EP1776579A2 - Systeme de capteur a micro-decharge - Google Patents

Systeme de capteur a micro-decharge

Info

Publication number
EP1776579A2
EP1776579A2 EP05784981A EP05784981A EP1776579A2 EP 1776579 A2 EP1776579 A2 EP 1776579A2 EP 05784981 A EP05784981 A EP 05784981A EP 05784981 A EP05784981 A EP 05784981A EP 1776579 A2 EP1776579 A2 EP 1776579A2
Authority
EP
European Patent Office
Prior art keywords
electrodes
electrode
waveguide
discharge
gap
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Withdrawn
Application number
EP05784981A
Other languages
German (de)
English (en)
Inventor
Ulrich Bonne
Brian C. Krafthefer
Stephen R. Shiffer
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.)
Honeywell International Inc
Original Assignee
Honeywell International Inc
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 US10/915,577 external-priority patent/US20050142035A1/en
Application filed by Honeywell International Inc filed Critical Honeywell International Inc
Publication of EP1776579A2 publication Critical patent/EP1776579A2/fr
Withdrawn legal-status Critical Current

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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
    • G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
    • G01N21/66—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence
    • G01N21/67—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light electrically excited, e.g. electroluminescence using electric arcs or discharges
    • 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—General constructional details of gas analysers, e.g. portable test equipment concerning the detector specially adapted to detect a particular component
    • G01N33/0037—NOx
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

