US5397442A
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US
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Sensor and method for accurately measuring concentrations of oxide compounds in gas mixtures
Assignee: Gas Technology Institute
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Filing: 1994-03-09
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Granted: 1995-03-14
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Expires: 2014-03-09
Abstract
Abstract Sensors (10, 40) accurately measure the concentration of an oxide compound, such as nitrogen oxide NO x , in a gas mixture (11) which can include oxygen O 2 . The sensors (10, 40) each comprise a chamber (12, 42) adapted to receive the gas mixture (11) as well as first and second electrochemical cells (16, 17) for consuming oxygen and/or the oxide compound in the chamber (12, 42). The first electrochemical cell (16) comprises a first internal electrode (16a) inside the chamber (12, 42), a first external electrode (16b) outside the chamber (12, 42), and a first electrolyte body (14') therebetween. The second electrochemical cell (17) comprises a second internal electrode (17a) inside the chamber (12, 42), a second external electrode (17b) outside the chamber (12, 42), and a second electrolyte body (14") therebetween. The first and second electrolyte bodies (14', 14") are permeable to oxygen ions. Significantly, the first and second internal electrodes (16a, 17a) are metal oxides having a perovskite lattice structure, which generally exhibit high relative selectivity between oxide compounds, including NO x , and O 2 . The electrical characteristics of the first and second electrochemical cells (16, 17) are manipulated and/or monitored in order to determine the concentration of NO x within the chambers (12, 42) and the gas mixture (11).
Inventors
- 👤 Eric D. Wachsman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:22
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/403; G01N27/406; G01N27/407; G01N27/4073; G01N27/4074; G01N33/00; G01N33/0004; G01N33/0009; G01N33/0027; G01N33/0031; G01N33/0036; G01N33/0037; Y; Y02; Y02A; Y02A50/00; Y02A50/20
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
190 words
A sensor for accurately measuring a concentration of an oxide compound in a gas mixture, comprising: a chamber adapted to receive the gas mixture; a first cell means comprising a first internal electrode inside said chamber, a first external electrode outside said chamber, and a first electrolyte body therebetween, said first electrolyte body is substantially permeable to oxygen ions when said first electrolyte body is electrically biased during operation of the sensor, said first internal electrode comprising a perovskite having selectivity to reduce oxygen and, not the oxide compound, in said chamber; and a second cell means comprising a second internal electrode inside said chamber, a second external electrode outside said chamber, and a second electrolyte body therebetween, said second electrolyte body is substantially permeable to said oxygen ions when said second electrolyte body is electrically biased during operation of the sensor, said second internal electrode comprising a metal oxide having selectivity to reduce the oxide compound in said chamber after depletion of the oxygen within said chamber; whereby an electrical characteristic associated with said second cell means corresponds to the concentration of the oxide compound in the gas mixture.
Claim 2
Dependent Claim
190 words
A sensor for accurately measuring a concentration of an oxide compound in a gas mixture, comprising: a chamber adapted to receive the gas mixture; a first cell means comprising a first internal electrode inside said chamber, a first external electrode outside said chamber, and a first electrolyte body therebetween, said first electrolyte body is substantially permeable to oxygen ions when said first electrolyte body is electrically biased during operation of the sensor, said first internal electrode comprising a perovskite having selectivity to reduce oxygen and, not the oxide compound, in said chamber; and a second cell means comprising a second internal electrode inside said chamber, a second external electrode outside said chamber, and a second electrolyte body therebetween, said second electrolyte body is substantially permeable to said oxygen ions when said second electrolyte body is electrically biased during operation of the sensor, said second internal electrode comprising a metal oxide having selectivity to reduce the oxide compound in said chamber after depletion of the oxygen within said chamber; whereby an electrical characteristic associated with said second cell means corresponds to the concentration of the oxide compound in the gas mixture.
Claim 3
Dependent Claim
34 words
The sensor of claim 1, wherein said chamber comprises an enclosure for housing said internal electrodes and an elongated aperture in the shape of a pin through which the gas mixture enters said enclosure.
