EP2018535A2 - Gas detector having an acoustic measuring cell and selectively adsorbing surface - Google Patents
Gas detector having an acoustic measuring cell and selectively adsorbing surfaceInfo
- Publication number
- EP2018535A2 EP2018535A2 EP07725143A EP07725143A EP2018535A2 EP 2018535 A2 EP2018535 A2 EP 2018535A2 EP 07725143 A EP07725143 A EP 07725143A EP 07725143 A EP07725143 A EP 07725143A EP 2018535 A2 EP2018535 A2 EP 2018535A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- measuring cell
- acoustic measuring
- adsorbing surface
- gas detector
- selectively adsorbing
- 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.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/34—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor
- G01N29/348—Generating the ultrasonic, sonic or infrasonic waves, e.g. electronic circuits specially adapted therefor with frequency characteristics, e.g. single frequency signals, chirp signals
-
- 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
- G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/24—Probes
- G01N29/2418—Probes using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics
- G01N29/2425—Probes using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics optoacoustic fluid cells therefor
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/44—Processing the detected response signal, e.g. electronic circuits specially adapted therefor
- G01N29/4481—Neural networks
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/40—Concentrating samples
- G01N1/405—Concentrating samples by adsorption or absorption
-
- 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
- G01N21/1702—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids
- G01N2021/1704—Systems in which incident light is modified in accordance with the properties of the material investigated with opto-acoustic detection, e.g. for gases or analysing solids in gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/021—Gases
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/042—Wave modes
- G01N2291/0423—Surface waves, e.g. Rayleigh waves, Love waves
Definitions
- Patent application Gas detector with acoustic measuring cell and selectively adsorbing surface
- the invention relates to a gas detector with acoustic measuring cell and selectively adsorbing surface.
- TD Desorption
- GC gas chromatography
- MSD mass selective detector
- FID flame ionization detector
- Transformation can be done on a surface or in solution. There are two ways to differentiate:
- DE 199 13 220 C2 describes a collection medium which has a selectively adsorbing surface. On this can be adsorbed substances to be examined, which can then be desorbed again to a subsequent measurement. This desorption can also take place thermally.
- DE 199 13 220 C2 is mentioned as a possible measurement method for determining which substance has been desorbed, including photoacoustics. From DE 199 13 220 C2, therefore, a measuring device is known in which desorbed by an adsorbing surface Gases can be examined photoacoustically. Thus, the desorbed gases are to be excited by a light source, usually a laser, to produce a photoacoustic signal by absorption. Also known from WO 03/026774 A1 is a device in which gases desorbed from a surface can be examined photoacoustically.
- Object of the present invention is to provide a gas detector and a method for the analysis of gas components, which allows high selectivity and rapid measurements at low equipment cost
- the gas detector according to the invention has a selectively adsorbing surface and an acoustic measuring cell.
- the selectively adsorbing surface and the acoustic measuring cell can be arranged relative to one another in such a way that gases desorbed from the adsorbing surface by means of thermal desorption are converted into the acoustic
- the gases When the gases enter the acoustic measuring cell, they trigger a pressure wave there, which can be measured by one or more acoustic sensors, as a rule microphones, which are arranged in the acoustic measuring cell.
- a surface on which the gases to be investigated are selectively adsorbed is selected as the selectively adsorbing surface. This surface must be exposed to the gas mixture, normally air, which must be checked for the presence of the gases to be tested.
- a radiation source is present whose radiation can be absorbed by gases in the acoustic measuring cell, whereby the radiation source can emit radiation in a given wavelength range, preferably in a wavelength range lying in the infrared range Radiation takes place heating of the gas, which leads to an expansion and thus to a pressure wave
- This pressure wave can be measured in the acoustic measuring cell by Schallbuchaufsacrificing, usually microphones, by this measure, the selectivity of the measurement is increased
- the signal obtained depends on the absorption
- the radiation through the gas from Since the radiation source can emit radiation in a given wavelength range and different gases in different Wavelength ranges emit, can from the received sound pressure signal on the
- the radiation source is a tunable monochromatic light source, such as a diode laser, Quantum Cascade laser, or an optical parametric oscillator (OPO).