  • the present invention pertains to detection of fluids.
  • the invention pertains to plasma structures, and more particularly to the application of the structures as sensors for the identification and quantification of fluid components.
  • the term "fluid” may be used as a generic term that includes gases and liquids
  • GC-GC and GC-MS gas chromatograph - mass spectrometer
  • GC- AED gas chromatograph - atomic emission detector
  • thermal conductivity sensors > 10 to 100 ppm of analyte
  • too selective to specific compounds such as fluorescence and electron-capture detectors
  • relatively high-cost such as the typical price tags in year 2003 of about $600, $3000 and upwards for many GC detectors
  • relatively high-power such as the AEDs (atomic emission detectors) which consume over 100 W.
  • the invention may be a sensor system having a discharge gap formed by electrodes.
  • a fluid to be sensed may enter the vicinity of a discharge at the gap.
  • An optical coupling may include a waveguide proximate to the discharge gap. Cleanliness of the optical coupling and one or more electrodes may be maintained by the discharge.
  • a processor may be coupled to the waveguide.
  • the electrodes and waveguide may have various configurations and arrangements.
  • Figure 1 shows a micro discharge device optically coupled to an optical multi-channel analyzer based on light inputs through interference filters
  • Figure 2 is a close view of a discharge gap to optical fiber interface
  • FIG. 3 shows a discharge gap housing attached to
  • Figure 4 shows a micro discharge device optically
  • Figure 5 is a close view of the Fabry-Perot type analyzer
  • Figure 6 shows a micro discharge device optically coupled to a spectrometer
  • Figure 7 is a graph of the relative intensity versus wavelength for a spectral emission of a glow discharge with a mixture of NO in N 2 ; '
  • Figure 8 is a table of angular sensitivity data for materials of various refractive indexes
  • Figure 9 is a table of Fabry-Perot filter design parameters for wavelength modulation in gas sensing
  • Figure 10 is a graph of a wavelength scan of a Fabry-Perot filter
  • Figure 11 is a sensor system having a silica chip to support the micro discharge electrodes
  • Figure 12 is a sensor system having no silica chip to support the micro discharge electrodes
  • Figure 13 shows a sensor situated in a spark-plug- like package
  • Figures 14 and 14a are cross-section diagrams of sensors revealing electrode enclosures
  • Figure 15 is a cutaway of the a sensor showing overlapping edges of the electrodes
  • Figure 16 shows a sensor having a concentric electrode relative to a light waveguide
  • Figure 17 is a cross-section view of concentric electrodes forming an annular discharge gap
  • Figures 18a and 18b are top views of an optical fiber and a pair of electrodes separated by a number of optical fibers
  • Figure 19a is a side cross-section and top view of two electrodes separated by an optical fiber.
  • Figure 19b is a side cross-section and top view of two concentric electrodes separated by a light waveguide.
  • the present .optical spectral / molecular emission- based NO (and other chemicals) sensor system may be a low power, low-mass and compact (the emissive glow discharge plasma of each element may be 10 to 100 microns in diameter) .
  • the system may have its plasma operate at about 1100 degrees C.
  • the system may be low-cost, rugged (no precision optical alignments needed) and maintain operational stability various kinds of environments. With adequate air filtering, sensor system operation may occur without noble gas purging, such as for exhaust gas composition measurements, along with high temperature plasma self-cleaning, signal processing and advantageous low-cost, compact and rugged packaging.
  • MDD may be used for optical transmission surface cleaning and for maintaining electrode isolation in an MDD detector application; that is, the same plasma discharge may be used to keep the observation window clean, by plasma-etching away any combustion-product deposits such as condensable tars and carbon-soot.
  • the same or a similar glow discharge may maintain cleanliness and (more importantly) the required electrical isolation of the soot-sensor electrodes of soot sensors.
  • One may co-locate a spectral-emissive and a soot sensor in one package. In other words, it is compatible and easy to integrate with soot sensor systems.
  • the silica chip may be eliminated and the discharge may be operated between two free-standing electrodes.
  • the same plasma discharge may maintain the required electrical insulation of the non-grounded micro-discharge electrode (magnified view of one example electrode tip in Figure 2) , or achieve such insulation by periodic power- cleaning cycles, which may or may not cause a pause in the measurement and the self-check cycle.
  • cyclone and impactor plate may occur with low ⁇ p to
  • sample gas flow ( Figure 14) .
