WO2001031326A1 - Ensemble capteur de gaz electrochimique et procede - Google Patents

Ensemble capteur de gaz electrochimique et procede Download PDF

Info

Publication number
WO2001031326A1
WO2001031326A1 PCT/GB2000/004054 GB0004054W WO0131326A1 WO 2001031326 A1 WO2001031326 A1 WO 2001031326A1 GB 0004054 W GB0004054 W GB 0004054W WO 0131326 A1 WO0131326 A1 WO 0131326A1
Authority
WO
WIPO (PCT)
Prior art keywords
electrode
sensing electrode
operational amplifier
gas
auxiliary
Prior art date
Application number
PCT/GB2000/004054
Other languages
English (en)
Inventor
John Robert Finbow
Constantine Dean Capetanopolous
Original Assignee
Sem Corporation
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 Sem Corporation filed Critical Sem Corporation
Priority to AU79359/00A priority Critical patent/AU7935900A/en
Publication of WO2001031326A1 publication Critical patent/WO2001031326A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/403—Cells and electrode assemblies
    • G01N27/404—Cells with anode, cathode and cell electrolyte on the same side of a permeable membrane which separates them from the sample fluid, e.g. Clark-type oxygen sensors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
    • G01N27/416—Systems
    • G01N27/4163—Systems checking the operation of, or calibrating, the measuring apparatus

