected by means of apertures in the PCB .
  • the cover 19 of Figure 6 may be square or rectangular in cross section, as illustrated in Figure 7a. Alternatively, the cover may have a curved upper surface so that it is arch- shaped in cross section as shown in Figure 7b. Of course, the cover could take on any shape required, for example domed, pyramidal, etc, in order to enhance the proportion of radiation incident on the detector.
  • the gas admittance means could comprise apertures in the PCB, apertures in the cover, a sinter forming part of the cover or any combination of these.
  • a reflector may be located adjacent the source of IR radiation and arranged to reflect light in a desired direction or range of directions .
  • a replaceable particle filter for example a microporous membrane of Gore-Tex ® , may be provided over the gas sensor in order to prevent dirt particles, water droplets and other contaminants from entering the sensor.
  • a temperature sensor in the form of a thermistor, for example, may be incorporated in the sensor to provide a signal representing the temperature in the sensor to a control system, which employs suitable algorithms to provide temperature compensation of the output signal from the detector.
  • the invention is particularly suitable for detecting levels of carbon dioxide in an environment. Alternatively, an increase in concentration of carbon dioxide levels may be detected.
  • the gas sensor constructed according to the invention typically has an optical path length in the range of forty to sixty millimetres approximately. It has been found that this is suitable for detecting levels of carbon dioxide in the range of 500 ppm to 10,000 ppm.
  • the IR source and detector may be tuned to the absorption band of carbon dioxide at 4.2 microns.
  • a gas sensor configured to detect carbon dioxide is suitable for a wide range of applications as such a sensor can detect the presence of humans or animals in an environment .

Abstract

A gas sensor (1) comprises an optical source (2) and detector means (4) sensitive to light from the source. The source and detector are electrically and physically connected to a circuit board (PCB) (3) which, together with a cover (5), forms part of a housing (6) for the source and detector. The sensor further comprises means arranged, in use, to admit gas into the housing, such as a porous cover or apertures in the PCB. The mounting of the source and detector onto a circuit board greatly simplifies the manufacture of such gas sensors. Advantageously, the sensor further includes a temperature sensor arranged to detect temperature inside the housing. Signals from the temperature sensor can be used to compensate for changes in the gas sensor output with changes in ambient temperature.