  • Smart positioning between the end of the optical fiber and the photodiode may be used to detect optical fiber light components of small angles, as required by the chosen bandpass filter width.
  • the present system may be more compact, rugged and lower cost than chemiluminescence-based sensor systems. It may be more stable than metal-oxide or catalyst-based and conventional optical sensor systems and less energy consuming than ZrO2-based sensor systems.
  • the present system may be more tolerant to temperature change than other sensor systems, and more manufacturable than multi ⁇ layer ZrO2, metal oxide• or catalyst based sensor systems.
  • the present system may be lower cost than previous MDD-based NO x sensor systems. It may permit observation of NO spectral emissions in the IR. Also, it may allow co-planar design with one MDD as source and another as detector.
  • Spectral analysis of the MDD emission may rely on a scanning, narrow band-pass, MEMS Fabry-Perot (FP) filter, i.e., it is compact, versatile (having many channels), highly effective light intensity (despite the high mirror-etalon reflectivity if many (100 to 1000) MDDs are operated in parallel) and low-maintenance because the FP- filter operates in a sealed environment, and the only other optical surface exposed to sample gas is self- cleaned by the MDD.
  • FP Fabry-Perot
  • a micro discharge device (MDD) 11 is shown in systems 10, 20 and 30 of Figures 1, 4 and 6, respectively.
  • Device 11 may have one electrode 31 and another electrode 32 with ends facing each other to form a gap for providing a micro glow discharge 18.
  • the gap may be enclosed in a glass tube or hollow pipe 33.
  • Device 11 may have a soot electrode that may be kept clean of soot build-up.
  • the glow of device 11 may have a UV/visible spectrum as shown in a graph of Figure 7. That graph shows relative intensity versus wavelength in nm for a spectral emission of a glow discharge using 22.9 ppm of NO in N 2 in an environment of 700 Torr.
  • noble gases N 2 , Ar, He
  • the glow discharge device 11 may be a part of system 10 as illustrated in Figure 1.
  • the system may consist of the building blocks as outlined in Figures 1, 11, 12 and 13 (like Figure 3) .
  • System 10 may have a sample gas filter 13 connected to an exhaust pipe 14 at an opening 15.
  • Filter 13 may remove PM (particulate matter) and condensables from an exhaust sample 16 from exhaust 17.
  • sample 16 may flow into the vicinity of glow discharge 18 situated in a glass pipe 33 and affect the emission of the discharge according to the composition of sample 16.
  • Light 27 from discharge 18 may propagate through fibers 21, filters 22 and be converted to electrical signals by detectors 23.
  • the electrical signals may go to amplifiers and microprocessor 24 to be processed into output signals indicating the composition of sample 16.
  • Glow discharge 18 may be about 10 to 500 microns in diameter.
  • the discharge may be started and sustained with about a 100 to 400 volt AC/DC power supply in series with about a 1 to 15 Meg-ohm resistor 19, which generates the spectral band emissions shown in Figure 7.
  • Power supply 28 may be connected to metal electrode 31 via resistor 19 and to metal electrode 32.
  • the glow discharge 18 may be started and maintained between electrodes 31 and 32 due to the presence of the voltage from the power supply 28.
  • Electrodes 31 and 32 may be coated with an insulative material 46 such as, for example, MgO. Other materials may be used.
  • Optical fibers 21 may be optically connected to the glow discharge device 11 at optical interface or window
  • optical filters 22 may be deposited at the flattened ends of the optical fibers 21, which would have narrow band pass half-width of about three nm (to match the -2.8 nm NO emission half bandwidth (HBW)) to 20 nm. Also shown in Figures 1, 11 and 12, are photo detectors 23 (Si-diode, Si-photo-transistor, sensitized for UV) proximate to filters 22.
  • Outputs of the photo detectors 23 may go to amplifiers and signal processor 24 which may output a referenced signal about NO, VOC, CO, SO x , or the like in the sample 16, with a ppm indication signal at output 35 of amplifiers and processor 24.
  • device 11 may be designed to force the micro discharge 18 to glow close to and impinge on the side of the observation fibers 21, as shown in Figure 1.
  • the mild discharge 18 sputter action may be intended to maintain a high level of optical transmission of the window 25 in Figure 1, despite the known tendency of combustion exhaust gases to darken optical surfaces they come in contact with, in a short time.
  • the electrodes may be kept clean.
  • Significant elements of the system 10 in Figure 1, and other systems described herein, may include optical fiber-cables 21 with deposited filters 22 at their ends with the other ends facing the glow discharge 18, and the PM filter or filters 13.