Definitions

  • the invention relates to an electrochemical gas sensor assembly including an electrochemical gas sensor having sensing and counter electrodes, an intervening body of electrolyte contacting the electrodes, and means for controlling the diffusion of gas to the sensing electrode such as a solid membrane, gas phase or Knudsen diffusion barrier.
  • the active portions of the electrodes may face towards or away from each other.
  • Electrochemical gas sensors of this kind are well known and are used to sense a variety of gases including oxygen, and toxic gases such as hydrogen sulphide, carbon monoxide, sulphur dioxide, nitric oxide, nitrogen dioxide, etc.
  • US-A-5064516 describes a sensor in which the anode is first cleaned by maintaining the potential at a high level where all adsorbed material is removed.
  • Such sensors can have a limited lifetime or develop defects such as broken electrical connections, partially or fully blocked gas access ports by dirt or moisture condensation electrolyte leakage etc and it is important to know whether or not the sensor is still active and/or operating correctly, without necessarily having to expose it to a known concentration of gas.
  • an electrochemical gas sensor assembly comprises an electrochemical gas sensor including sensing and counter electrodes, an intervening body of electrolyte contacting the electrodes, a diffusion control for controlling the diffusion of gas to the sensing electrode wherein a gas to be sensed is reacted at the sensing electrode, the electrode being connected in an electrical circuit, the circuit including a monitor for monitoring current flow in the circuit related to the concentration of the gas being sensed, and is characterised in that the assembly further comprises an electrical biasing system operable in a test mode to bias the sensing electrode relative to the counter electrode to a potential at which oxygen is reduced at the sensing electrode and evolved at the counter electrode, the monitor providing an output indicating the operating condition of the sensor.
  • the biasing system conveniently comprises a voltage source which will typically be connected to the sensor via a switch so that it can be selectively connected by the user during the test mode .
  • the invention is applicable to two electrode sensors having a sensing electrode and a counter electrode only and also three electrode sensors in which a reference electrode is also provided.
  • the biasing system preferably includes a voltage source connectable to one input of an operational amplifier, the reference electrode being connected to the other input of the operational amplifier, and the output of the operational amplifier being connected to the counter electrode.
  • a switch is provided for connecting the one input of the operational amplifier either to the voltage source or to ground.
  • an electrochemical gas sensor assembly comprises an electrochemical gas sensor including sensing and counter electrodes, an intervening body of electrolyte contacting the electrodes, and a diffusion control for controlling the diffusion of gas to the sensing electrode wherein the gas to be sensed is reacted at the sensing electrode, the electrode being connected in an electrical circuit, the circuit including a monitor for monitoring current flow in the circuit related to the concentration of the gas being sensed, and is characterised in that the assembly further comprises an auxiliary sensing electrode; and an electrical biasing system for biasing the auxiliary sensing electrode relative to the counter electrode to a potential at which oxygen is reduced at the auxiliary electrode and evolved at the counter electrode.
  • Figure 1 is a schematic, exploded view of one possible sensor arrangement, "the planar electrode arrangement";
  • Figure 2 is a schematic, exploded view of an alternative sensor arrangement, "the stacked electrode arrangement " ;
  • Figures 3A and 3B are a plan and side elevation respectively of the planar electrode arrangement shown in Figure 1 ;
  • Figures 4A and 4B are circuit diagrams illustrating a 3 -electrode and a 2-electrode sensor operation respectively with polarisation test circuitry for checking the combination of sensing electrode and diffusion barrier;
  • Figure 5 is a circuit diagram illustrating a test circuit for checking the diffusion barrier through an auxiliary sensing electrode without polarising the sensing electrode;
  • Figure 6 illustrates a circuit for optionally selecting to test either the diffusion barrier separately through an auxiliary sensing electrode, without polarising the sensing electrode, or the combination of sensing electrode and diffusion barrier;
  • Figure 7 depicts a circuit diagram of a suitable current measuring arrangement
  • Figure 8 is a circuit diagram illustrating a further example of the processing circuit for a four electrode sensor
  • Figure 9 is a modified form of the Figure 8 example.
  • Figure 10 is a modified version of the Figure 9 example.
  • the sensor shown in Figure 1 comprises a base 1 defining an electrolyte reservoir 2. Extending out of the reservoir 2 through an aperture 3 is a hydrophilic wick 4 which conveys electrolyte to a hydrophilic separator 5 above which is positioned a reference electrode 6 supported on a porous ptfe tape 7A. A porous ptfe tape 7B forms a seal to the base 1. The wick 4 extends through the ptfe tape 7B, separator 5, reference electrode 6 and ptfe tape 7A. A separator 8 is positioned above the reference electrode and above this is positioned a counter electrode 9 supported on ptfe tape 10. The wick 4 extends through the counter electrode 9 and ptfe tape 10.
  • a separator 11 is positioned above the ptfe tape 10 and above the separator 11 is a ptfe tape 12 on the underside of which is provided a sensing electrode 13 and an auxiliary sensing electrode 14, disposed in a planar arrangement with respect to each other.
  • Each electrode 6,9,13,14 is connected to electrical circuitry to be described by respective connectors 15-18.
