GB2180653A - Electrochemical cell - Google Patents
Electrochemical cell Download PDFInfo
- Publication number
- GB2180653A GB2180653A GB08621325A GB8621325A GB2180653A GB 2180653 A GB2180653 A GB 2180653A GB 08621325 A GB08621325 A GB 08621325A GB 8621325 A GB8621325 A GB 8621325A GB 2180653 A GB2180653 A GB 2180653A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cell
- electrode
- electrolyte
- ofthe
- carrier
- 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.)
- Granted
Links
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 15
- 230000004888 barrier function Effects 0.000 claims abstract description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 4
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 3
- 239000010439 graphite Substances 0.000 claims abstract description 3
- 239000012051 hydrophobic carrier Substances 0.000 claims abstract description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims abstract description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 claims abstract description 3
- 239000005871 repellent Substances 0.000 claims abstract description 3
- -1 nitrate ions Chemical class 0.000 claims abstract 2
- 210000004027 cell Anatomy 0.000 claims description 31
- 239000003792 electrolyte Substances 0.000 claims description 23
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000011888 foil Substances 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 5
- 229920000642 polymer Polymers 0.000 claims description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 4
- 239000010457 zeolite Substances 0.000 claims description 4
- 229910021536 Zeolite Inorganic materials 0.000 claims description 3
- 210000005056 cell body Anatomy 0.000 claims description 3
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 3
- 239000011148 porous material Substances 0.000 claims description 3
- 230000035945 sensitivity Effects 0.000 claims description 3
- 239000002253 acid Substances 0.000 claims description 2
- 150000007513 acids Chemical class 0.000 claims description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 2
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 2
- 239000011230 binding agent Substances 0.000 claims description 2
- 239000011521 glass Substances 0.000 claims description 2
- 239000011159 matrix material Substances 0.000 claims description 2
- 239000000843 powder Substances 0.000 claims description 2
- POFWRMVFWIJXHP-UHFFFAOYSA-N n-benzyl-9-(oxan-2-yl)purin-6-amine Chemical compound C=1C=CC=CC=1CNC(C=1N=C2)=NC=NC=1N2C1CCCCO1 POFWRMVFWIJXHP-UHFFFAOYSA-N 0.000 claims 2
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 claims 1
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 claims 1
- 239000004033 plastic Substances 0.000 claims 1
- 229920003023 plastic Polymers 0.000 claims 1
- 229910002651 NO3 Inorganic materials 0.000 abstract 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 abstract 1
- 230000003647 oxidation Effects 0.000 abstract 1
- 238000007254 oxidation reaction Methods 0.000 abstract 1
- 238000006243 chemical reaction Methods 0.000 description 12
- 238000005259 measurement Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 238000006722 reduction reaction Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 230000002209 hydrophobic effect Effects 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000001376 precipitating effect Effects 0.000 description 2
- 229920002994 synthetic fiber Polymers 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000012876 carrier material Substances 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000007323 disproportionation reaction Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
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
- G01N27/4045—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 for gases other than oxygen
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Immunology (AREA)
- Engineering & Computer Science (AREA)
- Pathology (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Electrochemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Molecular Biology (AREA)
- Combustion & Propulsion (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Measuring Oxygen Concentration In Cells (AREA)
- Inert Electrodes (AREA)
- Hybrid Cells (AREA)
Abstract
An electrochemical three-electrode cell for measuring of nitrogen oxides comprises a space 1 for a working electrode space 4 separated by a proton-conducting barrier element 3 from a space 2 of a counter-electrode 7 and a reference electrode 8. The working electrode 4 comprises a porous, hydrophobic carrier 5 carrying a catalyser 6 for oxidation to nitrate which has been made water-repellent, e.g. carbon or graphite in PTFE. The barrier prevents reduction of nitrate ions at the counterelectrode. <IMAGE>
Description
SPECIFICATION
Electrochemical cell
The present invention relates to an electrochemical cell, especiallyforthe measurement of nitric oxides.
Since appreciable environmental pollution emanates from nitric oxides, the exact determination of nitric oxide components in exhaust gases, and also in reaction gases, is necessaryforthe effective control of countermeasures. These countermeasures are, for example, catalytic reduction with exclusion of oxygen to nitrogen or reduction with ammonia to nitrogen and water in case of oxygen components in the exhaust gases.
An electrochemical three-electrode cell for measuring nitric oxide components in a gas is known from
DE-OS 25 264. This cell has the disadvantage that disproportionations in the electrolyte occur in the case of high nitric oxide content or over longer periods of operation of the cell. Back reactions occur at the counter- electrode and after a certain time simulate higher nitric oxide concentrations.