Claim 4
Dependent Claim
73 words
The sensor of claim 1, wherein said chamber comprises an elongated enclosure in the shape of a tube for housing said internal electrodes, said enclosure having first and second apertures for receiving and expelling the gas mixture respectively, said first and second internal electrodes disposed in succession along an axis connecting said first and second apertures, said first internal electrode disposed along said axis between said first aperture and said second internal electrode.
Claim 5
Dependent Claim
13 words
The sensor of claim 1, wherein said second internal electrode comprises a perovskite.
Claim 6
Dependent Claim
21 words
The sensor of claim 4, wherein said perovskite is selected from the group consisting of LaRuO 3 and LaMnO 3 .
Claim 7
Dependent Claim
21 words
The sensor of claim 1, wherein said first and second electrolyte bodies are portions of a singular wall of said chamber.
Claim 8
Dependent Claim
14 words
The sensor of claim 1, wherein said first and second electrolyte bodies comprise zirconia.
Claim 9
Dependent Claim
36 words
The sensor of claim 1, wherein said perovskite is selected from the group consisting of La 2 CuO 4 , LaNiO 3 , LaFeO 3 , LaCoO 3 , LaMnO 3 , and LaSrCoO 3 .
Claim 10
Dependent Claim
196 words
A sensor for accurately measuring a concentration of an oxide compound in a gas mixture, comprising: a chamber adapted to receive the gas mixture; a first cell means comprising a first internal electrode inside said chamber, a first external electrode outside said chamber, and a first electrolyte body therebetween, said first electrolyte body is substantially permeable to oxygen ions when said first electrolyte body is electrically biased during operation of the sensor, said first internal electrode comprising a perovskite having selectivity to reduce the oxygen and, not the oxide compound; and a second cell means comprising a second internal electrode inside said chamber, a second external electrode outside said chamber, and a second electrolyte body therebetween, said second electrolyte body is permeable to said oxygen ions when said second electrolyte body is electrically biased during operation of the sensor, said second internal electrode comprising a material having selectivity to concurrently reduce both the oxygen and the oxide compound; whereby first and second electrical characteristics associated with said first and second cell means are measured and the concentration of the oxide compound in the gas mixture is determined by mathematically combining said first and second electrical characteristics.
Claim 11
Dependent Claim
196 words
A sensor for accurately measuring a concentration of an oxide compound in a gas mixture, comprising: a chamber adapted to receive the gas mixture; a first cell means comprising a first internal electrode inside said chamber, a first external electrode outside said chamber, and a first electrolyte body therebetween, said first electrolyte body is substantially permeable to oxygen ions when said first electrolyte body is electrically biased during operation of the sensor, said first internal electrode comprising a perovskite having selectivity to reduce the oxygen and, not the oxide compound; and a second cell means comprising a second internal electrode inside said chamber, a second external electrode outside said chamber, and a second electrolyte body therebetween, said second electrolyte body is permeable to said oxygen ions when said second electrolyte body is electrically biased during operation of the sensor, said second internal electrode comprising a material having selectivity to concurrently reduce both the oxygen and the oxide compound; whereby first and second electrical characteristics associated with said first and second cell means are measured and the concentration of the oxide compound in the gas mixture is determined by mathematically combining said first and second electrical characteristics.
Claim 12
Dependent Claim
34 words
The sensor of claim 9, wherein said chamber comprises an enclosure for housing said internal electrodes and an elongated aperture in the shape of a pin through which the gas mixture enters said enclosure.
Claim 13
Dependent Claim
73 words
The sensor of claim 9, wherein said chamber comprises an elongated enclosure in the shape of a tube for housing said internal electrodes, said enclosure having first and second apertures for receiving and expelling the gas mixture respectively, said first and second internal electrodes disposed in succession along an axis connecting said first and second apertures, said first internal electrode disposed along said axis between said first aperture and said second internal electrode.
Claim 14
Dependent Claim
13 words
The sensor of claim 9, wherein said second internal electrode is a perovskite.
Claim 15
Dependent Claim
21 words
The sensor of claim 12, wherein said perovskite is selected from the group consisting of LaRuO 3 and LaMnO 3 .
Claim 16
Dependent Claim
21 words
The sensor of claim 9, wherein said first and second electrolyte bodies are portions of a singular wall of said chamber.