  • a top plate 19 having a capillary 20 defining a gas phase or Knudsen barrier is secured to the base plate 1 (by means not shown, e.g. bolting, heat sealing, ultrasonic welding etc.) and an "O" ring 21 is sandwiched between the top plate 19 and the ptfe tape 12.
  • the sensing electrode 13 is positioned preferably directly under the capillary 20. By virtue of capillary action, electrolyte is drawn out of the reservoir by the wick 4 so as to fill the region between the electrodes and to contact the electrodes.
  • electrodes 13,14 in Figure 1 The construction of electrodes 13,14 in Figure 1 is shown in more detail in Figures 3A and 3B.
  • the auxiliary sensing electrode 14 is supported on a separate porous ptfe tape 12B.
  • the electrode component is supported over the separator 11B and the wick 4 extends through electrode 14 and porous ptfe tape 12B to a separator 11A.
  • the final member of the electrode stack comprising sensing electrode 13 supported on porous ptfe tape 12A is then positioned over separator 11A as shown in Figure 2.
  • the auxiliary sensing electrode is not connected to the external measuring and control circuit and the sensing electrode is connected in a conventional manner to the external circuit.
  • Gas to be sensed diffuses through the capillary 20 and through the ptfe tape 12 (12A) where it is detected and measured by reacting electrochemically at electrode 13 to produce a current proportional to the concentration of the gas.
  • Oxygen also diffuses through the capillary 20 and then on the inside and outside of the O-ring 21 through the hydrophilic components (ptfe tapes) to the counter electrode 9. Further oxygen may diffuse to the counter electrode 9 through the aperture 3 in the base 1.
  • Figure 4A provides an example of an electrical circuit for use with a 3 -electrode sensor in which the sensing electrode 13 performs the dual function of measurement electrode in normal operation and test electrode in check or test mode.
  • the sensing electrode 13 is connected to a current monitor 23 which in turn is connected to ground.
  • a 2 pole switch 24A in position (a) connects the input of an operational amplifier 22 to ground.
  • the reference electrode 6 is connected to the other input of the operational amplifier 22 and the counter electrode 9 is connected to the output of the operational amplifier 22. In the normal mode therefore the response to gas to be measured is determined by means of this potentiostatic circuit including operational amplifier 22 in a conventional manner.
  • the switch 24A In test mode the sensor test gas is removed and the switch 24A is changed to position (b) to apply a polarising voltage from a voltage source 26 into the input of the operational amplifier 22.
  • This applied voltage is selected to cause the sensing electrode to operate at a potential at which it reduces oxygen from the ambient air, in a diffusion limited mode whereby the oxygen reduction current is governed by the capillary diffusion barrier 20 of the gas sensor:
  • the value of the limiting current generated by this reaction provides a check that all functions of the sensor are operating correctly and for example the capillary is neither fully nor partially blocked and that the sensing electrode is functioning correctly.
  • the cell balance is maintained by an electrochemical process of oxygen evolution at the counter electrode by which the current flows through the sensor from the output of the operational amplifier:
  • a current monitor 25 can be alternatively located in the output feedback loop of the operational amplifier instead of sensing to ground connection monitor 23.
  • Oxygen evolved at the counter electrode will dissipate out through the aperture 3 in the base 1 and if necessary well known steps can be taken to prevent that oxygen reaching the sensing electrode 13.
  • Figure 4B depicts a circuit which can effect the same measurement as Figure 4A when a 2 -electrode electrochemical sensor is employed.
  • the counter electrode 9 effectively acts as both reference and counter electrode, the counter electrode 9 being connected to both the output and an input of the operational amplifier 22.
  • Figure 5 depicts an alternative mode of operation in which the auxiliary sensing electrode 14 is used in test mode to generate the oxygen reduction current, rather than the sensor's sensing electrode 13 itself.
  • This mode can be used whenever it is required to test the sensor without perturbing the sensing electrode 13.
  • This method of operation does not test the functionality of the sensing electrode 13.
  • the switch 24A is replaced with a 3 -way, double pole ganged switch 24B.
  • the normal mode of operation is achieved with the switch 24B in positions a : , a 2 , a 3 in which the auxiliary electrode 14 and voltage source 26 are disconnected from the potentiostatic circuit and sensing electrode 13 and the inputs to the operational amplifier 22 are both connected to the common earth.
  • FIG. 6 depicts an arrangement whereby it is possible to select all three modes of operation or test using a 3- way, 3 -pole ganged switch 24C.
  • the sensing electrode 13 is connected in a conventional manner to the potentiostatic circuit when the sensor acts in a normal way to measure the gas to be detected; auxiliary electrode 14 and voltage source 26 are isolated from the circuit.
  • the voltage source 26 provides a polarising potential at the sensing electrode 13 generating an oxygen reduction current to test the functionality of the sensing electrode and diffusion barrier combination; the auxiliary electrode 14 remains isolated.
  • c 3 voltage source 26 provides a polarising potential at the auxiliary electrode 14 and the resulting oxygen reduction current tests the integrity of the diffusion barrier 20; the sensing electrode 13 is isolated.
  • the current monitor 23 can take any conventional form and one suitable circuit is shown in Figure 7. In this case, the sensing electrode 13 (or auxiliary electrode 14) is connected to one input of an operational amplifier 27 having a feedback resistor 28. The other input of the operational amplifier 27 is connected to ground.