It would thus be desirableto prevent back reactions ofthe end products after conversion at the working electrode and also avoid pre-reactions of nitric oxides with water or with still present oxygen components in the combustion or reaction gas.
According to the present invention there is provided an electrochemical cell comprising a cell body, a working electrode disposed in a first space in the body to be in contact with an electrolyte therein, a counter-electrode and a reference electrode disposed in a second space in the body to be in contact with the electrolyte, and a proton-conductive barrier element separating the first and second spaces from each other, the first electrode comprising a porous hydrophobic carrier and a water-repellent catalyser on a side ofthe carrierfacing the electrolyte.
A cell embodying the present invention may have the advantage that the reaction products do not reach the counter-electrode and thus cannot influence the third electrode so that no potential changes falsifying the measurement value are avoided. Through the formation of the working electrode as a two-layer electrode from hydrophobic material, it is ensured that NO2 is not included in the measurement to an intolerably large degree through pre-reaction with condensed water as well as oxygen. Such advantages are due to the mode of operation ofthe cell. The gas to be measured washes the porous carrier of the working electrode and passes through this and the catalyser until it comes into contactwith the electrolyte.Due to the hydrophobic formation of the working electrode, the wetting of this electrode by precipitating watervapour is prevented.
Consequently, the NO2, which readily reacts with water, cannot combine through a pre-reaction with the precipitated water to become NO30, which would lead to the NO2 being only partially detected by the measurement.
Atthe boundary layer between the catalyser of the working electrode and the electrolyte, thefollowing reactions significantforthe measurement take place: NO+2H20 < NO3()+4Hf3+3e(3, NO2+ H2ONO3O+2HO+e.
The hydrated protons diffusethrough the barrier element to the counter-electrode, at which they combine with the oxygen which gets through the carrier material and the material ofthe counter-electrodeto the boundary layer between the counter-electrode and the electrolyte: 4H0++O2+4e2H2O.
The current generated by these reactions is a measure of the concentration of NOx.
The reference electrode serves to keep the potential setting constant at the working electrode.
The barrier element serves to prevent NO30- reaching the counter-electrode and falsifying the measurement result due to the reaction NO36+2H03+e8 < NO2+H20 and further reduction reactions of N030 or NO2.
In this manner, pre-reactions and reduction reactions are prevented by the barrier element and theformation ofthe working electrode. Due to the fact that only the desired reactions take place, the cell is accurate and stable in the long term and is usable for measurement of low concentrations (C < 100 parts per million) aswell as high nitric oxide proportions (C > 1000 parts per million).
The carrier of the working electrode, and a carrier of the counter-electrode and the reference electrode, preferably have capillary passages of such a diameterthatthe capillary openings cannot become clogged by water vapour condensation. This measure enhances the NO2 sensitivity ofthe cell even in the case ofhigh water vapour content of the gas.
The electrolyte can be fixed to a polymer matrix, for example acids held in zeolites, glass powder or other porous materials, and this offers the advantage that there is no dilution, which reaches beyond the edge zones, ofthe electrolyte through precipitating water vapour. Thus, conductivity fluctuations of the electrolyte can be prevented and the sensitivity of the system is stabilised.
Preferably, the working electrode comprises a carbon catalyser layer, which iswater-repellentand comprises a 10 to 100 millimetres thick, oxidation-stable hard carbon, synthetic graphite or graphite with 40 to 80 percentbyweightofpolytetrafluoroethylene binder.
In that case, an optimum measure of hydrophobicity and thereby of diffusion current linearity ofthe electrode may be achieved if the PTFE proportion is so set that the sensitivityfactor NO2/NO rises from 1 to 1/9.
Preferably, the barrier element is a sulfonated polymer foil inserted into the cell body.
Embodiments ofthe present invention will now be more particularly described by way of example with reference to the accompanying drawings, in which:
Figure 1 is an exploded perspective view of a first cell embodying the invention;
Figure2 is a horizontal sectional view of the cell of Figure 1; and
Figure 3 is a horizontal sectional view of a second cell embodying the invention.
Referring now to the drawings, there is shown in Figures 1 and 2 an electrochemical cell having a body which is formed from two synthetic material blocks 11 a and 11 b with a bore for the reception of electrolyte 10. The two blocks 11 a and 11 bare secured together by screws and a barrier element 3 is clamped between them. The bore is closed off outwardly by two carriers 5 and 9. The carrier Son the side facing the electrolyte 10 carries carbon catalyser layer 6 of a working electrode 4. The other carrier 9 on its side facing the electrolyte 10 carries a counter-electrode 7 and a reference electrode 8.
