US3987676A
Expired / Lapsed
US
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Relative humidity detector
Assignee: Individual
•
Filing: 1975-11-28
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Granted: 1976-10-26
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Expires: 1995-11-28
Abstract
Abstract A relative humidity detector, is formed upon a substrate such as glass or amorphous quartz. An aluminum layer evaporated onto the substrate has a layer of Al 2 O 3 anodized thereover to a thickness of 5,000 to 10,000 angstroms. A gold upper metallic layer overlies an adherent layer of chromium upon the Al 2 O 3 to a combined thickness of 1000 Angstroms. After the substrate has been mounted onto an appropriate header, it is submerged in a water bath for about 8 to 12 hours. It is then heated at a temperature of about 120° C. for 6 to 12 hours. The submersion and heating process produces an impedance variation at 1000 Hz which is linear over the relative humidity range of between zero and 100%. In another embodiment, an electrode of gold over chromium evaporated onto a portion of the substrate forms a first electrode. A layer of aluminum evaporated over the substrate and a portion of the first electrode has a layer of Al 2 O 3 thereover. A layer of gold overlying an adherant layer of chromium is formed over a portion of the layer of Al 2 O 3 . A second electrode of gold and chrome overlies an edge portion of the top gold layer, and extends away from it onto the underlying substrate. Electrical connections are made to the first and second electrodes.
Inventors
- 👤 Paul F. Bennewitz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 14:35
CPC Classifications
H; H01; H01C; H01C17/00; H01C17/06; G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/121
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
87 words
A method for making a humidity detector, comprising: forming successive layers of a first electrical conductor, a hygroscopic material consisting essentially of Al 2 O 3 , and a second electrical conductor upon a substrate, whereby the electrical impedance between said first and second electrical conductors varies with variations in humidity, submerging said successive layers into water, and subsequently exposing said successive layers to a temperature of about 120° C., whereby said impedance variation is made essentially linear for variations in relative humidity between 0% and 100%.
Claim 2
Independent Claim
87 words
A method for making a humidity detector, comprising: forming successive layers of a first electrical conductor, a hygroscopic material consisting essentially of Al 2 O 3 , and a second electrical conductor upon a substrate, whereby the electrical impedance between said first and second electrical conductors varies with variations in humidity, submerging said successive layers into water, and subsequently exposing said successive layers to a temperature of about 120° C., whereby said impedance variation is made essentially linear for variations in relative humidity between 0% and 100%.
Claim 3
Dependent Claim
16 words
The method of claim 1 wherein said submerging is for a time of about 12 hours.
Claim 4
Dependent Claim
26 words
The method of claim 1 wherein said heating comprises exposing said successive layers to said temperature for a time of between approximately 6 and 12 hours.
Claim 5
Dependent Claim
55 words
The method of claim 1 wherein said forming successive layers comprises: evaporating a layer of aluminum onto an amorphous quartz substrate, anodizing said aluminum layer to form said layer of Al 2 O 3 , and, evaporating a layer of chrome and a layer of gold onto said layer of Al 2 O 3 .
Claim 6
Dependent Claim
53 words
The method of claim 4 wherein said first layer of aluminum is of thickness of between approximately 15,000 and 20,000 A., said layer of Al 2 O 3 is of thickness of between approximately 5,000 and 10,000 A., and said third layer of chrome and gold is of thickness of about 1,500 A.
Claim 7
Dependent Claim
29 words
The method of claim 1 wherein said step for forming said second electrical conductor comprises providing a material selected from the group consisting of gold, silver, copper and platinum.
Claim 8
Independent Claim
126 words
A method for making a humidity detector, comprising: evaporating an aluminum layer onto a substrate to a depth of between approximately 20,000 and 30,000 A.; forming a layer of Al 2 O 3 upon said substrate of thickness between 5,000 and 10,000 A.; evaporating chrome onto said layer of Al 2 O 3 to a depth of about 700 A.; evaporating gold onto said layer of chrome to a depth of approximately 800 A.; submerging the aforesaid layers into water for about 12 hours; and heating the aforesaid layers at a temperature less than the melting temperature of said Al 2 O 3 to evaporate said water therein and to relieve any intercrystalline stresses therein to produce a linear impedance relationship to humidity of said structure.