  • the output from the operational amplifier 27 is a voltage V which can be used to determine the current flow from the sensing electrode 13 (or auxiliary electrode 14) using Ohms Law.
  • Figure 8 shows a circuit that may be used to provide a test of the sensor functions except for the sensing electrode or the sensor functions and sensing electrode without either perturbing the sensing electrode or isolating it from the potentiostatic measurement and control circuit .
  • the sensing electrode 13 is constantly connected to the main instrument potentiostatic control and measurement circuit driven in a conventional way by operational amplifier 22, reference electrode 6, counter electrode 9 and current monitor 23, for measuring the current generated at the sensing electrode 13 by the gas to be detected.
  • a double pole, three way, ganged switch 31 in position a lf a 2 isolates the auxiliary electrode 14 from the main instrument potentiostatic control and measurement circuit during normal measurement mode of the sensor.
  • a polarising current is applied -to the auxiliary electrode 14 by means of the circuit shown in Figure 8, incorporating an operational amplifier 29; the auxiliary electrode 14 is connected to one input of the amplifier 29 and a voltage source 26A is connected to the other input of the amplifier through switch 31.
  • the voltage source 26A is selected to control the auxiliary electrode 14 at a potential at which it undergoes electrochemical reduction of oxygen from the ambient air:
  • Resistor 30 in the feedback circuit of amplifier 29 provides a means of measurement of this current between the amplifier 29 output and earth by means of Ohms Law:
  • 1 A is the auxiliary electrode current.
  • the value of this current provides a measure of the integrity of the sensor without perturbing the normal operation of the sensing electrode.
  • the current flowing in the feedback loop of operational amplifier 22, and given by current measuring device 25 is the sum of the auxiliary and sensing electrode currents.
  • a second test mode switch 31 is turned to position c lf c 2 which selects a second input voltage source 26B to the input of amplifier 29, isolating voltage source 26A.
  • the voltage source 26B is chosen to operate the auxiliary electrode 14 at a potential whereby it both reduces oxygen from the ambient air by electrochemical reaction and evolves hydrogen at the auxiliary electrode:
  • the hydrogen evolved is permitted to diffuse to sensing electrode 13 which responds to hydrogen by electrochemical oxidation:
  • Figure 9 illustrates a modified form of the Figure 8 circuit in which the voltage source 26B and the switch 31 are omitted for use when monitoring toxic gases in ambient air.
  • the voltage source 26A is connected permanently to the operational amplifier 29.
  • the effect of this arrangement is that the auxiliary electrode 14 is being operated simultaneously with normal operation of the sensing electrode 13 so as to provide a continuous check for correct operation of the sensor.
  • the Figure 9 arrangement could also be used when monitoring flue gasses but in this case, due to the variation in oxygen concentration, it would need to be combined either with another oxygen sensor which could monitor the oxygen concentration or the system could be periodically purged with air.
  • the latter case provides a combined oxygen/CO sensor when presented with flue gas (CO measurement from the sensing electrode and oxygen from the auxiliary) , and a self-check of the sensor from the auxiliary current during the air purge cycle .
  • a drawback of the arrangement of Figures 8 and 9 is that the sensor has four outputs corresponding to the four electrodes whereas conventional sensors only have three. This can be avoided by modifying the sensor construction as shown in Figure 10.
  • the output from the operational amplifier 29 (which indicates whether or not the sensor is operating correctly) is supplied to the input of a microprocessor 40 located on a chip within the central housing and including an A/D convertor.
  • the microprocessor is programmed to compare the input signal from the operational amplifier 29 with a predetermined, stored threshold which is exceeded when the sensor is operating normally. However, if the threshold is not exceeded, the microprocessor 40 outputs a periodic voltage signal which is supplied to the counter electrode 9 so as to impose a modulation on the normal output signal from the sensing electrode 13.
  • the output signal of the microprocessor 40 is of sufficient magnitude to cause the normal output signal from the sensing electrode 13 to vary between zero and an over range condition. This modulation can be observed by the user to detect that the sensor is not operating correctly. It will be appreciated that with the incorporation of the microprocessor 40 and by including the voltage source 26A and operational amplifier 29 within the central housing, the whole sensor will have the same form and dimensions as a conventional sensor and can be retrofitted. In the example just described, the microprocessor 40 is assumed to include its own on-board or separate power supply although this could be theoretically provided by the potentiostatic circuit itself.
  • microprocessor 40 could be replaced by an FET switch or the like in combination with a comparator and oscillator.
  • an FET switch could be inserted into the output line of sensing electrode 13 with its gate coupled to the output of the operational amplifier 29.
  • the circuits of Figures 9 and 10 could be additionally operated in a dual mode manner such that in a first mode the auxiliary oxygen current continuously checks all aspects of the sensor except the sensing electrode and in the second mode, by periodically biassing the auxiliary electrode to evolve hydrogen, additionally checks the sensing electrode integrity.
  • any or all of the switches can be electronic switches .
  • the sensing electrode in normal operating status can be oxidising or reducing the target gas, as necessary. When in the test mode, it is required to reduce oxygen, which demands a particular potential range. Oxygen evolution at the counter then completes the "pump" action of the device.