  • Materials of these fiber and filters may include those that are low-cost, temperature resistant (not a high need due to the intermediate PM filter 13, which may cool sample gas temperatures) and of a high index, in order to minimize the angular sensitivity of the band-pass filters 22, which may be given by a few exemplary filters described in terms of
  • ⁇ ⁇ o (n e 2 - sin 2 ⁇ )°- 5 /n e .
  • ⁇ ⁇ ⁇ o + ⁇ ⁇ T, with ⁇ ⁇ 0.01- 0.2 nm/deg. C.
  • NA 0.15 for single mode fiber and 0.3 for multi-mode fibers.
  • the parts may include one grounded and one insulated wire in a tube 33 (glass, quartz, sapphire) to support the plasma in a spark-plug-like environmental package 44 as shown in Figure 3, optical fibers 21 with deposited interference filters 22, two to four Si photo-diodes 23, a power supply 28 with a DC-to-DC converter (100-400V) , an amplifier 24 for the photo-diodes 23, and a microprocessor 24 for signal processing and logic functions, a PM filter 13 and sample gas flow channels. Also, automated assembly and calibration may be implemented to reduce costs. A very little scrap would be expected from the making of the present micro-plasma sensor system 10.
  • NO x sensing via MDD may have been done by others, with noble gas purge in one micro channel leading to the MDD, but has not been done without such purge, directing only the sample gas to the MDD.
  • Features of the sensing system in Figure 1 include: operating the MDD without noble purge gas; using MDD for window cleaning and for maintaining electrode isolation in an MDD detector application; observing no spectral emissions in the IR; designing a co-planar MDD as source another MDD as detector; and co-locating a spectral-emissive and, for example, a soot sensor in one package.
  • the sensor system 10 may include use of plasma discharge device 11 for exhaust gas composition measurements, but without noble-gas purge; use of the plasma discharge 18 to keep the observation window clean, by plasma-etching away any combustion-product deposits such as condensable tars and carbon-soot; use of the same plasma discharge to maintain the required electrical insulation of the non-grounded micro-discharge electrode (see magnified view of one example electrode tip in Figure 2) ; use of a plasma discharge to maintain the required electrical insulation of the non-grounded electrode by additional periodic power-cleaning cycles, which may or may not cause a pause in the measurement and the self-check cycle; use of an associated PM filter 13 to cool and clean the sample gases after soot sensing but before spectral MDD sensing, in order to minimize temperature-induced wavelength shifts in the bandpass filter; use of smart positioning between the end
  • Additional design features related to quasi state- of-the-art PM filters may include mechanisms for overcoming concerns about water condensation (removal or made harmless via sensor heating) , and packaging the soot sensor electrode into this same housing to reduce cost, total bulkiness and plasma-cleaning synergies.
  • Another implementation of glow discharge device 11 is system 20 shown in Figure 4.
  • a scanning Fabry-Perot filter 26, shown with more detail in Figure 5, may be adapted to the band pass and wavelength range desired for the desired application.
  • a PM filtered gas 16 may enter the glow discharge device 11 and enter the vicinity of the glow discharge 18.
  • Discharge 18 may be enclosed in a glass capillary or pipe 33.
  • the discharge 18 may be started and sustained by a voltage of about 100 to 400 volts from power supply 28 connected to electrodes 31 and 32 from which the discharge emanates.
  • a light pipe 34 or other optical conveyance mechanism may be optically connected to the glass pipe 33 at a window 25 to carry the light 27 of the discharge to a non-dispersive, Fabry- Perot, narrow band-pass, scanning filter 26.
  • Filter 26 may provide a spectral analysis of the light 27.
  • Filter 26 may be a Fabry-Perot (FP) based MEMS spectrometer for MDD emission analysis.
  • Light pipe 34 may be optically coupled to a Pyrex or quartz window 36 of filter 26. Window 36 may be a UV blocking filter.
  • light 27 may propagate through window 36 into a FP cavity having about a 5 mil (25 micron) high cavity 37 with an etalon 38 that may move up or down to adjust cavity 37 to a particular frequency of interest to be passed through or filtered out .
  • the movement of etalon 38 may be effected with a control signal line 45. This adjustment may determine the wavelength of light 27 to be passed or blocked.
  • Cavity 37 may be formed with a sapphire base 38 and window 36 with an environmental hermetic seal 39 formed around the perimeter of cavity 37 to provide space in the cavity and a seal between window 36 and sapphire base 38 to seal the cavity from its environment.
  • the portion of light 27 that passes through cavity 37 may be sensed by an array of detectors 41.