Claim 17
Dependent Claim
14 words
The sensor of claim 9, wherein said first and second electrolyte bodies comprise zirconia.
Claim 18
Dependent Claim
36 words
The sensor of claim 9, wherein said perovskite is selected from the group consisting of La 2 CuO 4 , LaNiO 3 , LaFeO 3 , LaCoO 3 , LaMnO 3 , and LaSrCoO 3 .
Claim 19
Dependent Claim
20 words
The sensor of claim 9, wherein said second internal electrode is selected from the group consisting of Pt and Rh.
Claim 20
Dependent Claim
25 words
The sensor of claim 9, wherein said second internal electrode comprises a perovskite selected from the group consisting of LaRuO 3 and LaMnO 3 .
Claim 21
Independent Claim
98 words
A method for accurately measuring a concentration of an oxide compound in a gas mixture, comprising the steps of: exposing the gas mixture to a first internal electrode comprising a perovskite and a second internal electrode comprising a metal oxide; selectively reducing the oxygen with said first internal electrode without substantially depleting the oxide compound in the gas mixture; reducing the oxide compound with said second internal electrode after said first internal electrode depletes the oxygen; and measuring electrical characteristic associated with said second internal electrode to determine the concentration of the oxide compound in the gas mixture.
Claim 22
Independent Claim
98 words
A method for accurately measuring a concentration of an oxide compound in a gas mixture, comprising the steps of: exposing the gas mixture to a first internal electrode comprising a perovskite and a second internal electrode comprising a metal oxide; selectively reducing the oxygen with said first internal electrode without substantially depleting the oxide compound in the gas mixture; reducing the oxide compound with said second internal electrode after said first internal electrode depletes the oxygen; and measuring electrical characteristic associated with said second internal electrode to determine the concentration of the oxide compound in the gas mixture.
Claim 23
Dependent Claim
38 words
The method of claim 19, further comprising the steps of: measuring the electrical current between said first internal electrode and a first external electrode; measuring the electrical current between said second internal electrode and a second external electrode.
Claim 24
Dependent Claim
36 words
The method of claim 19, further comprising the steps of: measuring the voltage between said first internal electrode and a first external electrode; measuring the voltage between said second internal electrode and a second external electrode.
Claim 25
Dependent Claim
13 words
The method of claim 19, wherein the oxide compound is NO x .
Claim 26
Independent Claim
105 words
A method for accurately measuring a concentration of an oxide compound in a gas mixture, comprising the steps of: exposing the gas mixture to first internal and second internal electrodes, said first electrode comprising a perovskite; selectively reducing the oxygen with said first internal electrode without substantially depleting the oxide compound in the gas mixture; reducing both the oxygen and the oxide compound with said second internal electrode; measuring first and second electrical characteristics associated with said first internal and second internal electrodes respectively; and determining the concentration of the oxide compound in the gas mixture by mathematically combining said first and second electrical characteristics.
Claim 27
Independent Claim
105 words
A method for accurately measuring a concentration of an oxide compound in a gas mixture, comprising the steps of: exposing the gas mixture to first internal and second internal electrodes, said first electrode comprising a perovskite; selectively reducing the oxygen with said first internal electrode without substantially depleting the oxide compound in the gas mixture; reducing both the oxygen and the oxide compound with said second internal electrode; measuring first and second electrical characteristics associated with said first internal and second internal electrodes respectively; and determining the concentration of the oxide compound in the gas mixture by mathematically combining said first and second electrical characteristics.
Claim 28
Dependent Claim
38 words
The method of claim 23, further comprising the steps of: measuring the electrical current between said first internal electrode and a first external electrode; measuring the electrical current between said second internal electrode and a second external electrode.
Claim 29
Dependent Claim
36 words
The method of claim 23, further comprising the steps of: measuring the voltage between said first internal electrode and a first external electrode; measuring the voltage between said second internal electrode and a second external electrode.
Claim 30
Dependent Claim
13 words
The method of claim 23, wherein the oxide compound is NO x .
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-03-13 | 1998-09-12 | 1999-03-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-03-13 | 2002-09-12 | 2003-03-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-03-13 | 2006-09-12 | 2007-03-14 | $7700.00 | Window Closed / Lapsed |