Abstract

La présente invention concerne un ensemble capteur de gaz électrochimique qui comprend des électrodes de captage et de comptage (13, 9), un corps intermédiaire d'électrolyte en contact avec les électrodes, une commande (20) de diffusion destinée à commander la diffusion du gaz vers l'électrode de captage où on fait réagir un gaz à capter au niveau de l'électrode (13) de captage, cette électrode étant connectée à un circuit électrique, lequel circuit comprend un appareil de surveillance (23) destiné à surveiller le flux de courant dans ce circuit, qui est corrélé à la concentration de gaz capté. Cet ensemble comprend aussi un système (22, 26) de polarisation électrique qu'on peut faire fonctionner en mode essai de façon à polariser l'électrode de captage (13) par rapport à l'électrode de comptage (9) à un potentiel pour lequel l'oxygène est réduit au niveau de l'électrode de captage et émis au niveau de l'électrode de comptage, l'appareil de surveillance fournissant une sortie indiquant le mode de fonctionnement du capteur.
PCT/GB2000/004054 1999-10-28 2000-10-20 Ensemble capteur de gaz electrochimique et procede WO2001031326A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU79359/00A AU7935900A (en) 1999-10-28 2000-10-20 Electrochemical gas sensor assembly and method

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9925591.1 1999-10-28
GBGB9925591.1A GB9925591D0 (en) 1999-10-28 1999-10-28 Electrochemical gas sensor assembly

Publications (1)

Publication Number Publication Date
WO2001031326A1 true WO2001031326A1 (fr) 2001-05-03

Family

ID=10863593

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2000/004054 WO2001031326A1 (fr) 1999-10-28 2000-10-20 Ensemble capteur de gaz electrochimique et procede

Country Status (3)

Country Link
AU (1) AU7935900A (fr)
GB (1) GB9925591D0 (fr)
WO (1) WO2001031326A1 (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1179731A2 (fr) * 2000-08-01 2002-02-13 Riken Keiki Co., Ltd. Capteur de gas galvanique avec une contre-électrode qui reduit oxygène
WO2003001191A2 (fr) * 2001-06-26 2003-01-03 Zellweger Analytics Limited Surveillance des capteurs de gaz
EP2581735A1 (fr) * 2011-10-11 2013-04-17 Life Safety Distribution AG Électrodes de diffusion de gaz auxiliaire pour diagnostics de capteurs de gaz électrochimiques
EP2581734A3 (fr) * 2011-10-11 2013-08-21 Life Safety Distribution AG Micro-électrodes auxiliaires pour les diagnostics de capteurs de gaz électrochimiques
EP3211411A1 (fr) * 2016-02-24 2017-08-30 Mettler-Toledo GmbH Sonde de mesure isfet et circuit de mesure pour la sonde de mesure isfet et procede
EP3712604A1 (fr) * 2019-03-18 2020-09-23 Honeywell International Inc. Systèmes et procédés de mesure de contenu d'électrolyte dans un capteur de gaz électrochimique
US10876992B2 (en) 2015-07-22 2020-12-29 Honeywell International Inc. Wicking channels
US10948452B2 (en) 2015-08-24 2021-03-16 Honeywell International Inc. Sensing electrode oxygen control in an oxygen sensor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1981002831A1 (fr) * 1980-04-11 1981-10-15 Radiometer As Dispositif et procede de mesure de la pression partielle de l'oxygene et d'un gaz qui en solution aqueuse produit une base ou un acide
US4681673A (en) * 1984-10-29 1987-07-21 General Electric Company Portable oxygen sensor with shortened break-in time
US5064516A (en) * 1987-07-16 1991-11-12 Gas Research Institute Measuring gas levels

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1981002831A1 (fr) * 1980-04-11 1981-10-15 Radiometer As Dispositif et procede de mesure de la pression partielle de l'oxygene et d'un gaz qui en solution aqueuse produit une base ou un acide
US4681673A (en) * 1984-10-29 1987-07-21 General Electric Company Portable oxygen sensor with shortened break-in time
US5064516A (en) * 1987-07-16 1991-11-12 Gas Research Institute Measuring gas levels