Description

GAS SENSORS
FIELD OF THE INVENTION
This invention relates to apparatus for, and methods of, sensing gasses . The invention particularly relates to such methods and devices in which optical radiation is transmitted through a gas and subsequently detected to provide information concerning the gas .
BACKGROUND OF THE INVENTION
In a typical gas monitor, an infrared source is arranged to emit radiation, which passes through a gas to be monitored. Infrared radiation is absorbed by the gas and that remaining is subsequently detected by an infrared detector. A comparison is made between the source intensity and the intensity of radiation detected following passage through the gas to give the concentration of a target gas .
The present invention seeks to provide a gas sensing device, which although manufactured economically from a minimal number of inexpensive components, performs its function as well as more sophisticated sensors. SUMMARY OF THE INVENTION
The invention provides a gas sensor comprising an optical source and detector means sensitive to light from the source, the source and detector being electrically connected to a circuit board which forms part of a housing for the source and detector, and the sensor further comprising means arranged, in use, to admit gas into the housing.
The mounting of the source and detector onto a circuit board greatly simplifies the manufacture of such gas sensors. Previously, it has been thought desirable to mount the source and detector in special chambers, the inner contours of which are arranged to minimise stray ligh . Although such a gas sensor has good performance characteristics, the method of manufacturing the chamber and mounting the components therein is time-consuming and therefore more costly.
Preferably, the means for admitting gas into the housing comprises apertures in the housing, which apertures may be formed in the circuit board. Alternatively, or additionally, part of the housing may comprise sintered material to admit gas to the sensor.
Advantageously, the gas sensor further includes a temperature sensor arranged to detect temperature inside the housing. The output from the temperature sensor may be input to a control system arranged to provide a signal to compensate for changes in the sensor output with ambient temperature .
The invention lends itself to the monitoring of carbon dioxide levels at and above critical and is therefore suitable for the detection of the presence of humans or animals in an enclosed environment . Therefore, the invention may be employed in a variety of security and rescue applications .
BRIEF DESCRIPTION OF THE FIGURES
The invention will now be described, by way of example, with reference to the accompanying drawings, in which: -
Figure 1 is a sectional view of a gas sensor constructed according to
the invention;
Figure 2 is a sectional view of an alternative gas sensor constructed
according to the invention;
Figure 3 is a sectional view of another alternative gas sensor constructed according to the invention;
Figure 4 is a sectional view of a further alternative gas sensor constructed according to the invention; Figure 5 is a sectional view of a further alternative gas sensor constructed according to the invention;
Figure 6 is a sectional view of a further alternative gas sensor constructed according to the invention; and
Figures 7a and 7b are cross sectional views of channels suitable for inclusion in the sensor of Figure 6.
DESCRIPTION OF A PREFERRED EMBODIMENT
Like reference numerals relate to like parts throughout the specification.
With reference to Figure 1, a gas sensor constructed according to the invention is illustrated and indicated generally by the reference numeral 1. The gas sensor 1 comprises a source 2 of infrared (IR) radiation, electrically connected to, and physically mounted on, a printed circuit board (PCB) 3. The sensor 1 further comprises an infrared detector 4, which includes a bandpass filter. The detector 4 is also electrically connected to, and physically mounted on, the PCB 3. Suitable detectors include photodiodes, thermopiles and pyroelectric devices .
A cover 5 is provided for the source 2 and detector 4. The cover 5, together with the PCB 3 forms a housing 6 for the components of the sensor 1. The interior surfaces of the housing 6 form an optical cavity. In order to obtain good reflectance of IR radiation in the optical cavity, the interior surfaces of the cover are coated with a metallic layer, for example gold. Any material that is highly reflective to IR radiation may be employed. The surface of the PCB onto which the components are mounted may also be coated with IR reflective material .
The cover 5 has a tapered wall 7 with a curved end portion 8 arranged so that, in the sectional view of Figure 1, the cover 5 resembles the shape of a thimble. In this embodiment, at least a portion of the cover 5 comprises a sinter, to allow gas to be admitted into the housing 6 by diffusion.
In use, the source 2 produces broadband IR radiation, which is reflected by the surfaces of the cavity and absorbed by the gas in the housing to a degree proportional to the amount of gas present. A range of wavelengths of the broadband IR radiation not absorbed by the gas is detected at the detector 4. The detector 4 generates an electrical signal corresponding to the strength of the detected IR radiation. This signal is input to processing electronics (not shown) arranged to ) determine the concentration of gas present in the housing. The concentration is related to the intensity by the following equation:
/ = A where I is the intensity of radiation detected by the detector, 10 is the intensity of radiation emitted at the source, e is effectively a constant which is dependent on the particular gas being monitored, c is the gas concentration and I is the distance travelled by the radiation through the gas.
The sensor and processing electronics may be configured to detect an increase or decrease (Δc) in concentration of the gas being sensed. Alternatively, absolute measurements of the concentration of a particular gas may be determined.
An alternative arrangement of the sensor of Figure 1 is shown in Figure 2. In this embodiment, the cover 9 comprises a solid shell of pressed metal . Gas is able to diffuse into the housing by means of apertures 10 in the PCB.
Another alternative sensor constructed according to the invention is shown in Figure 3. In this embodiment, the cover 11 is square or rectangular in section. This cover 11 includes porous material, for example a sinter, for the admittance of gas. Alternatively, the cover 11 could comprise a solid shell of pressed metal, in which case the PCB of would incorporate apertures for the gas . The advantage of this embodiment is that the cover is straightforward to manufacture. In the sensor of Figure 4, the cover 12 comprises a straight cylindrical wall 13 having a dome 14 as a lid. The wall 13 and dome 14 may be of one-piece construction. This sensor includes an apertured PCB for the admittance of gas . The cover of the Figure 4 embodiment is less simple to manufacture than the basic cubic shape of the cover of the Figure 3 embodiment. However, the domed lid ensures that a greater proportion of light is directed onto the detector.
A further alternative gas sensor is illustrated in Figure 5. In this embodiment, the cover 15 comprises a pipe 16, one end portion 17 of which is arranged to surround the source 2 of IR radiation. The other end portion 18 of the pipe is arranged to surround the detector 4. The pipe 16 forms an inverted "U" over the PCB. The pipe 16 may comprise a sinter or else have a plurality of apertures (not shown) in its walls. An advantage of this embodiment is that the pipe provides a predefined optical path for radiation traveling from the source to the detector. Thus, stray light is minimised. The inverted "U" shape of the pipe provides a relatively long optical path as well as providing a large surface area for gas to diffuse into the cover.
In the alternative sensor of Figure 6, the source 2 and detector 4 are spaced apart. The cover 19 comprises a solid metallic shell arranged to provide an elongated channel between the source 2 and the detector4. In this embodiment, diffusion of gas into the housing is effected by means of apertures in the PCB . The cover 19 of Figure 6 may be square or rectangular in cross section, as illustrated in Figure 7a. Alternatively, the cover may have a curved upper surface so that it is arch- shaped in cross section as shown in Figure 7b. Of course, the cover could take on any shape required, for example domed, pyramidal, etc, in order to enhance the proportion of radiation incident on the detector.
The gas admittance means could comprise apertures in the PCB, apertures in the cover, a sinter forming part of the cover or any combination of these.
Further variations may be made without departing from the scope of the invention. For example, a reflector may be located adjacent the source of IR radiation and arranged to reflect light in a desired direction or range of directions .
A replaceable particle filter, for example a microporous membrane of Gore-Tex ®, may be provided over the gas sensor in order to prevent dirt particles, water droplets and other contaminants from entering the sensor.
A temperature sensor (not shown) in the form of a thermistor, for example, may be incorporated in the sensor to provide a signal representing the temperature in the sensor to a control system, which employs suitable algorithms to provide temperature compensation of the output signal from the detector. The invention is particularly suitable for detecting levels of carbon dioxide in an environment. Alternatively, an increase in concentration of carbon dioxide levels may be detected. The gas sensor constructed according to the invention typically has an optical path length in the range of forty to sixty millimetres approximately. It has been found that this is suitable for detecting levels of carbon dioxide in the range of 500 ppm to 10,000 ppm. The IR source and detector may be tuned to the absorption band of carbon dioxide at 4.2 microns. A gas sensor configured to detect carbon dioxide is suitable for a wide range of applications as such a sensor can detect the presence of humans or animals in an environment .