  • the detectors 41 may be in a form of a linear or another kind of array, and be composed of AlGaN/GaN or other appropriate or workable material. Detectors 41 may convert the light signals 27 into electrical signals that are input into a readout integrated circuit 42. Circuit 42 may have a processor to analyze the signals to provide information about the sample gas 16. A package 43 may be utilized overall to enclose at least a portion of filter 26. The output of circuit 42 may provide a spectral analysis of light 27. This analysis may imply the composition of the sampled gas 16 passing through the glow discharge 18.
  • the ⁇ line-width band-pass may scan
  • the computed Fabry-Perot band width and spectral position (and including the response of the AlGaN detector array) for the last row in the table in Figure 9 may be shown in Figure 10 for the minimum, center and maximum wavelength position, respectively, with the corresponding etalon mirror spacing.
  • Figure 10 shows percentage of transmission versus wavelength for a wavelength scan of a MEMS FP filter.
  • the wavelength position may be limited in the computed example in Figure 10 by the available wavelength sensitivity range of the AlGaN detectors, which is about 290 to 360 nm.
  • the sensor system 20 may be based on the following: plasma micro discharge device (MDD) for gas sensing via spectral emission analysis of unknown gas mixture samples, using non-dispersive (Fabry-Perot-based) spectral analysis (rather than a dispersive spectrometric analysis) or interference filters; the plasma micro discharge device (MDD) for gas sensing via spectral emission analysis of unknown gas mixture samples, using non-dispersive (Fabry-Perot-based) spectral analysis (rather than a dispersive spectrometric analysis) or interference filters; the plasma micro discharge device (MDD) for gas sensing via spectral emission analysis of unknown gas mixture samples, using non-dispersive (Fabry-Perot-based) spectral analysis (rather than a dispersive spectrometric analysis) or interference filters; the plasma micro discharge device (MDD) for gas sensing via spectral emission analysis of unknown gas mixture samples, using non-dispersive (Fabry-Perot-based) spectral analysis (rather than a
  • Fabry-Perot (FP) wavelength scan performed via a MEMS- based FP-filter design; new use of the above assembly (of MDD and FP-based spectral filter) as high speed gas chromatography peak (GC) analyzer, and independently, as stand alone gas sensor for NO, O 2 , SO 2 , ... in one unit; new use of above assembly (MDD+FP+GC) , whereby the GC is
  • Successful implementation of systems 10 and 20 may enable the achievement of low false positive probabilities when using this discharge device 11 and detector as part of a GC-CG-MDD micro-analyzer, as represented by PHASED.
  • the sensing systems 10 and 20 may offer the following advantages over previously proposed or offered exhaust gas composition sensing systems. They are more compact, rugged and lower cost than chemiluminescence- based sensor systems. They are more stable than metal- oxide or catalyst-based and conventional optical sensor systems. They are less energy consuming than ZrO 2 -based NO and O 2 sensor systems and more temperature change tolerant than other ZrO 2 -NO/O 2 sensor systems. They are more manufacturable than multi-layer ZrO 2 , metal oxide or catalyst based sensor systems. They are compatible and easy to integrate with a soot sensor system.
  • System 30 of Figure 6 may have a discharge gap device 11, like that of systems 10 and 20, except that light 27 may be conveyed via a light pipe 34 to a dispersive spectrometer 47 for analysis of the emission of the discharge 18 to reveal information about the sample gas 16.
  • Light 27 may be conveyed to an optical grating 48 for reflection of various wavelengths of light 27 to various pixels, respectively, of a CCD light detecting array 49. Electrical signals from array 49 may go to a processor 51 for analysis and interpretation.
  • the MDD (micro discharge device) 60 of Figure 11 may generate an optical emission 56 that is characteristic of the gaseous environment around the electrodes 53 supported by a -2x2 mm silica chip, as protected from particulates of exhaust gases 65 by a screen or stainless frit 55 which may be regarded as an enclosure or housing for at least partially containing the electrodes and the light waveguide or waveguides .
  • Exhaust gases 65 may be turbulent and reach temperatures up to 1100 degrees C (2012 degrees F) .
  • MDD 60 may be housed in a spark plug type of package or housing 57 like that shown in Figure 13.
  • the housing 57 may be threaded to be in a fitting 58 having, for example, M14 threads 61. Or the fitting 58 may be formed or welded to an exhaust pipe 59 or other fixture that may have a fluid to be tested. Housing or package 57 may have a hex fitting like a nut or bolt so that the housing and package may be screwed in or out with a tool such as a wrench.
  • Fiber 63 may be a silica fiber having an outside diameter of about 20-200 microns.