The electrodes 6,7 and 8 can, according to the process described in DE-P 33 24 682, be welded to terminals 12, 13 and 14 in liquid-tight mannerthrough the carriers 5 and 9. A channel 18 servesforfilling-in ofthe electrolyte.
Figure 3 shows a miniature cell in which a foil 15, consisting of sulfonated polymers or of phosphoric acid, held in zeolite, rests directly against the working electrode 4 on one side and against the counter-electrode7 and reference electrode 8 on the other side. Thisfoil 15 takes over the function of the barrier element as weil as that ofthe electrolyte. It can be glued into a groove 17 of a synthetic material body 16 by partially dissolving the walls ofthe groove 17 by a solvent and then pushing in the foil 15, which is matched in size to the groove.
Claims (18)
1. An electrochemical cell comprising a cell body, a working electrode disposed in a first space in the body to be in contact with an electrolyte therein, a counter-electrode and a reference electrode disposed in a second space in the body to be in contact with the electrolyte, and a proton-conductive barrier element separating the first and second spaces from each other, the first electrode comprising a porous hydrophobic carrier and a water-repellent catalyser on a side of the carrier facing the electrolyte.
2. Acell as claimed in claim 1,wherein the porosity of the carrier is provided by capillary bores of such a diameter as to resist clogging by water vapour condensate.
3. A cell as claimed in either claim 1 or claim 2, wherein the electrolyte is captive.
4. A cell as claimed in claim 3, wherein the electrolyte is captive in a polymer matrix.
5. A cell as claimed in claim 4, wherein the electrolyte comprises acids held in a porous material.
6. A cell as claimed in claim 5, wherein the porous material comprises zeolite or glass powder.
7. A cell as claimed in any one of the preceding claims, wherein the catalyser comprises a layer of oxidation-stable material with 40 to 80 percent by weight of polytetrafluoroethylene binder, the layer being 10 to 100 millimetres thick.
8. A cell as claimed in claim 7, wherein the oxidation-stable material is one of carbon, graphite and synthetic graphite.
9. A cell as claimed in either claim 7 or claim 8, wherein the hydrophobicity of the catalyser is so increased by setting ofthe binderthatthe sensitivity factor of nitrogen dioxide/nitric oxide rises from 1/3 to 1/9.
10. A cell as claimed in any one of the preceding claims, wherein the barrier element is a sulfonated polymerfoil.
11. A cell as claimed in any one of the preceding claims, wherein the body comprises two members which are connected togetherwith the barrier element arranged therebetween and which define a bore receiving the electrolyte, the bore being closed at one end thereof by the carrier ofthe first electrode and at the other end thereof by a carrier ofthe counter-electrode and the reference electrode.
12. A cell as claimed in either claim 1 or claim 2, wherein the barrier element comprises a foil in which the electrolyte is integrated and which at one side contacts the working electrode and at the other side contacts the counter-electrode and the reference electrode.
13. A cell as claimed in claim 12, wherein the foil comprises sulfonated polymers.
14. A cell as claimed in claim 12, wherein the foil comprises phosphoric acid held in zeolite.
15. Acell as claimed in any one of claims 12 to 14, wherein thefoil is glued in a groove in the body.
16. A cell as claimed in any one of the preceding claims, wherein the body is made of plastics material.
17. An electrochemical cell substantially as herein before described with reference to Figures 1 and 2 ofthe accompanying drawings.