Claims

1. A gas sensor comprising an optical source and detector means sensitive to light from the source, the source and detector being electrically connected to a circuit board which forms part of a housing for the source and detector, and the sensor further comprising means arranged, in use, to admit gas into the housing.
2. A gas sensor as claimed in claim 1, wherein the means for admitting gas into the housing comprises at least one aperture in the circuit board.
3. A gas sensor as claimed in claim I or 2, in which the means for admitting gas into the housing comprises at least one aperture in the housing.
4. A gas sensor as claimed in anyone of claims I to 3 , in which the means for admitting gas into the housing comprises sintered filter material which forms at least part of the housing.
5. A gas sensor as claimed in any previous claim, in which at least part of the interior of the housing is coated with IR reflective material .
6. A gas sensor as claimed in any previous claim, further comprising a reflector associated with the source.
7. A gas sensor as claimed in any preceding claim, further comprising processing electronics arranged, in use, to determine the presence of a predetermined gas in dependence on signals from the detector.
8. A gas sensor as claimed in claim 7, in which the processing electronics is arranged to detect a change in concentration of the predetermined gas .
9. A gas sensor as claimed in claim 7, in which the processing electronics is arranged to determine absolute concentration of the predetermined gas
10. A gas sensor as claimed in any previous claim, further comprising a temperature sensor.
11. A gas sensor as claimed in claim 10, further comprising compensating electronics arranged to compensate for changes in temperature detected by the temperature sensor.
12. A gas sensor as claimed in any previous claim, further comprising a particle filter.
13. A carbon dioxide detector including a gas sensor as claimed in anyone of claims 1 to 9.
14. A gas detection system including a gas sensor as claimed in anyone of claims 1 to 9.
PCT/GB2003/003782 2002-09-03 2003-09-02 Gas sensors WO2004023113A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2003260767A AU2003260767A1 (en) 2002-09-03 2003-09-02 Gas sensors