  • the filters 22 may have a delta wavelength of about 2-5 nm.
  • the filtered light may proceed on to be detected by photo diodes, phototransistors or generically "light detectors" 23, on a one filter to detector basis, respectively.
  • Electrical conductors may connect the detectors 23 to terminals 115 of connector 64. Terminals 115 may be connected to a processor 24 (as shown in Figure 1, though not shown in Figures 11 and 12) .
  • a mode of failure could be via contact problems between the electrical leads 62 fed through or around the silica chip 54 and those embedded in the spark plug package 57.
  • a simple spark plug housing package 57 which includes a pair of self- supporting discharge electrodes 53, or the ends of leads 62 which may be electrodes, a discharge 56 that maintains the optical fiber 63 inlet surface 64 clean, and without a MDD silica chip 54.
  • the electrodes may be kept clean also. This cleaning of surface 64 and electrodes may occur without the presence of a noble gas.
  • the leads 62 may be extended from connector 64 to electrodes 53.
  • the length of the leads 62 and waveguide 63 may be about 10 to 40 cm.
  • Figure 12 shows another version of the sensor package, where the silica chip 54 may be eliminated, with the electrical leads 62 coming through the spark plug housing 57 and extending into the exhaust gas side of the sensor.
  • the leads 62 may be strong enough to hold their position and shape without the need of the silica chip 54 to support them.
  • There may be an alumina insulator 69 about the leads 62 and waveguide 63 within a package, housing or structure 57.
  • the separate discharge electrodes 53 which were fashioned out of deposited thin- film metal material may be dispensed with in favor of the ends of leads 62, the latter of which may be regarded as substituting electrodes 53.
  • the shape and space between the latter electrodes may be formed via mechanical cutting, shaping and bending, to result in the typical electrode shape and spacing of 10 to 30 microns, not unlike self-supporting spark-plug electrodes.
  • the ends of the leads may be regarded as electrodes 53 or 62.
  • successful system designs may cause the micro discharge 56 to glow close to and impinge on the side of the observation optical surfaces, such as those of the silica fiber 63, chip and/or window.
  • the mild discharge sputter action may be intended to maintain a high level of optical transmission of the optical transmission surface, despite the known tendency of combustion exhaust gases to darken optical surfaces they come in contact with, in a short time, due to a deposition of tarry and soot-containing materials.
  • Excessive discharge action may etch the material of surfaces close to the glow discharge, while insufficient action (i.e., power) may create deposits .
  • a capillary electrode discharge (CED) approach may be used to generate atmospheric plasmas, and surface cleaning such as the removal of organic material on glass substrates.
  • Helium or hydrogen (He or H 2 ) may be used as an ignition and discharge gas and oxygen (O 2 ) be added as a reactive gas.
  • Low frequency AC power supply with a sine wave voltage (20 kHz to 20 GHz) may be used to generate plasmas under atmospheric pressure.
  • the electrodes may be composed of a 10 micron thick capillary dielectric and have a diameter of about 300 microns. He/0 2 plasmas generated in the space of a few mm between the capillary electrode and the substrate (ground) may be uniform and very stable.
  • the optical emission spectroscopy and the I-V characteristic of the discharges may be used to characterize the capillary electrode discharges.
  • Cleaning rate of organic material on glass higher than lOOOA/min may be observed after exposure to He/0 2 plasmas.
  • Figure 14 shows a sensor system 80 having a housing or enclosure 66 with a particle suppression structure 67 having louvers, a sample gas input/output, and a swirl and cyclone separator.
  • Housing or enclosure 66 may be regarded as containing at least partially the electrodes and the light waveguide or waveguides.
  • Structure 67 may have impactor plates 68 for aiding separation of particles of fluid 65.
  • the flow of exhaust 65 through structure 67 may be induced by head pressure and venturi action, assisted by components of enclosure 66, including a 0.3 mm opening at the top of the enclosure or structure inserted in the flow of the fluid or exhaust gas 65..
  • fluid or exhaust 65 may be rather turbulent in the pipe or conveyance 59, and structure 67 may provide a way of sampling exhaust 65 for the micro discharge 56 without disrupting ' the latter for an accurate reading with sensor system 80.
  • Electrodes 53 may provide the basis for the micro discharge 56.
  • the reaction of the discharge 56 to the fluid 65 being sensed may be optically transmitted by optical fiber 63 to a light detector for conversion to electrical signals.