18. An electrochemical cell substantially as hereinbefore described with reference to Figure 3 ofthe accompanying drawings.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19853532674 DE3532674A1 (en) | 1985-09-13 | 1985-09-13 | ELECTROCHEMICAL THREE-ELECTRODE CELL FOR MEASURING NITROGEN OXIDES |
Publications (3)
Publication Number | Publication Date |
---|---|
GB8621325D0 GB8621325D0 (en) | 1986-10-15 |
GB2180653A true GB2180653A (en) | 1987-04-01 |
GB2180653B GB2180653B (en) | 1990-02-07 |
Family
ID=6280851
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB8621325A Expired - Fee Related GB2180653B (en) | 1985-09-13 | 1986-09-04 | Electrochemical cell |
Country Status (2)
Country | Link |
---|---|
DE (1) | DE3532674A1 (en) |
GB (1) | GB2180653B (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2267348A (en) * | 1992-05-26 | 1993-12-01 | Walter John King | Electrochemical oxygen sensor |
EP0637379A1 (en) * | 1992-04-21 | 1995-02-08 | MALINSKI, Tadeusz | Nitric oxide sensor |
US5603820A (en) * | 1992-04-21 | 1997-02-18 | The United States Of America As Represented By The Department Of Health And Human Services | Nitric oxide sensor |
WO2001014864A2 (en) * | 1999-08-24 | 2001-03-01 | Central Research Laboratories Ltd. | A gas sensor and its method of manufacture |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4132178A1 (en) * | 1991-07-26 | 1993-01-28 | Hl Planartechnik Gmbh | Electrochemical sensor, esp. for oxygen@ measurement - has reference electrode in separate part of electrolyte chamber, with layer preventing ion transmission |
DE4125099C2 (en) * | 1991-07-30 | 1995-02-23 | Daimler Benz Ag | Method and device for measuring ammonia in air and exhaust gases containing NO¶x¶ |
DE4316970C1 (en) * | 1993-05-21 | 1994-08-25 | Daimler Benz Ag | Method for determining ammonia in gases |
DE19803805B4 (en) * | 1998-01-31 | 2015-10-29 | Volkswagen Ag | NOx sensor |
DE19859198C2 (en) * | 1998-12-21 | 2003-12-18 | Envitec Wismar Gmbh | Electrochemical gas sensor with high selectivity for nitrogen monoxide |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4025412A (en) * | 1975-12-04 | 1977-05-24 | General Electric Company | Electrically biased two electrode, electrochemical gas sensor with a H.sub.2 |
US4265714A (en) * | 1980-03-24 | 1981-05-05 | General Electric Company | Gas sensing and measuring device and process using catalytic graphite sensing electrode |
GB1597413A (en) * | 1977-02-28 | 1981-09-09 | Gen Electric | Gas sensors |
GB2094005A (en) * | 1981-02-03 | 1982-09-08 | Coal Industry Patents Ltd | Electrochemical gas sensor |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3776832A (en) * | 1970-11-10 | 1973-12-04 | Energetics Science | Electrochemical detection cell |
US4001103A (en) * | 1974-05-07 | 1977-01-04 | Energetics Science, Inc. | Device for the detection and measurement of NO and NO2 gases |
DE2655318C3 (en) * | 1976-12-07 | 1979-11-29 | Draegerwerk Ag, 2400 Luebeck | Polarographic measuring probe with diffusion film membrane |
-
1985
- 1985-09-13 DE DE19853532674 patent/DE3532674A1/en active Granted
-
1986
- 1986-09-04 GB GB8621325A patent/GB2180653B/en not_active Expired - Fee Related
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4025412A (en) * | 1975-12-04 | 1977-05-24 | General Electric Company | Electrically biased two electrode, electrochemical gas sensor with a H.sub.2 |
GB1597413A (en) * | 1977-02-28 | 1981-09-09 | Gen Electric | Gas sensors |
US4265714A (en) * | 1980-03-24 | 1981-05-05 | General Electric Company | Gas sensing and measuring device and process using catalytic graphite sensing electrode |
GB2094005A (en) * | 1981-02-03 | 1982-09-08 | Coal Industry Patents Ltd | Electrochemical gas sensor |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0637379A1 (en) * | 1992-04-21 | 1995-02-08 | MALINSKI, Tadeusz | Nitric oxide sensor |
EP0637379A4 (en) * | 1992-04-21 | 1996-05-08 | Tadeusz Malinski | Nitric oxide sensor. |
US5603820A (en) * | 1992-04-21 | 1997-02-18 | The United States Of America As Represented By The Department Of Health And Human Services | Nitric oxide sensor |
GB2267348A (en) * | 1992-05-26 | 1993-12-01 | Walter John King | Electrochemical oxygen sensor |
WO2001014864A2 (en) * | 1999-08-24 | 2001-03-01 | Central Research Laboratories Ltd. | A gas sensor and its method of manufacture |
WO2001014864A3 (en) * | 1999-08-24 | 2001-05-31 | Central Research Lab Ltd | A gas sensor and its method of manufacture |
Also Published As
Publication number | Publication date |
---|---|
DE3532674C2 (en) | 1988-01-21 |
GB8621325D0 (en) | 1986-10-15 |
GB2180653B (en) | 1990-02-07 |
DE3532674A1 (en) | 1987-03-26 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19960904 |