US20050158457A1 - Sensor for determining gases and method for manufacturing the sensor - Google Patents
Sensor for determining gases and method for manufacturing the sensor Download PDFInfo
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- US20050158457A1 US20050158457A1 US11/000,387 US38704A US2005158457A1 US 20050158457 A1 US20050158457 A1 US 20050158457A1 US 38704 A US38704 A US 38704A US 2005158457 A1 US2005158457 A1 US 2005158457A1
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- 238000000034 method Methods 0.000 title claims description 8
- 238000004519 manufacturing process Methods 0.000 title claims description 3
- 239000007789 gas Substances 0.000 title description 17
- 229920000642 polymer Polymers 0.000 claims abstract description 30
- 239000000203 mixture Substances 0.000 claims abstract 6
- 239000000758 substrate Substances 0.000 claims description 8
- 239000002253 acid Substances 0.000 claims description 6
- 239000000919 ceramic Substances 0.000 claims description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 4
- 229910000457 iridium oxide Inorganic materials 0.000 claims description 4
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 claims description 3
- 239000001856 Ethyl cellulose Substances 0.000 claims description 3
- 235000019325 ethyl cellulose Nutrition 0.000 claims description 3
- 229920001249 ethyl cellulose Polymers 0.000 claims description 3
- 239000010970 precious metal Substances 0.000 claims description 3
- 229910021529 ammonia Inorganic materials 0.000 claims description 2
- HTXDPTMKBJXEOW-UHFFFAOYSA-N dioxoiridium Chemical compound O=[Ir]=O HTXDPTMKBJXEOW-UHFFFAOYSA-N 0.000 claims description 2
- 239000002003 electrode paste Substances 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- BDHFUVZGWQCTTF-UHFFFAOYSA-N sulfonic acid Chemical compound OS(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-N 0.000 claims description 2
- 238000000151 deposition Methods 0.000 claims 2
- 238000010438 heat treatment Methods 0.000 claims 1
- 229920005588 metal-containing polymer Polymers 0.000 claims 1
- 150000003856 quaternary ammonium compounds Chemical class 0.000 claims 1
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 19
- 239000010410 layer Substances 0.000 description 17
- 229910002092 carbon dioxide Inorganic materials 0.000 description 11
- 239000001569 carbon dioxide Substances 0.000 description 8
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 230000002378 acidificating effect Effects 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 229910052709 silver Inorganic materials 0.000 description 5
- 239000004332 silver Substances 0.000 description 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 4
- 230000035945 sensitivity Effects 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000011195 cermet Substances 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 239000000499 gel Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229910001925 ruthenium oxide Inorganic materials 0.000 description 2
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 2
- 229910052815 sulfur oxide Inorganic materials 0.000 description 2
- ZXSQEZNORDWBGZ-UHFFFAOYSA-N 1,3-dihydropyrrolo[2,3-b]pyridin-2-one Chemical compound C1=CN=C2NC(=O)CC2=C1 ZXSQEZNORDWBGZ-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 229910021607 Silver chloride Inorganic materials 0.000 description 1
- WPMWEFXCIYCJSA-UHFFFAOYSA-N Tetraethylene glycol monododecyl ether Chemical compound CCCCCCCCCCCCOCCOCCOCCOCCO WPMWEFXCIYCJSA-UHFFFAOYSA-N 0.000 description 1
- YJZATOSJMRIRIW-UHFFFAOYSA-N [Ir]=O Chemical class [Ir]=O YJZATOSJMRIRIW-UHFFFAOYSA-N 0.000 description 1
- ROZSPJBPUVWBHW-UHFFFAOYSA-N [Ru]=O Chemical class [Ru]=O ROZSPJBPUVWBHW-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- 239000012298 atmosphere Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229940075397 calomel Drugs 0.000 description 1
- 229910010293 ceramic material Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- ZOMNIUBKTOKEHS-UHFFFAOYSA-L dimercury dichloride Chemical compound Cl[Hg][Hg]Cl ZOMNIUBKTOKEHS-UHFFFAOYSA-L 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 239000000017 hydrogel Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 239000010948 rhodium Substances 0.000 description 1
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 1
- 150000003378 silver Chemical class 0.000 description 1
- ADZWSOLPGZMUMY-UHFFFAOYSA-M silver bromide Chemical compound [Ag]Br ADZWSOLPGZMUMY-UHFFFAOYSA-M 0.000 description 1
- 229910001958 silver carbonate Inorganic materials 0.000 description 1
- LKZMBDSASOBTPN-UHFFFAOYSA-L silver carbonate Substances [Ag].[O-]C([O-])=O LKZMBDSASOBTPN-UHFFFAOYSA-L 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 125000005207 tetraalkylammonium group Chemical group 0.000 description 1