  • the signals might be digitized for computer processing and analyses of the fluid.
  • the light conveyed from the discharge 56 may be IR, visible and/or UV.
  • Leads or electrodes 62 and fiber 63 may be contained and structurally supported within housing 57 having a ceramic insulator 69. Electrodes 62 may be attached to connector pins 71 which may have a 0.3 mm dimension.
  • the discharge 56 may keep the electrodes and the input surface of waveguide clean without the need of noble gas purging.
  • the filters, detectors, power supply and processor associated with system 80 may similar to that of systems 60 and 70.
  • Figure 14a shows a sensor 81 having the same kind of structural and electrical parts as sensor system 80, except that the former has a housing that is somewhat different.
  • Structure 82 may have an input of fluid 65 from the sides and a procession of the fluid through a number of impactor plates and into the micro discharge 56 area, and an exit out through the end or top of housing or structure 82.
  • structure 82 may be designed to have both an input and output of fluid at the top of it.
  • Systems 60, 70, 80 and 81 may be used to sense other fluids besides exhaust gases 65.
  • Figures 16, 17, 18a and 18b show sensor configurations that expand on those in Figures 14 and 14a.
  • the preferred range of the electrode 62 gap 83 for atmospheric MDDs may be 30 to 70 microns.
  • Figure 15 details the electrode gap 83 area shown in Figure 14.
  • the shape of the two electrodes 62 at the discharge location may enable the spacing between the two electrodes to be within a desirable range, after being kept apart by the thick optical fiber 63 cladding.
  • a "hook" at the electrode 62 tips may add unacceptable cost during manufacture, and the cavity may plug up with deposits during use in a car exhaust environment.
  • Figure 16 shows an arrangement 113 that may avoid the plugging and spacing problem by using a tubular bottom electrode 84 and a (grounded) top electrode 85, with a tip 86, which lines up with the centered optical
  • the fiber 87 having a thin ( ⁇ ⁇ /2) cladding 88.
  • the fiber with the cladding may have a diameter 116 of about 70 microns.
  • the risk of 30 to 70 micron discharge gap misalignment may be high and possibly costly to overcome.
  • the gas discharge area may be represented by the two elliptical, shaded areas 89.
  • Figure 17 shows an arrangement 114 having a qualitative (not to-scale) side view of a tube-shaped optical fiber 91, where the discharge (elliptical shaded areas 92 shown to represent the cross section of a ring- shaped or annular micro discharge) occurs between the center 93 and outer 94 electrodes and over the top rim of the tube-"fiber" .
  • the tube-fiber 91 may be replaced with a number of optical fibers adjacent to each other parallel to one another to the electrodes.
  • the overall diameter of the device 114 may be about 3 mm.
  • the center electrode 93 may have a diameter of about o.5 mm.
  • the tube-fiber or optical fibers 91 may have an outside diameter of about 0.6 mm.
  • Figures 18a and 18b show arrangements 111 and 112, respectively, with a single 40 to 70 micron diameter 117 optical fiber 95 with cladding of a small thickness, and four of such fibers 95 having positions and being fastened between two larger-diameter metal electrodes 96 and 97 of about 300 to 500 microns (0.3 to 0.5 mm) in diameter. Both electrodes 96 and 97 may be anchored within the same ceramic block 69 as shown in Figure 14.
  • the discharge light 56 may be aligned with the optical fibers 95, and the assembly may be manufactured with relative ease.
  • the use of separate fibers 95 besides lending mechanical flexibility, also enables design flexibility on how to separate different wavelength channels (via band-pass filters 22 of Figure 1 or a dispersive element) .
  • Figure 19a and 19b represent two versions 101 and 102 of the sensor system related to Figures 17, 18a and 18b, with respect to capturing the discharge light 103, ease of manufacture (gap adjustment and stability, despite temperature fluctuations, via a common ceramic anchoring block) and design flexibility.
  • Version 101 shows electrodes 104 and 105 with a fiber 106 between the electrodes 104 and 105 to convey light from discharge 103 of the assembly 101.
  • the tube-shaped optical fiber 107 in Figure 19b may be broken into or replaced with a number (10 to 20) of individual fibers 108 that are positioned along a circular order or path about the central electrode 109.
  • a circular discharge 103 may be initiated between the center electrode 109 and circumferential electrode 110.
  • the circular fiber arrangement 107, 108 may convey the light from the discharge 103 of the assembly or arrangement 102.
  • Arrangement 102 may bear much resemblance to arrangement 114 of Figure 17, except that the tubular fiber 91 of arrangement 114 may be in lieu of a plurality of fibers 108 in arrangement 102.