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1179731A2 (fr) * 2000-08-01 2002-02-13 Riken Keiki Co., Ltd. Capteur de gas galvanique avec une contre-électrode qui reduit oxygène
EP1179731A3 (fr) * 2000-08-01 2002-03-06 Riken Keiki Co., Ltd. Capteur de gas galvanique avec une contre-électrode qui reduit oxygène
WO2003001191A2 (fr) * 2001-06-26 2003-01-03 Zellweger Analytics Limited Surveillance des capteurs de gaz
WO2003001191A3 (fr) * 2001-06-26 2003-05-01 Zellweger Analytics Ltd Surveillance des capteurs de gaz
US7794575B2 (en) 2001-06-26 2010-09-14 Honeywell Analytics Limited Monitoring of gas sensors
US9689833B2 (en) 2011-10-11 2017-06-27 Life Safety Distribution Ag Auxiliary micro-electrodes for diagnostics of electrochemical gas sensors
EP2581734A3 (fr) * 2011-10-11 2013-08-21 Life Safety Distribution AG Micro-électrodes auxiliaires pour les diagnostics de capteurs de gaz électrochimiques
US9377435B2 (en) 2011-10-11 2016-06-28 Honeywell International Inc. Auxiliary gas diffusion electrodes for diagnostics of electrochemical gas sensors
EP2581735A1 (fr) * 2011-10-11 2013-04-17 Life Safety Distribution AG Électrodes de diffusion de gaz auxiliaire pour diagnostics de capteurs de gaz électrochimiques
US11085896B2 (en) 2011-10-11 2021-08-10 Life Safety Distribution Gmbh Auxiliary micro-electrodes for diagnostics of electrochemical gas sensors
US10876992B2 (en) 2015-07-22 2020-12-29 Honeywell International Inc. Wicking channels
US10948452B2 (en) 2015-08-24 2021-03-16 Honeywell International Inc. Sensing electrode oxygen control in an oxygen sensor
EP3211411A1 (fr) * 2016-02-24 2017-08-30 Mettler-Toledo GmbH Sonde de mesure isfet et circuit de mesure pour la sonde de mesure isfet et procede
US10197528B2 (en) 2016-02-24 2019-02-05 Mettler-Toledo Gmbh ISFET measuring probe, measurement circuit for the ISFET measuring probe, and method
EP3712604A1 (fr) * 2019-03-18 2020-09-23 Honeywell International Inc. Systèmes et procédés de mesure de contenu d'électrolyte dans un capteur de gaz électrochimique
US11307167B2 (en) 2019-03-18 2022-04-19 Honeywell International Inc. Systems and methods for measuring electrolyte content in an electrochemical gas sensor

Also Published As

Publication number Publication date
GB9925591D0 (en) 1999-12-29
AU7935900A (en) 2001-05-08

Similar Documents

Publication Publication Date Title
EP0990895B1 (fr) Capteur de gaz avec des membranes conductrices électriques hydrophobes
EP0744620B1 (fr) Assemblage d'un capteur de gaz
US8317998B2 (en) Methods of operation of electrochemical gas sensors
US7017386B2 (en) Self-testing and self-calibrating detector
US6370940B2 (en) Apparatus for determining concentration of a gas
US7073368B2 (en) Calibration device for gas sensors
US11085896B2 (en) Auxiliary micro-electrodes for diagnostics of electrochemical gas sensors
US20030145644A1 (en) Self-calibrating carbon monoxide detector and method
US9128045B2 (en) Electrochemical sensor with zero calibration feature and method of calibrating
EP0886776A1 (fr) Detecteur electrochimique
US20050100478A1 (en) Self-testing gas detector
US9057690B2 (en) Device for monitoring an electrochemical gas sensor
US9377435B2 (en) Auxiliary gas diffusion electrodes for diagnostics of electrochemical gas sensors
WO2001031326A1 (fr) Ensemble capteur de gaz electrochimique et procede
GB2364779A (en) Toxic gas sensor with monitoring of diffusion barrier
US6447659B1 (en) Intrinsic shorting link for gas sensors
US20120006692A1 (en) Solid electrolyte gas sensor for measuring various gas species
US20020125131A1 (en) Micro-fuel cell sensor apparatus and method for modeling the sensor response time
US6635160B1 (en) Gas sensor
EP0993608A1 (fr) Detecteur electrique approchant du comportement d'une reponse de dose et son procede d'utilisation
JP5276604B2 (ja) 電気化学式センサの診断方法及び電気化学式センサ
JP4570094B2 (ja) ガス検出装置及びこのガス検出装置に用いるガスセンサ制御回路
JP2003166971A (ja) 電気化学式ガスセンサ
JPH06186200A (ja) 酸素濃度検知装置

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BY BZ CA CH CN CR CU CZ DE DK DM DZ EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MA MD MG MK MN MW MX MZ NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT TZ UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW MZ SD SL SZ TZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: JP