- 150000005622 tetraalkylammonium hydroxides Chemical class 0.000 description 1
- DCFYRBLFVWYBIJ-UHFFFAOYSA-M tetraoctylazanium;hydroxide Chemical compound [OH-].CCCCCCCC[N+](CCCCCCCC)(CCCCCCCC)CCCCCCCC DCFYRBLFVWYBIJ-UHFFFAOYSA-M 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
Images
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
- G01N27/416—Systems
- G01N27/4166—Systems measuring a particular property of an electrolyte
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/0004—Gaseous mixtures, e.g. polluted air
- G01N33/0009—General constructional details of gas analysers, e.g. portable test equipment
- G01N33/0027—General constructional details of gas analysers, e.g. portable test equipment concerning the detector
- G01N33/0036—Specially adapted to detect a particular component
- G01N33/004—Specially adapted to detect a particular component for CO, CO2
Definitions
- Optical sensors for determining the carbon dioxide content of the air are used, among other things, in fire detectors. Their function is based on the fact that a layer sensitive to carbon dioxide changes color reversibly upon contact with the gas to be determined. This change of color is monitored by a detector, and when a predetermined minimum concentration is exceeded, an alarm is triggered. This measuring method is relatively susceptible to contamination.
- Optical CO 2 gas sensors normally are made up of a polymeric matrix, e.g. ethylcellulose, a softener and solutizer, e.g. Brij 30, and a basic gas acceptor, e.g. tetraoctylammonium hydroxide.
- a polymeric matrix e.g. ethylcellulose
- softener and solutizer e.g. Brij 30
- a basic gas acceptor e.g. tetraoctylammonium hydroxide
- U.S. Pat. No. 6,241,873 describes a carbon dioxide sensor which detects the carbon dioxide content of a surrounding atmosphere in a potentiometric manner. It features a measuring electrode and a reference electrode, which are applied on a substrate.
- the measuring electrode takes the form of a silver/silver carbonate electrode.
- the potential of this electrode is a direct function of the carbon dioxide concentration of the surroundings.
- a disadvantage of this measuring method is the fact that carbonate-containing electrodes are affected by weather influences and thus have only a low stability. Furthermore, the sensor is limited to measuring carbon dioxide.
- the present invention is based on the objective of providing a gas sensor for determining different gases in a potentiometric and/or optical manner, which has a high stability and at the same time a high sensitivity.
- a further objective lies in the compensation of the moisture-dependency of the sensor.
- the sensor according to the present invention has the advantage that its electrodes are stable over the long term and that its measuring electrode has a high sensitivity with respect to the gas to be determined. This is achieved in that a pH-sensitive electrode is used that detects the pH value of a surrounding polymer. Such pH electrodes have a sufficiently long service life and allow for the determination of various acidic and basic gases.
- the senor can be designed in such a way that, in addition to measuring the pH value, the optical absorption and the conductivity can be measured as well.
- An iridium oxide electrode is particularly suited as a measuring electrode since it is especially robust with respect to environmental influences and does not have to be provided in a pre-expanded state as do comparable glass electrodes.
- the senor includes a polymer that has a base or an acid since this results in a quick and effective absorption of the acidic or basic gas to be determined. This further raises the sensitivity and lowers the response time of the sensor.
- FIG. 1 shows a schematic representation of an exemplary embodiment of the sensor according to the present invention in top view.
- FIG. 2 shows a sectional view through the sensor represented in FIG. 1 along the sectional line A-A.
- FIG. 3 shows a schematic representation of another exemplary embodiment of the sensor according to the present invention.
- Sensor 10 represented in FIGS. 1 and 2 includes a substrate 12 preferably made of a ceramic material such as aluminum oxide for example.
- a measuring electrode 14 preferably in the form of a so-called interdigital electrode, is provided. This forms a comb-like structure.
- a reference electrode 16 is situated on the substrate which preferably also takes the form of an interdigital electrode, the extensions of comb-like reference electrode 16 engaging with the extensions of the comb-like measuring electrode 14 . This ensures a small distance between the measuring electrode 14 and the reference electrode 16 and thus a low impedance of the sensor and at the same time a large electrode surface.