- a superluminescent LED can be used.
- a thermal infrared radiator with tunable bandpass filter characterized by a continuously adjustable transmission can be used.
- a window is present in the acoustic measuring cell through which radiation can enter and / or a window exists, through which radiation can escape.
- windows are to be selected which are as transparent as possible to the radiation which is to pass through.
- the photoacoustic signal could also be attenuated since only a weaker pressure wave could form if the acoustic measuring cell had more openings.
- the acoustic measuring cell is partially open so that the gas can pass from the selectively adsorbing surface into the measuring cell. There, however, only a small opening is effective because the selectively adsorbing surface acts partially as a closure.
- a particularly suitable gas detector is achieved if the selectively adsorbing surface is arranged on a movable, in particular a rotatable, element. This makes it possible to transport the selectively adsorbing surface into the region in which the adsorption of the gases is to take place without any particular effort. Subsequently, the selectively adsorbing surface on which the to are adsorbed to the acoustic measuring cell. There, the selective adsorbing surface can be desorbed by thermal desorption as described and then reused for a measurement by being transported back into the region of the gases to be investigated.
- a suitable structure of the gas detector is obtained when the movable element is constructed of a transparent material which is covered with a radiation-absorbing layer on which the selectively adsorbing surface is applied.
- the thermal desorption may be by radiation from which penetrates through the transparent material without significant absorption and is then absorbed in the radiation-absorbing layer.
- the radiation-absorbing layer is heated and thus the absorbent layer is heated, which is thermally desorbed as a result of the heating.
- a radiation source may optionally be arranged on the side of the movable element facing away from the acoustic measuring cell. There is more space.
- a particularly suitable form for the movable element is a disc.
- the selectively adsorbing surface can be easily moved by rotation of the disc in the region of the gas to be examined and back to the measuring cell. It is understood that a plurality of selectively adsorbing surfaces can be applied to the movable element. Thus, the adsorption can be done on one surface while another surface is desorbed. This allows more measurements to be taken at the same time. If differently adsorbing surfaces are provided, a plurality of different gases can be detected with a measuring arrangement without costly modification.
- heating energy is, as mentioned above, to provide a radiation source, in particular a laser.
- a radiation source in particular a laser.
- the selectively adsorbing surface with comparatively high power density heat can be supplied.
- the heat released from the selectively adsorbing surface to the environment is obviously lower than when heating at low power.
- the heating would take longer, so that due to the longer time a higher amount of heat would be released to the environment.
- the thermal desorption can be carried out at different temperatures, which depend on the material to be desorbed.
- a statement about the desorbed gas that is to say the previously adsorbed gas, can already be made by selecting the desorption temperature.
- the signal obtained in the thermal desorption with low desorption temperature can be attributed only to gases that can be desorbed even at the lower temperature.
- the amount of energy supplied and thus the resulting heating can be dosed usually without much effort.
- a gap is formed between the selectively adsorbing surface and the acoustic measuring cell, which, of course, must not be too large, it is possible to carry out a measurement.
- Such a gap makes it possible to move the adsorbing surface back and forth again to the acoustic measuring cell without any disturbing contact with the housing of the acoustic measuring cell. Such a touch could otherwise be avoided only by a complex motion control.
- the acoustic measuring cell should have an opening at least on the side facing the selectively adsorbing surface. In this way, the desorbed gases can easily get into the acoustic measuring cell and form a pressure wave there.
- the measuring cell acoustically forms a Helmholtz resonator with a resonance frequency in the kHz range. This boosts the pressure signal.
