EP0059557A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method and apparatus for measuring the concentration of gases
Assignee: Capital Controls Co Inc
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Filing: 1982-02-17
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Granted: —
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Expires: 2002-02-17
Abstract
Abstract A gas sensing apparatus detects the presence of a gas such as chlorine in air, in very small quantities, and provides a rapid alarm. The apparatus incorporates a gas sensing composition which changes its electrical resistance more dramatically than previously possible in response to the presence of the gas, and electronic circuitry to sense and evaluate the patterns of resistance change during the first approximately 30 seconds after exposure to the gas and to estimate accurately gas concentration based on such initial resistance variations. Overall change in sensor resistance may detect gradually increasing gas levels. The sensor of the invention includes a metal and a metal oxide formed in combination with an inert support material into a porous mass of which the metal constitutes 50 to 95% by weight. The sensor structure (10) has a substrate (12) and comprises a sensor element (26) including a strip deposited between a pair of conductive pads (22,24) mounted over but insulated by a dielectric layer (20) from a relatively large heating resistor (18). The sensor is formed by and subsequently operated by the heating action of the resistor (18) and conductive pads (14, 16).
Inventors
- 👤 Matthew Zuckerman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 09:37
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
62 words
1 . A gas sensor which is adapted to change electrical resistance in response to the presence of a gas including a metal and an oxide of said metal characterized by the formation of said metal and metal oxide in combination with an inert support material into a porous mass wherein said metal constitutes between 50-95 weight percent of said porous mass.
Claim 2
Dependent Claim
62 words
1 . A gas sensor which is adapted to change electrical resistance in response to the presence of a gas including a metal and an oxide of said metal characterized by the formation of said metal and metal oxide in combination with an inert support material into a porous mass wherein said metal constitutes between 50-95 weight percent of said porous mass.
Claim 3
Dependent Claim
28 words
A gas sensor in accordance with claim 1 characterized by the selection of said metal from the group consisting of tin, titanium, iron, tantalum, zirconium, paladium and tungsten.
Claim 4
Dependent Claim
49 words
A gas sensor in accordance with claim 1 characterized by the inclusion in said porous mass of a compound of said metal and said gas so that said sensor composition is poised by a reverse concentration driving force to resist chemical reaction between said composition and the object gas.
Claim 5
Dependent Claim
26 words
A gas sensor in accordance with claim 1 characterized by the mounting of said sensor in a physical configuration which provides heat to said sensor material.
Claim 6
Dependent Claim
46 words
A gas sensor in accordance with claim 4 characterized by the maintenance of a heat level adapted to provide sufficient activation energy for the sorption of said gas on said material but insufficient activation energy to encourage the chemical reaction of said gas with said material.
Claim 7
Dependent Claim
32 words
A gas sensor in accordance with claim 4 characterized by the addition of a heat sink which provides a reservoir of thermal energy for said sensor material during exposure to said gas.
Claim 8
Dependent Claim
51 words
A gas sensor which is adapted to change electrical resistance in response to the presence of chlorine gas characterized by the inclusion of tin, an oxide of tin and an inert support material, all formed into a porous mass, metallic tin constituting between 50 and 95 weight percent of said mass.
Claim 9
Dependent Claim
51 words
A gas sensor which is adapted to change electrical resistance in response to the presence of chlorine gas characterized by the inclusion of tin, an oxide of tin and an inert support material, all formed into a porous mass, metallic tin constituting between 50 and 95 weight percent of said mass.
Claim 10
Dependent Claim
35 words
A gas sensor which is adapted to change electrical resistance in response to the presence of chlorine gas comprising tin and an oxide of tin characterized by the inclusion in said sensor of stannic chloride.
Claim 11
Dependent Claim
35 words
A gas sensor which is adapted to change electrical resistance in response to the presence of chlorine gas comprising tin and an oxide of tin characterized by the inclusion in said sensor of stannic chloride.
Claim 12
Dependent Claim
27 words
A composition in accordance with claim 8 characterized by the inclusion in said mass of tin in the range of 50-95 weight percent of said sensor material.
Claim 13
Dependent Claim
26 words
A composition in accordance with claim 8 characterized by the addition of an inert support material and the formation of said composition into a porous mass.
