US4373391A
Expired / Lapsed
US
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Relative humidity sensitive material
Assignee: General Electric Co
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Filing: 1981-04-24
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Granted: 1983-02-15
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Expires: 2001-04-24
Abstract
Abstract A relative humidity sensitive material comprises a mixture of at least one hygroscopic salt and an at least partially electrically conductive metal based powder. Each salt in the relative humidity sensitive material has a cationic constituent selected from the group consisting of the alkali and alkaline earth metals and an anionic constituent selected from the group consisting of a chlorate, perchlorate, and chloro aluminate. The metal based powder preferably comprises a metal or metal oxide powder or powder mixture including such constituents as Zr, CO 3 O 4 , and MnO 2 . Additionally, the material may include a binding agent and a slurry mixture may be formed for placement of the resultant material between electrodes on a substrate so as to form a relative humidity sensor. These sensors are employed either individually or configured in a system used to either indicate or control the relative humidity.
Inventors
- 👤 Peter D. Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:58
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/121; Y; Y10; Y10S; Y10S252/00; Y10S252/963
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
82 words
A relative humidity sensitive material comprising: a mixture of at least one hygroscopic salt; an at least partially electrically conductive metal based powder comprising a mixture of materials selected from the group consisting of Co 3 O 4 , Zr, and MnO 2 ; each said salt having a cationic constituent selected from the group consisting of the alkali and alkaline earth metals and an anionic constituent selected from the group consisting of chlorate, perchlorate, and chloro aluminate; and an inert binder.
Claim 2
Dependent Claim
82 words
A relative humidity sensitive material comprising: a mixture of at least one hygroscopic salt; an at least partially electrically conductive metal based powder comprising a mixture of materials selected from the group consisting of Co 3 O 4 , Zr, and MnO 2 ; each said salt having a cationic constituent selected from the group consisting of the alkali and alkaline earth metals and an anionic constituent selected from the group consisting of chlorate, perchlorate, and chloro aluminate; and an inert binder.
Claim 3
Dependent Claim
15 words
The relative humidity sensitive material of claim 1 in which said inert binder comprises polyvinylpyrollidone.
Claim 4
Dependent Claim
29 words
The relative humidity sensitive material of claim 1 in which said salt, metal based powder, and binder are present in the approximate weight ratio of ×:0.85:0.01, respectively, where 0.05≦×≦0.25.
Claim 5
Dependent Claim
31 words
The relative humidity sensitive material of claim 1 in which said at least partially electrically conductive metal based powder comprises a mixture of Zr powder and Co 3 O 4 powder.
Claim 6
Dependent Claim
28 words
The relative humidity sensitive material of claim 4 in which the weight ratio of Zr powder to Co 3 O 4 powder is between approximately 0.2 and 0.8.
Claim 7
Dependent Claim
22 words
The relative humidity sensitive material of claim 4 in which the particles of Zr powder have a diameter of approximately 25 microns.
Claim 8
Dependent Claim
34 words
The relative humidity sensitive material of claim 5 in which the Zr powder and the Co 3 O 4 powder are approximately present in the weight ratio of 0.45:0.40 with respect to each other.
Claim 9
Dependent Claim
152 words
The relative humidity sensitive material of claim 1 in which said at least one salt is selected from the group consisting of KClO 4 and NaClO 4 in the approximate weight ratio of 0.1 to 0.13, respectively; KClO 4 and NaClO 4 in the approximate weight ratio of 0.1 to 0.05, respectively; Ca(ClO 3 ) 2 .2H 2 O and NaClO 3 in the approximate weight ratio of 0.04 to 0.12, respectively; Ca(ClO 3 ) 2 .2H 2 O and NaClO 3 in the approximate weight ratio of 0.02 to 0.12, respectively; Ba(ClO 3 ) 2 .H 2 O and NaClO 3 in the approximate weight ratio of 0.15 to 0.06; respectively, and NaClO 3 in the approximate weight ratio of 0.15, each of the weight ratios being given with respect to said metal based powder which is present in the approximate weight ratio of 0.85 with respect to the above ratios.
Claim 10
Dependent Claim
27 words
The relative humidity sensitive material of claim 8 wherein the inert binder is hydrophilic and present in the weight ratio of between approximately 0.005 and approximately 0.02.
Claim 11
Dependent Claim
53 words
A relative humidity sensor exhibiting changes in impedance in response to changes in relative humidity, said sensor comprising an inert substrate with a pair of spaced apart electrodes disposed thereon with the relative humidity sensitive material of claim 1 affixed to said substrate between said electrodes and in electrical contact with said electrodes.
Claim 12
Dependent Claim
23 words
The relative humidity sensor of claim 10 in which said substrate comprises material selected from the group consisting of glass and porous ceramic.
Claim 13
Dependent Claim
69 words
A relative humidity sensing system comprising: a plurality of sensors of claim 10, each of said sensors being particularly responsive to changes in relative humidity in a specific relative humidity range; and means to select at least one of said sensors, said selection depending on ambient relative humidity conditions; means to convert the impedance of said at least one selected sensor so as to indicate said ambient relative humidity.
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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) | 1986-02-14 | 1986-08-16 | 1987-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-14 | 1990-08-16 | 1991-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-14 | 1994-08-16 | 1995-02-15 | $7700.00 | Window Closed / Lapsed |