- the gas detector is particularly suitable for the detection of indoor pollutants and / or control of ventilation systems. Especially in ventilation systems, but also in pollutants indoors, a quick measurement is required, which is possible with the described gas detector. This allows a needs-based control of ventilation systems. A needs-based control of ventilation systems allows a high air quality with low energy consumption. Other conceivable
- gas detector Applications of the gas detector are the detection of explosives and explosives as well as toxic gases in public accessible buildings. Also, unpleasant odors in the indoor air or in the supply air of ventilation systems can be detected. Of the Detector is also suitable for checking compliance with limit values, such as
- the gas detector is particularly suitable for the detection of molecules with low vapor pressure.
- a selectively adsorbing surface is provided. This is then moved to the area in which the gas components are to be determined. In the above use, this would be the air in the interior. There the adsorption takes place with the gases to be examined. Subsequently, the selectively adsorbing surface is moved to an acoustic measuring cell.
- the desorbed gases reach the acoustic measuring cell. There, the pressure wave generated by the desorbed gases with one or more acoustic sensors, in particular microphones, which are arranged in the acoustic measuring cell, detected.
- Figure 1 shows an entire structure of the measuring arrangement
- FIG. 2 shows a disk with several selectively adsorbing areas
- the gas detector is divided into 3 units.
- the unit I comprises a substrate on which selectively adsorbing regions are arranged;
- Unit II essentially the acoustic measuring cell and the associated internals;
- Unit III is the control and power supply of the detector
- a transparent substrate 1 in the middle infrared Shown is a transparent substrate 1 in the middle infrared.
- the substrate must have a low thermal conductivity and a low temperature expansion coefficient. Therefore, glass, quartz glass and synthetic quartz are suitable.
- a thin metal film 2 is applied, which is absorbing in the near infrared.
- a surface coated with silver (I) sulfide is suitable.
- An electric motor 4 rotates the transparent substrate 1 formed as a disk.
- an acoustic measuring cell 5 whose interior volume is 1 to 2 cm 2 .
- the infrared radiation of the laser 6 is concentrated in optical components, preferably a lens 7, and passes through the transparent substrate 1 for the infrared radiation on the metal film 2, which absorbs the infrared radiation. Thereby, the metal film is heated and releases the heat to the applied selectively adsorptive layer 3. This leads to a thermal desorption of adsorbed gases which reach the acoustic measuring cell 5.
- the switching system 8 ensures that the electric motor 4 rotates the disc at the correct speed and stops at the appropriate time for desorption.
- the switching system 8 also ensures that the desorption laser 6 is desorbed when the layer to be desorbed is located in front of the acoustic measuring cell 5.
- the Switching system 8 provides for different laser current and different if necessary
- the acoustic measuring cell 5 has two windows 10. These windows allow the passage of radiation from a radiation source 17 described in more detail below and must be transparent to their radiation.
- the acoustic measuring cell 5 also has openings 1 1 to the gas outlet. The openings 1 1 can be closed and opened by a closing mechanism 12. Opposite the permanently opened opening, which is the selectively adsorbing
- connection between the selectively adsorbing surface and the acoustic measuring cell forms a first axis
- the radiation 16 emitted from the radiation source 17 propagates along a second axis and the gas flows along a third axis, wherein the three axes are perpendicular to each other and form a Cartesian coordinate system.
- the light of the near infrared diode laser 6 is to be guided by means of an optical fiber 15 through the acoustic measuring cell.
- the radiation source 17 is preferably a very small heat radiation source.
- the desired infrared wavelength range is filtered out.
- the desired wavelength range is the wavelength range in which the gases to be detected absorb radiation particularly well. It is usually a wavelength interval of 2 microns to 10 microns
- the electronic system 20 the average voltage, the frequency and amplitude of the modulation voltage. Usual is one
- Modulation frequency of 20-80 Hz The generated photoacoustic signal thus has the same modulation frequency.
- preamplifiers and filters 21 are provided for the microphones 13, 14. These amplify the very small microphone signals to a level suitable for converting the analog signals into digital signals.
