US4761710A
Expired / Lapsed
US
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Polyimide capacitive humidity sensing element
Assignee: Industrial Technology Research Institute
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Filing: 1987-06-23
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Granted: 1988-08-02
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Expires: 2007-06-23
Abstract
Abstract The present invention relates to a humidity sensing element having a polyimide moisture sensing film. It is of a capacitive structure containing, without the use of adhesives, a polyimide film which is either sandwiched between a corrosion resisting metal substrate and a thin moisture permeable gold layer, or vapor deposited on both sides thereof with a moisture permeable thin gold layer.
Inventors
- 👤 Stephen G. L. Chen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 23:39
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/125; G01N27/126; C; C08; C08G; C08G73/00; C08G73/06; C08G73/10; C08G73/1067; G01N27/22; G01N27/223; G01N27/225
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
84 words
A capacitive humidity sensing element comprising: a corrosion resistant metal substrate; a humidity sensitive polyimide film coated on the corrosion resistant metal substrate; and a moisture permeable thin gold electrode on top of the humidity sensitive polyimide film, the humidity sensitive polyimide film being produced by reacting: a dianhydride selected from the group consisting of pyromellitic dianhydride and 3,3'-4,4'-benzophenon tetracarboxylic acid dianhydride, with a diamine selected from the group consisting of p-phenylene diamine, m-phenylene diamine, 4,4'-diamino-diphenyl methane, 4,4'-diamino-diphenyl ether, 3,4'-diamino-diphenyl ether and 4,4'-diamino-diphenyl sulfide.
Claim 2
Dependent Claim
84 words
A capacitive humidity sensing element comprising: a corrosion resistant metal substrate; a humidity sensitive polyimide film coated on the corrosion resistant metal substrate; and a moisture permeable thin gold electrode on top of the humidity sensitive polyimide film, the humidity sensitive polyimide film being produced by reacting: a dianhydride selected from the group consisting of pyromellitic dianhydride and 3,3'-4,4'-benzophenon tetracarboxylic acid dianhydride, with a diamine selected from the group consisting of p-phenylene diamine, m-phenylene diamine, 4,4'-diamino-diphenyl methane, 4,4'-diamino-diphenyl ether, 3,4'-diamino-diphenyl ether and 4,4'-diamino-diphenyl sulfide.
Claim 3
Dependent Claim
21 words
A capacitive humidity sensing element according to claim 1, wherein the dianhydride and the diamine are reacted in a polar solvent.
Claim 4
Dependent Claim
25 words
A capacitive humidity sensing element according to claim 1, wherein the moisture permeable thin gold electrode is vapor deposited onto the humidity sensitive polyimide film.
Claim 5
Dependent Claim
22 words
A capacitive humidity sensing element according to claim 1, wherein the moisture permeable thin gold electrode is formed as a continuous layer.
Claim 6
Dependent Claim
22 words
A capacitive humidity sensing element according to claim 1, wherein the moisture permeable thin gold electrode is formed as a patterned layer.
Claim 7
Dependent Claim
32 words
A capacitive humidity sensing element according to claim 1, wherein the corrosion resistant metal substrate is made of a metal selected from the group consisting of stainless steel, gold, platinum and nickel.
Claim 8
Dependent Claim
22 words
A capacitive humidity sensing element according to claim 6, wherein the corrosion resistant metal substrate is further secured onto an insulating material.
Claim 9
Dependent Claim
22 words
A capacitive humidity sensing element according to claim 7, wherein the metal substrate is vapor deposited onto the moisture sensitive polyimide film.
Claim 10
Dependent Claim
23 words
A capacitive humidity sensing element according to claim 6, wherein the corrosion resistant metal substrate is made of gold and is moisture permeable.
Claim 11
Dependent Claim
109 words
A process for producing a capacitive humidity sensing element comprising the steps of: (i) coating a solution of a dianhydride selected from the group consisting of pyromellitic dianhydride and 3,3'-4,4'-benzophenon tetracarboxylic acid dianhydride, and a diamine selected from the group consisting of p-phenylene diamine, m-phenylene diamine, 4,4'-diamino-diphenyl methane, 4,4'-diamino-phenylene diamine, 4,4'-diamino-diphenyl methane, 4,4'-diamino-diphenyl ether, 3,4'-diamino-diphenyl ether and 4,4'-diamino-diphenyl sulfide in a polar solvent onto a corrosion resistant metal substrate; (ii) heating the coated substrate in stages to a temperature between 200° and 300 ° C. until a humidity sensitive polyimide film is formed on the substrate; and (iii) coating a thin gold layer onto the humidity sensitive polyimide film.
Claim 12
Dependent Claim
109 words
A process for producing a capacitive humidity sensing element comprising the steps of: (i) coating a solution of a dianhydride selected from the group consisting of pyromellitic dianhydride and 3,3'-4,4'-benzophenon tetracarboxylic acid dianhydride, and a diamine selected from the group consisting of p-phenylene diamine, m-phenylene diamine, 4,4'-diamino-diphenyl methane, 4,4'-diamino-phenylene diamine, 4,4'-diamino-diphenyl methane, 4,4'-diamino-diphenyl ether, 3,4'-diamino-diphenyl ether and 4,4'-diamino-diphenyl sulfide in a polar solvent onto a corrosion resistant metal substrate; (ii) heating the coated substrate in stages to a temperature between 200° and 300 ° C. until a humidity sensitive polyimide film is formed on the substrate; and (iii) coating a thin gold layer onto the humidity sensitive polyimide film.
Claim 13
Dependent Claim
12 words
A process according to claim 10, wherein the polar solvent is N-methyl-pyrrolidone.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-08-02 | 1992-02-01 | 1992-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-08-02 | 1996-02-01 | 1996-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-08-02 | 2000-02-01 | 2000-08-02 | $7700.00 | Window Closed / Lapsed |