- Electrodes 14 , 16 are connected to contact surfaces 18 , 20 via circuit traces 22 , 24 , which are preferably formed by a precious metal-containing hardenable resin such as for example a silver-containing epoxy resin.
- Electrodes 14 , 16 are preferably coated completely by a gas-sensitive and gas-permeable polymer layer 26 , which functions as an electrolyte and which is represented in FIG. 1 as a dashed region.
- Polymer layer 26 forms a matrix in which there are the compounds responsible for the sensitivity of the sensor.
- polymer layer 26 is made of a hydrogel or an ethylcellulose gel. Water is irreversibly bound in these gels.
- the mode of operation of the sensor is based on the fact that a gas to be determined, for example carbon dioxide, is absorbed by polymer layer 26 .
- the gas dissolves in the bound water of polymer layer 26 and changes the pH value of the latter.
- a pH sensitive electrode is used as measuring electrode 14 , the change of the pH value results in a change of the potential at measuring electrode 14 .
- the change in potential can be measured as a changing voltage between measuring electrode 14 and reference electrode 16 .
- Measuring electrode 14 can take on any specific embodiment that is suited for detecting a change in the pH value of the surroundings with sufficient precision.
- conductive metal oxide pH electrodes that have for example a surface layer of mixed iridium oxides (IrO 2 ) or ruthenium oxides (RuO x ).
- IrO 2 mixed iridium oxides
- RuO x ruthenium oxides
- platinum and rhodium electrodes are suitable as well.
- FIG. 3 shows another possible specific embodiment of the sensor according to the present invention.
- the moisture content can be determined by measuring the conductivity of the polymer film. Since the signal for the CO 2 concentration is a function of the moisture content, by also taking the moisture content into consideration, this system is able to determine the CO 2 content more exactly, i.e. without the influence of moisture.
- the construction shown in FIG. 3 is used for this purpose.
- the voltage drop U produced by the potential difference of the sensor is measured.
- the two switches 30 , 32 it is possible to determine the conductivity or the resistance of the sensor element by applying a voltage (DC or AC voltage) and by measuring the current flowing through.
- a voltage DC or AC voltage
- the latter In order to be able to absorb acidic gases—that is, gases such as carbon dioxide, nitrogen oxides or sulfur oxides which in contact with water result in an acidic solution—as quickly as possible and in sufficient quantity in polymer layer 26 , the latter preferably contains a strong base such as tetraalkyl ammonium hydroxides or tetraalkyl ammonium hydrogen carbonates. These increase the solubility of the acidic gases in water that is bound in polymer layer 26 by removing the acid produced in the dissolving process.
- a strong base such as tetraalkyl ammonium hydroxides or tetraalkyl ammonium hydrogen carbonates.
- an acid such as a sulphonic acid, for example, is preferably added to polymer layer 26 .
- This promotes the solubility of basic gases in polymer layer 26 .
- polymer layer 26 may contain homogenization agents such as tensides for example.
- an electrode paste preferably containing ceramic and metallic components, a so-called cermet, is applied onto substrate 12 and is sintered with the ceramic substrate 12 .
- Polymer layer 26 is applied onto the electrode set-up in that a solution containing the polymer, a base or acid and other additives is deposited or imprinted and the solvent is removed.
- the polymer layer has a layer thickness of 10 to 100 ⁇ m, preferably between 20 and 40 ⁇ m.
- Electrodes 14 , 16 are contacted via circuit traces 22 , 24 , which are either formed also as cermet in one step together with electrodes 14 , 16 or by imprinting a solution containing a hardenable resin and a precious-metal component and subsequent hardening of the solution.
- a silver-containing epoxy resin is preferred.
- the present invention is not limited to the exemplary embodiment described, but other specific embodiments in addition to the sensor described are conceivable as well.
- an activated carbon layer can be provided on polymer layer 26 to prevent the entry of gases that damage polymer layer 26 such as nitrogen oxides or sulfur oxides.
- a temperature measuring unit may be additionally provided for compensating temperature influences on the measured potential differences.
Abstract
A sensor for determining the concentration of a gas in gas mixtures, which has a measuring and a reference electrode as well as a polymer layer, which is in contact with the gas mixture and with the measuring electrode. A pH sensitive electrode is provided as the measuring electrode.