- a circuit 22 is present. This collects and stores the measured data, evaluates them to determine the concentration of the measured components. The evaluation takes into account the type of selective adsorber, the wavelength of the radiation 16 used, the desorption temperature achieved, the intensity of the acoustic signal triggered by the pressure wave produced during the desorption and the intensity of the photoacoustic signal caused by the radiation 16. With known concentrations of gases to be examined, a calibration of the gas detector can be achieved. For further improvement, a neural network can be used. With the aid of a display circuit 23, the parameter values, the structure and the
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- Physics & Mathematics (AREA)
- Immunology (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Pathology (AREA)
- General Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Engineering & Computer Science (AREA)
- Optics & Photonics (AREA)
- Artificial Intelligence (AREA)
- Evolutionary Computation (AREA)
- Signal Processing (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102006023061A DE102006023061B4 (en) | 2006-05-17 | 2006-05-17 | Gas detector with acoustic measuring cell and selective adsorbing surface |
PCT/EP2007/004223 WO2007131739A2 (en) | 2006-05-17 | 2007-05-12 | Gas detector having an acoustic measuring cell and selectively adsorbing surface |
Publications (1)
Publication Number | Publication Date |
---|---|
EP2018535A2 true EP2018535A2 (en) | 2009-01-28 |
Family
ID=38585856
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP07725143A Withdrawn EP2018535A2 (en) | 2006-05-17 | 2007-05-12 | Gas detector having an acoustic measuring cell and selectively adsorbing surface |
Country Status (4)
Country | Link |
---|---|
US (1) | US8302461B2 (en) |
EP (1) | EP2018535A2 (en) |
DE (1) | DE102006023061B4 (en) |
WO (1) | WO2007131739A2 (en) |
Families Citing this family (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2098851A1 (en) * | 2008-03-07 | 2009-09-09 | Nederlandse Organisatie voor toegepast- natuurwetenschappelijk onderzoek TNO | A thermal desorption gas analyzer and a method for analyzing a gaseous environment |
FR2974413B1 (en) * | 2011-04-21 | 2014-06-13 | Commissariat Energie Atomique | PHOTOACOUSTIC GAS DETECTOR WITH HELMHOLTZ CELL |
DE102011102055B8 (en) | 2011-05-19 | 2013-04-25 | Eads Deutschland Gmbh | Device for testing a fiber composite component for contamination |
US8594507B2 (en) * | 2011-06-16 | 2013-11-26 | Honeywell International Inc. | Method and apparatus for measuring gas concentrations |
US10488292B1 (en) | 2014-10-16 | 2019-11-26 | Leak Detection Technologies, Inc. | Leak detection system |
US9841344B2 (en) * | 2016-03-29 | 2017-12-12 | Leak Detection Technologies, Inc. | System and methods for monitoring leaks in underground storage tanks |
FR3084746B1 (en) * | 2018-08-03 | 2020-10-16 | Mirsense | PHOTOACOUSTIC GAS SENSOR USING AN ILLUMINATION WAVELENGTH MODULATION METHOD |
EP3715842B1 (en) * | 2019-03-26 | 2021-05-19 | Infineon Technologies AG | Mems gas sensor |
IT201900008442A1 (en) * | 2019-06-10 | 2020-12-10 | Consiglio Nazionale Ricerche | Chemical analysis system using gas chromatography separation and spectrometry of sample mixtures |
EP4241065A1 (en) * | 2020-11-03 | 2023-09-13 | Gasera Ltd | Device and method for detecting benzene |
Family Cites Families (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4067653A (en) * | 1976-08-27 | 1978-01-10 | Nasa | Differential optoacoustic absorption detector |