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0220351.1 2002-09-03
GB0220351A GB2392721A (en) 2002-09-03 2002-09-03 Gas sensors

Publications (1)

Publication Number Publication Date
WO2004023113A1 true WO2004023113A1 (en) 2004-03-18

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2003/003782 WO2004023113A1 (en) 2002-09-03 2003-09-02 Gas sensors

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AU (1) AU2003260767A1 (en)
GB (1) GB2392721A (en)
WO (1) WO2004023113A1 (en)

Cited By (5)

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WO2005054827A1 (en) * 2003-12-02 2005-06-16 City Technology Limited Gas sensor
WO2005062024A1 (en) * 2003-12-20 2005-07-07 Robert Bosch Gmbh Gas sensor
EP2163208A2 (en) 2008-07-11 2010-03-17 Olympus Medical Systems Corp. Tissue fastener
DE102009036114B3 (en) * 2009-08-05 2010-09-02 Dräger Safety AG & Co. KGaA Infrared-optical gas measurement device for use in warning- and alarm system for monitoring concentration of e.g. explosive gas in industry, has split washers or perforated disks arranged in region of gas inlet opening
JP2014016268A (en) * 2012-07-10 2014-01-30 Asahi Kasei Electronics Co Ltd Gas sensor

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DE10144873A1 (en) * 2001-09-12 2003-03-27 Bosch Gmbh Robert Micromechanical heat conductivity sensor used for analyzing gas mixtures containing hydrogen and/or helium has a thermally insulating membrane covered on one or both of its sides by a porous covering plate which permits gas diffusion
US7244939B2 (en) 2003-12-09 2007-07-17 Dynament Limited Gas sensor
GB2401432B (en) * 2003-12-09 2005-05-04 Dynament Ltd Gas sensor
SE534082C2 (en) 2004-12-29 2011-04-26 Senseair Ab A gas detecting arrangement
DE102005018470A1 (en) * 2005-04-21 2006-10-26 Robert Bosch Gmbh Optical gas sensor
US7214939B1 (en) * 2005-11-21 2007-05-08 Airware, Inc. Ultra low power NDIR carbon dioxide sensor fire detector
DE102007006155A1 (en) * 2007-02-07 2008-08-14 Tyco Electronics Raychem Gmbh Substrate with integrated filter for gas sensor arrangements
GB0705356D0 (en) 2007-03-21 2007-04-25 Alphasense Ltd Optical absorption gas sensor
JP2009092545A (en) 2007-10-10 2009-04-30 Panasonic Corp Composite sensor for detecting angular velocity and acceleration
SE534685C2 (en) * 2008-12-12 2011-11-15 Senseair Ab Gas sensor arrangement for circuit boards
SE535267C2 (en) * 2009-10-26 2012-06-12 Senseair Ab A measurement cell adapted to a spectral analysis
US8922381B2 (en) 2011-07-20 2014-12-30 Logico2 Online Sarl Device and system for gas leakage detection and alarm

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Publication number Priority date Publication date Assignee Title
WO2005054827A1 (en) * 2003-12-02 2005-06-16 City Technology Limited Gas sensor
US7541587B2 (en) 2003-12-02 2009-06-02 City Technology Limited Gas sensor
WO2005062024A1 (en) * 2003-12-20 2005-07-07 Robert Bosch Gmbh Gas sensor
US7880886B2 (en) 2003-12-20 2011-02-01 Robert Bosch Gmbh Gas sensor
EP2163208A2 (en) 2008-07-11 2010-03-17 Olympus Medical Systems Corp. Tissue fastener
DE102009036114B3 (en) * 2009-08-05 2010-09-02 Dräger Safety AG & Co. KGaA Infrared-optical gas measurement device for use in warning- and alarm system for monitoring concentration of e.g. explosive gas in industry, has split washers or perforated disks arranged in region of gas inlet opening
JP2014016268A (en) * 2012-07-10 2014-01-30 Asahi Kasei Electronics Co Ltd Gas sensor

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Publication number Publication date
GB2392721A (en) 2004-03-10
GB0220351D0 (en) 2002-10-09
AU2003260767A1 (en) 2004-03-29

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