Description
- Optical sensors for determining the carbon dioxide content of the air are used, among other things, in fire detectors. Their function is based on the fact that a layer sensitive to carbon dioxide changes color reversibly upon contact with the gas to be determined. This change of color is monitored by a detector, and when a predetermined minimum concentration is exceeded, an alarm is triggered. This measuring method is relatively susceptible to contamination.
- Optical CO2 gas sensors normally are made up of a polymeric matrix, e.g. ethylcellulose, a softener and solutizer,
e.g. Brij 30, and a basic gas acceptor, e.g. tetraoctylammonium hydroxide. The sensor signal reveals a dependency on the moisture content of the surroundings. - U.S. Pat. No. 6,241,873 describes a carbon dioxide sensor which detects the carbon dioxide content of a surrounding atmosphere in a potentiometric manner. It features a measuring electrode and a reference electrode, which are applied on a substrate. The measuring electrode takes the form of a silver/silver carbonate electrode. The potential of this electrode is a direct function of the carbon dioxide concentration of the surroundings. A disadvantage of this measuring method is the fact that carbonate-containing electrodes are affected by weather influences and thus have only a low stability. Furthermore, the sensor is limited to measuring carbon dioxide.
- The present invention is based on the objective of providing a gas sensor for determining different gases in a potentiometric and/or optical manner, which has a high stability and at the same time a high sensitivity.
- A further objective lies in the compensation of the moisture-dependency of the sensor.
- The sensor according to the present invention has the advantage that its electrodes are stable over the long term and that its measuring electrode has a high sensitivity with respect to the gas to be determined. This is achieved in that a pH-sensitive electrode is used that detects the pH value of a surrounding polymer. Such pH electrodes have a sufficiently long service life and allow for the determination of various acidic and basic gases.
- Thus, for example, the sensor can be designed in such a way that, in addition to measuring the pH value, the optical absorption and the conductivity can be measured as well.
- An iridium oxide electrode is particularly suited as a measuring electrode since it is especially robust with respect to environmental influences and does not have to be provided in a pre-expanded state as do comparable glass electrodes.
- In a particularly advantageous embodiment, the sensor includes a polymer that has a base or an acid since this results in a quick and effective absorption of the acidic or basic gas to be determined. This further raises the sensitivity and lowers the response time of the sensor.
-
FIG. 1 shows a schematic representation of an exemplary embodiment of the sensor according to the present invention in top view. -
FIG. 2 shows a sectional view through the sensor represented inFIG. 1 along the sectional line A-A. -
FIG. 3 shows a schematic representation of another exemplary embodiment of the sensor according to the present invention. -
Sensor 10 represented inFIGS. 1 and 2 includes asubstrate 12 preferably made of a ceramic material such as aluminum oxide for example. On top of this, ameasuring electrode 14, preferably in the form of a so-called interdigital electrode, is provided. This forms a comb-like structure. Furthermore, areference electrode 16 is situated on the substrate which preferably also takes the form of an interdigital electrode, the extensions of comb-like reference electrode 16 engaging with the extensions of the comb-like measuringelectrode 14. This ensures a small distance between themeasuring electrode 14 and thereference electrode 16 and thus a low impedance of the sensor and at the same time a large electrode surface. A conventional silver/silver chloride electrode is used as a reference electrode, although other electrodes of constant potential such as calomel, antimony or silver/silver bromide electrodes are suitable as well.Electrodes contact surfaces 18, 20 viacircuit traces 22, 24, which are preferably formed by a precious metal-containing hardenable resin such as for example a silver-containing epoxy resin. -
Electrodes permeable polymer layer 26, which functions as an electrolyte and which is represented inFIG. 1 as a dashed region.Polymer layer 26 forms a matrix in which there are the compounds responsible for the sensitivity of the sensor. In a preferred embodiment,polymer layer 26 is made of a hydrogel or an ethylcellulose gel. Water is irreversibly bound in these gels. - The mode of operation of the sensor is based on the fact that a gas to be determined, for example carbon dioxide, is absorbed by