JPH06165933A (en) | 1992-09-29 | 1994-06-14 | Mitsubishi Electric Corp | Nitrogen oxide selectively adsorbing material reaction control method therefor and device for detecting, adsorption-removing and decomposing gas using them |
US5777324A (en) * | 1996-09-19 | 1998-07-07 | Sequenom, Inc. | Method and apparatus for maldi analysis |
US5933245A (en) * | 1996-12-31 | 1999-08-03 | Honeywell Inc. | Photoacoustic device and process for multi-gas sensing |
US7578973B2 (en) * | 1998-11-13 | 2009-08-25 | Mesosystems Technology, Inc. | Devices for continuous sampling of airborne particles using a regenerative surface |
DE19913220C2 (en) | 1999-03-24 | 2001-07-05 | Gsf Forschungszentrum Umwelt | Process for the detection of trace substances and / or environmental properties |
US7034943B1 (en) | 2000-03-03 | 2006-04-25 | Aritron Intrumente AG | Gas sensors |
FR2815122B1 (en) * | 2000-10-06 | 2003-02-07 | Univ Reims Champagne Ardenne | GAS DETECTION DEVICE |
US6683300B2 (en) * | 2001-09-17 | 2004-01-27 | Science & Engineering Services, Inc. | Method and apparatus for mass spectrometry analysis of common analyte solutions |
US6620630B2 (en) * | 2001-09-24 | 2003-09-16 | Extraction Systems, Inc. | System and method for determining and controlling contamination |
US6707039B1 (en) * | 2002-09-19 | 2004-03-16 | Agilent Technologies, Inc. | AP-MALDI target illumination device and method for using an AP-MALDI target illumination device |
EP2722869A1 (en) * | 2002-10-29 | 2014-04-23 | Target Discovery, Inc. | Method for increasing ionization efficiency in mass spectroscopy |
US6639217B1 (en) * | 2002-12-20 | 2003-10-28 | Agilent Technologies, Inc. | In-line matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) systems and methods of use |
US20040183009A1 (en) * | 2003-03-17 | 2004-09-23 | Reilly James P. | MALDI mass spectrometer having a laser steering assembly and method of operating the same |
US7138625B2 (en) * | 2003-05-02 | 2006-11-21 | Agilent Technologies, Inc. | User customizable plate handling for MALDI mass spectrometry |
US6953928B2 (en) * | 2003-10-31 | 2005-10-11 | Applera Corporation | Ion source and methods for MALDI mass spectrometry |
US7405396B2 (en) * | 2005-05-13 | 2008-07-29 | Applera Corporation | Sample handling mechanisms and methods for mass spectrometry |
US7645987B2 (en) * | 2005-09-22 | 2010-01-12 | Academia Sinica | Acoustic desorption mass spectrometry |
US7619217B2 (en) * | 2006-05-26 | 2009-11-17 | Purdue Research Foundation | High power laser induced acoustic desorption probe |
US7398672B2 (en) * | 2006-07-12 | 2008-07-15 | Finesse Solutions, Llc. | System and method for gas analysis using photoacoustic spectroscopy |
TW200842359A (en) * | 2007-04-30 | 2008-11-01 | Univ Nat Sun Yat Sen | A method of mass spectrometry to combine electrospray ionization with laser-induced acoustic desorption |
US7808640B2 (en) * | 2008-07-30 | 2010-10-05 | Honeywell International Inc. | Photoacoustic spectroscopy system |
-
2006
- 2006-05-17 DE DE102006023061A patent/DE102006023061B4/en not_active Expired - Fee Related
-
2007
- 2007-05-12 WO PCT/EP2007/004223 patent/WO2007131739A2/en active Application Filing
- 2007-05-12 US US12/300,952 patent/US8302461B2/en not_active Expired - Fee Related
- 2007-05-12 EP EP07725143A patent/EP2018535A2/en not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO2007131739A2 * |
Also Published As
Publication number | Publication date |
---|---|
DE102006023061A1 (en) | 2007-11-22 |
US20090183552A1 (en) | 2009-07-23 |
DE102006023061B4 (en) | 2008-08-14 |
WO2007131739A2 (en) | 2007-11-22 |
WO2007131739A3 (en) | 2008-01-03 |
US8302461B2 (en) | 2012-11-06 |
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