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  • Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)

Abstract

L'invention concerne un système de capteur à micro-plasma comportant un espace de décharge luminescente formé par des électrodes. Un fluide à détecter peut être introduit dans le voisinage de la décharge, au niveau dudit espace. L'émission lumineuse produite par la décharge peut être couplée à un analyseur de spectre et/ou à un processeur, pour déterminer les propriétés du fluide. Un couplage peut comprendre un guide d'onde à proximité de l'espace de décharge. La décharge permet d'entretenir la propreté de la fenêtre et l'isolation électrique des électrodes. L'analyseur optique peut comprendre des filtres pour un ou plusieurs canaux optiques reliés aux détecteurs. Les détecteurs peuvent délivrer en sortie des signaux optiques à traiter. Les électrodes peuvent être parallèles entre elles, tout en présentant un guide d'onde optique entre elles, ou bien les électrodes peuvent être concentriques, de manière à former un espace de décharge annulaire. De la même façon, le guide d'onde optique peut être concentrique à une ou à plusieurs électrodes. Le guide d'onde peut présenter une ou plusieurs fibres optiques, ou être tubulaire.
EP05784981A 2004-08-10 2005-08-10 Systeme de capteur a micro-decharge Withdrawn EP1776579A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US10/915,577 US20050142035A1 (en) 2003-12-31 2004-08-10 Micro-discharge sensor system
PCT/US2005/028406 WO2006020702A2 (fr) 2004-08-10 2005-08-10 Systeme de capteur a micro-decharge

Publications (1)

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EP1776579A2 true EP1776579A2 (fr) 2007-04-25

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EP05784981A Withdrawn EP1776579A2 (fr) 2004-08-10 2005-08-10 Systeme de capteur a micro-decharge

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EP (1) EP1776579A2 (fr)
JP (1) JP2008510143A (fr)
WO (1) WO2006020702A2 (fr)

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US7733482B2 (en) * 2007-03-26 2010-06-08 Ruda Harry E System and method for determining at least one constituent in an ambient gas using a microsystem gas sensor
US8330955B2 (en) 2008-02-12 2012-12-11 Hewlett-Packard Development Company, L.P. Color detector
EP2243011A4 (fr) 2008-02-13 2013-12-18 Hewlett Packard Co Détecteur de couleur possédant des photodétecteurs échelonnés par zones
DE102009057130A1 (de) 2009-12-08 2011-06-09 Heinrich-Heine-Universität Düsseldorf Verfahren zur Analyse der Zusammensetzung von Gasgemischen
WO2017033708A1 (fr) * 2015-08-27 2017-03-02 オリンパス株式会社 Dispositif et système d'essai
DE102016200517A1 (de) * 2016-01-18 2017-07-20 Robert Bosch Gmbh Mikroelektronische Bauelementanordnung und entsprechendes Herstellungsverfahren für eine mikroelektronische Bauelementanordnung
CN106442475A (zh) * 2016-10-13 2017-02-22 上海交通大学 一种大气压等离子体射流检测溶液中金属离子的装置

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Publication number Publication date
WO2006020702A2 (fr) 2006-02-23
JP2008510143A (ja) 2008-04-03
WO2006020702A3 (fr) 2006-06-29

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