polymer layer 26. The gas dissolves in the bound water ofpolymer layer 26 and changes the pH value of the latter. Since a pH sensitive electrode is used as measuringelectrode 14, the change of the pH value results in a change of the potential at measuringelectrode 14. The change in potential can be measured as a changing voltage between measuringelectrode 14 andreference electrode 16. Measuringelectrode 14 can take on any specific embodiment that is suited for detecting a change in the pH value of the surroundings with sufficient precision. Especially suited are conductive metal oxide pH electrodes that have for example a surface layer of mixed iridium oxides (IrO2) or ruthenium oxides (RuOx). However, platinum and rhodium electrodes are suitable as well. -
FIG. 3 shows another possible specific embodiment of the sensor according to the present invention. The moisture content can be determined by measuring the conductivity of the polymer film. Since the signal for the CO2 concentration is a function of the moisture content, by also taking the moisture content into consideration, this system is able to determine the CO2 content more exactly, i.e. without the influence of moisture. The construction shown inFIG. 3 is used for this purpose. - At a high-
impedance resistor 28, the voltage drop U produced by the potential difference of the sensor is measured. Alternatively, by switching the twoswitches electrodes - In order to be able to absorb acidic gases—that is, gases such as carbon dioxide, nitrogen oxides or sulfur oxides which in contact with water result in an acidic solution—as quickly as possible and in sufficient quantity in
polymer layer 26, the latter preferably contains a strong base such as tetraalkyl ammonium hydroxides or tetraalkyl ammonium hydrogen carbonates. These increase the solubility of the acidic gases in water that is bound inpolymer layer 26 by removing the acid produced in the dissolving process. - For determining gases that react in a basic manner such as ammonia, an acid such as a sulphonic acid, for example, is preferably added to
polymer layer 26. This promotes the solubility of basic gases inpolymer layer 26. Moreover,polymer layer 26 may contain homogenization agents such as tensides for example. - For
manufacturing sensor 10, an electrode paste preferably containing ceramic and metallic components, a so-called cermet, is applied ontosubstrate 12 and is sintered with theceramic substrate 12.Polymer layer 26 is applied onto the electrode set-up in that a solution containing the polymer, a base or acid and other additives is deposited or imprinted and the solvent is removed. The polymer layer has a layer thickness of 10 to 100 μm, preferably between 20 and 40 μm. -
Electrodes circuit traces 22, 24, which are either formed also as cermet in one step together withelectrodes - The present invention is not limited to the exemplary embodiment described, but other specific embodiments in addition to the sensor described are conceivable as well.
- Thus, for example, an activated carbon layer can be provided on
polymer layer 26 to prevent the entry of gases that damagepolymer layer 26 such as nitrogen oxides or sulfur oxides. Furthermore, a temperature measuring unit may be additionally provided for compensating temperature influences on the measured potential differences.
Claims (16)
1. A sensor for determining a concentration of a gas in a gas mixture, comprising:
a measuring electrode, the measuring electrode being a pH sensitive electrode;
a reference electrode; and
a polymer layer in contact with the gas mixture and the measuring electrode.
2. The sensor according to claim 1 , wherein, in addition to measuring a pH value, a conductivity of the polymer layer is measured as well.
3. The sensor according to claim 1 , wherein the measuring electrode contains an iridium oxide.
4. The sensor according to claim 1 , wherein the measuring electrode is at least substantially shielded from the gas mixture by the polymer layer.
5. The sensor according to claim 1 , wherein at least one of the measuring electrode and the reference electrode is an interdigital electrode.
6. The sensor according to claim 1 , wherein the polymer layer includes a base.
7. The sensor according to claim 6 , wherein the polymer layer contains a quaternary ammonium compound as the base.
8. The sensor according to claim 1 , wherein the polymer layer contains an acid.
9. The sensor according to claim 8 , wherein the polymer layer contains a sulphonic acid as the acid.
10. The sensor according to claim 1 , wherein the polymer layer contains ethylcellulose.
11. The sensor according to claim 1 , wherein the sensor is a sensitive element in a fire detector.
12. The sensor according to claim 1 , wherein the sensor is a sensitive element in an air-quality sensor.
13. The sensor according to claim 1 , wherein the sensor is a sensitive element for detecting ammonia.
14. A method for manufacturing a sensor for determining a concentration of a gas in a gas mixture having at least two electrodes that are deposited on a ceramic substrate and a polymer layer, the method comprising:
in a first step, producing the electrodes on the ceramic substrate by depositing an electrode paste and a subsequent heat treatment; and
in a second step, depositing the polymer layer by applying a polymer solution on at least one of the ceramic substrate and the electrodes and subsequently removing a solvent.