Claim 14
Independent Claim
110 words
A method for manufacturing a gas sensor which is adapted to change electrical resistance in response to the presence of a selected gas characterized by the steps of forming a slurry comprising a finely divided metal, an oxide of said metal and a composition which, when heated, will form an inert support material; providing a pair of electrical contacts; depositing said slurry between said electrical contacts and heating said slurry through a temperature cycle to form a porous mass engaging said electrical contacts; monitoring the resistance of the material between said electrical contacts during said heating cycle and terminating said heating cycle at a predetermined portion of the resistance profile.
Claim 15
Independent Claim
110 words
A method for manufacturing a gas sensor which is adapted to change electrical resistance in response to the presence of a selected gas characterized by the steps of forming a slurry comprising a finely divided metal, an oxide of said metal and a composition which, when heated, will form an inert support material; providing a pair of electrical contacts; depositing said slurry between said electrical contacts and heating said slurry through a temperature cycle to form a porous mass engaging said electrical contacts; monitoring the resistance of the material between said electrical contacts during said heating cycle and terminating said heating cycle at a predetermined portion of the resistance profile.
Claim 16
Dependent Claim
23 words
A method in accordance with claim 11 characterized by the termination of said heating cycle before said composition reaches its minimum resistance level.
Claim 17
Dependent Claim
25 words
A method in accordance with claim 11 characterized by the heating of said material at an increasing temperature until a desired resistance level is achieved.
Claim 18
Independent Claim
63 words
A method for manufacturing a gas sensor which is adapted to change electrical resistance in response to the presence of chlorine gas characterized by the steps of forming a slurry containing finely divided elemental tin, stannous oxide, stannic chloride, and a material which, when heated, forms an inert support material and heating said slurry through a temperature cycle to form a porous mass.
Claim 19
Independent Claim
63 words
A method for manufacturing a gas sensor which is adapted to change electrical resistance in response to the presence of chlorine gas characterized by the steps of forming a slurry containing finely divided elemental tin, stannous oxide, stannic chloride, and a material which, when heated, forms an inert support material and heating said slurry through a temperature cycle to form a porous mass.
Claim 20
Dependent Claim
20 words
A method in accordance with claim 14 characterized by the use of aluminum nitrate as the support material forming constituent.
Claim 21
Dependent Claim
36 words
A method in accordance with claim 14 characterized by the further step of monitoring the resistance of said slurry during said heating cycle and terminating said heating cycle at a predetermined portion of the resistance profile.
Claim 22
Dependent Claim
71 words
A method in accordance with claim 15 characterized by the use of a proportion of dry materials in said slurry as follows: finely divided tin between 50 and 95 weight percent of said dry materials; stannous oxide between 5 and 20 weight`percent of said dry materials; stannic chloride between 2 and 15 weight percent of said dry materials; and aluminum nitrate between 5 and 20 weight percent of said dry materials.
Claim 23
Dependent Claim
101 words
A gas sensor including a heater resistor adapted to make electrical contact with a source of electrical power, characterized by a surface overlaying said heater resistor and in thermal communication therewith, said surface being electrically insulated from said heater resistor, a pair of conductive contacts associated with said surface and defining a gap on said surface between said contacts, and a gas responsive material which changes electrical resistance in response to the presence of gas deposited in said gap on said surface in electrical communication with said contacts, application of electrical power to said heater resistor heating said gas sensing material.
Claim 24
Dependent Claim
101 words
A gas sensor including a heater resistor adapted to make electrical contact with a source of electrical power, characterized by a surface overlaying said heater resistor and in thermal communication therewith, said surface being electrically insulated from said heater resistor, a pair of conductive contacts associated with said surface and defining a gap on said surface between said contacts, and a gas responsive material which changes electrical resistance in response to the presence of gas deposited in said gap on said surface in electrical communication with said contacts, application of electrical power to said heater resistor heating said gas sensing material.
Claim 25
Dependent Claim
30 words
A gas sensor in accordance with claim 18 characterized by the use of a heater resistor having an area which is large in comparison with the area of said gap.
Claim 26
Dependent Claim
18 words
Apparatus in accordance with claim 18 characterized by the width of said gap being less than 4 mils.
Claim 27
Dependent Claim
23 words
Apparatus in accordance with claim 18 characterized by the formation of said surface on an electrically nonconductive substrate deposited over said heating resistor.
Claim 28
Dependent Claim
25 words
Apparatus in accordance with claim 18 characterized by the addition of a heat sink for providing a reservoir of heat for said gas responsive material.
Claim 29
Independent Claim
139 words
A method for manufacturing a gas monitor including a heater resistor adapted to assume increased temperature in response to the application of electrical power and a surface in thermal communication with said heater resistor but electrically insulated from said heater resistor, said surface having electrical contacts defining a gap therebetween, characterized by the steps of depositing selected materials on said surface in said gap, said selected materials adapted, when heated, to form a body which changes resistance.in response to the presence of selected gas, heating said heater resistor during manufacture to relatively high temperatures adapted to form said selected materials into said body in electrical contact with said conductive pads, thereafter during operation, heating said heater resistor to relatively low temperatures adapted to remove moisture from said sensor and provide appropriate activation energy for the operation of said sensor.
Claim 30
Independent Claim
139 words
A method for manufacturing a gas monitor including a heater resistor adapted to assume increased temperature in response to the application of electrical power and a surface in thermal communication with said heater resistor but electrically insulated from said heater resistor, said surface having electrical contacts defining a gap therebetween, characterized by the steps of depositing selected materials on said surface in said gap, said selected materials adapted, when heated, to form a body which changes resistance.in response to the presence of selected gas, heating said heater resistor during manufacture to relatively high temperatures adapted to form said selected materials into said body in electrical contact with said conductive pads, thereafter during operation, heating said heater resistor to relatively low temperatures adapted to remove moisture from said sensor and provide appropriate activation energy for the operation of said sensor.
Claim 31
Dependent Claim
47 words
The method in accordance with claim 23 characterized by the formation of said heater resistor using a resistance film deposited on a substrate and the formation of said surface in thermal communication with said heater resistor by the depositing of a dielectric material over said resistance film.
Claim 32
Dependent Claim
65 words
A gas sensing material comprising a metal and an oxide of said metal, characterized by the presence in said composition of said metal in a range of 50-95 weight percent of said composition and further characterized by the existence of a reversible change in relative resistance in response to the presence of gas in excess of ten percent for each part per million gas present.
Claim 33
Dependent Claim
65 words
A gas sensing material comprising a metal and an oxide of said metal, characterized by the presence in said composition of said metal in a range of 50-95 weight percent of said composition and further characterized by the existence of a reversible change in relative resistance in response to the presence of gas in excess of ten percent for each part per million gas present.
Claim 34
Dependent Claim
85 words
Apparatus for detecting a selected gas comprising a sensor which is adapted to change electrical resistance in response to the presence of the selected gas and circuit means electrically-interconnected with said sensor for detecting change of the electrical resistance of said sensor and for providing an output indication of the presence of gas characterized by the detection of gas and the generation of said output indication in response to the rate of change of said resistance, rather than the magnitude of the change of resistance.
Claim 35
Dependent Claim
85 words
Apparatus for detecting a selected gas comprising a sensor which is adapted to change electrical resistance in response to the presence of the selected gas and circuit means electrically-interconnected with said sensor for detecting change of the electrical resistance of said sensor and for providing an output indication of the presence of gas characterized by the detection of gas and the generation of said output indication in response to the rate of change of said resistance, rather than the magnitude of the change of resistance.
Claim 36
Dependent Claim
54 words
2 7. Apparatus in accordance with claim 26 wherein said circuit means is characterized by means for generating a signal indicative of the rate of change of said sensor resistance, and means for maintaining a predetermined signal level and means for providing an output signal when said generated signal exceeds said predetermined signal level.
Claim 37
Dependent Claim
39 words
Apparatus in accordance with claim 26 characterized by said circuit means further including means for monitoring the level of resistance of said sensor and for ; providing an output indication when said level of resistance exceeds a predetermined level.
Claim 38
Dependent Claim
27 words
Apparatus in accordance with claim 26 characterized by the detection of the rate of change of resistance with a time constant in the range of 5-15 seconds.
References Cited (Backward Citations)
No citation records indexed.
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