15. The method according to claim 14 , wherein the polymer layer has a thickness of 10 to 50 μm.
16. The method according to claim 14 , further comprising:
in a third step, contacting the electrodes by a hardenable, precious metal-containing polymer.
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US12/418,150 US8758585B2 (en) | 2003-12-05 | 2009-04-03 | Sensor for determining gases and method for manufacturing the sensor |
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DE10356935A DE10356935A1 (en) | 2003-12-05 | 2003-12-05 | Sensor for the determination of gases and method for the production thereof |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20070080074A1 (en) * | 2005-10-07 | 2007-04-12 | Delphi Technologies, Inc. | Multicell ammonia sensor and method of use thereof |
WO2009103034A2 (en) * | 2008-02-13 | 2009-08-20 | Board Of Regents, The University Of Texas System | System, method and apparatus for an amorphous iridium oxide film ph sensor |
Families Citing this family (1)
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TWI565944B (en) * | 2015-12-11 | 2017-01-11 | 台灣奈米碳素股份有限公司 | A gas sensor and manufacture method thereof |
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US6241873B1 (en) * | 1997-02-20 | 2001-06-05 | Tdk Corporation | Sold electrolytes, carbon dioxide sensors and method for correcting the output of sensors |
US20040026267A1 (en) * | 2002-02-28 | 2004-02-12 | Thomas Brinz | Sensor for determining gases and method of manufacturing same |
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US5322602A (en) * | 1993-01-28 | 1994-06-21 | Teledyne Industries, Inc. | Gas sensors |
US5573648A (en) * | 1995-01-31 | 1996-11-12 | Atwood Systems And Controls | Gas sensor based on protonic conductive membranes |
US5841021A (en) * | 1995-09-05 | 1998-11-24 | De Castro; Emory S. | Solid state gas sensor and filter assembly |
US5716506A (en) * | 1995-10-06 | 1998-02-10 | Board Of Trustees Of The University Of Illinois | Electrochemical sensors for gas detection |
US6682638B1 (en) * | 1999-11-19 | 2004-01-27 | Perkin Elmer Llc | Film type solid polymer ionomer sensor and sensor cell |
-
2003
- 2003-12-05 DE DE10356935A patent/DE10356935A1/en not_active Ceased
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2004
- 2004-11-30 US US11/000,387 patent/US20050158457A1/en not_active Abandoned
-
2009
- 2009-04-03 US US12/418,150 patent/US8758585B2/en not_active Expired - Fee Related
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US4272328A (en) * | 1979-12-05 | 1981-06-09 | Eastman Kodak Company | Buffer overcoat for CO2 ion-selective electrodes |
US4900405A (en) * | 1987-07-15 | 1990-02-13 | Sri International | Surface type microelectronic gas and vapor sensor |
US5252292A (en) * | 1989-05-18 | 1993-10-12 | Mitsutoshi Hirata | Ammonia sensor |
US5720862A (en) * | 1995-04-07 | 1998-02-24 | Kyoto Daiichi Kagaku Co., Ltd. | Sensor and production method of and measurement method using the same |
US5958791A (en) * | 1996-09-27 | 1999-09-28 | Innovative Biotechnologies, Inc. | Interdigitated electrode arrays for liposome-enhanced immunoassay and test device |
US6241873B1 (en) * | 1997-02-20 | 2001-06-05 | Tdk Corporation | Sold electrolytes, carbon dioxide sensors and method for correcting the output of sensors |
US20040026267A1 (en) * | 2002-02-28 | 2004-02-12 | Thomas Brinz | Sensor for determining gases and method of manufacturing same |
Cited By (3)
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US20070080074A1 (en) * | 2005-10-07 | 2007-04-12 | Delphi Technologies, Inc. | Multicell ammonia sensor and method of use thereof |
WO2009103034A2 (en) * | 2008-02-13 | 2009-08-20 | Board Of Regents, The University Of Texas System | System, method and apparatus for an amorphous iridium oxide film ph sensor |
WO2009103034A3 (en) * | 2008-02-13 | 2009-10-08 | Board Of Regents, The University Of Texas System | System, method and apparatus for an amorphous iridium oxide film ph sensor |
Also Published As
Publication number | Publication date |
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US20090205958A1 (en) | 2009-08-20 |
DE10356935A1 (en) | 2005-06-30 |
US8758585B2 (en) | 2014-06-24 |
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