Claim 9
Independent Claim
126 words
A method for making a humidity detector, comprising: evaporating an aluminum layer onto a substrate to a depth of between approximately 20,000 and 30,000 A.; forming a layer of Al 2 O 3 upon said substrate of thickness between 5,000 and 10,000 A.; evaporating chrome onto said layer of Al 2 O 3 to a depth of about 700 A.; evaporating gold onto said layer of chrome to a depth of approximately 800 A.; submerging the aforesaid layers into water for about 12 hours; and heating the aforesaid layers at a temperature less than the melting temperature of said Al 2 O 3 to evaporate said water therein and to relieve any intercrystalline stresses therein to produce a linear impedance relationship to humidity of said structure.
Claim 10
Dependent Claim
30 words
The method of claim 7 wherein said heating comprises exposing the aforesaid layers to a temperature of approximately 120° C. for a time of between approximately 6 and 12 hours.
Claim 11
Dependent Claim
12 words
A humidity detector made in accordance with the method of claim 7.
Claim 12
Dependent Claim
12 words
A humidity detector made in accordance with the method of claim 1.
Claim 13
Independent Claim
79 words
A method of linearizing the impedance response of a humidity detector of the type in which successive layers of aluminum, Al 2 O 3 , and gold are formed on a substrate, comprising: submerging said detector into a bath of water, removing said detector from said bath, and exposing said detector to a temperature of approximately 120° C. for a time sufficient to remove all of the water from said bath therein, and to relieve the intercrystalline stresses thereof.
Claim 14
Independent Claim
79 words
A method of linearizing the impedance response of a humidity detector of the type in which successive layers of aluminum, Al 2 O 3 , and gold are formed on a substrate, comprising: submerging said detector into a bath of water, removing said detector from said bath, and exposing said detector to a temperature of approximately 120° C. for a time sufficient to remove all of the water from said bath therein, and to relieve the intercrystalline stresses thereof.
Claim 15
Dependent Claim
23 words
The method of claim 11 wherein said heating step comprises heating said detector for a time of between approximately 6 and 12 hours.
Claim 16
Dependent Claim
153 words
A detector for measuring relative humidity comprising: a header, a substrate, mounted on said header, a layer of aluminum on said substrate of thickness of between approximately 10,000 and 20,000 A., a layer of Al 2 O 3 of thickness no more than 10,000 A., and no less than 5,000 A. on said layer of aluminum, a layer of metal formed on said layer of Al 2 O 3 , said metal layer being selected from the group consisting of gold, platinum, copper and silver, said metal layer being of thickness of about 1,500 A., whereby water molecules from the surrounding air can pass through said metal layer and to said layer of Al 2 O 3 , and a pair of electrodes connected directly to said layer of aluminum and said metal layer, respectively, whereby the impedance of said structure varies linearly with variations in the relative humidity between 0% and 100%.
Claim 17
Dependent Claim
153 words
A detector for measuring relative humidity comprising: a header, a substrate, mounted on said header, a layer of aluminum on said substrate of thickness of between approximately 10,000 and 20,000 A., a layer of Al 2 O 3 of thickness no more than 10,000 A., and no less than 5,000 A. on said layer of aluminum, a layer of metal formed on said layer of Al 2 O 3 , said metal layer being selected from the group consisting of gold, platinum, copper and silver, said metal layer being of thickness of about 1,500 A., whereby water molecules from the surrounding air can pass through said metal layer and to said layer of Al 2 O 3 , and a pair of electrodes connected directly to said layer of aluminum and said metal layer, respectively, whereby the impedance of said structure varies linearly with variations in the relative humidity between 0% and 100%.
Claim 18
Dependent Claim
12 words
The humidity detector of claim 13 wherein said metal layer is gold.
Claim 19
Dependent Claim
12 words
The humidity detector of claim 13 wherein said metal layer is platinum.
Claim 20
Dependent Claim
25 words
The humidity detector of claim 13 wherein said aluminum layer, said Al 2 O 3 layer, and said metal layer are free of intercrystalline stresses.
Claim 21
Dependent Claim
17 words
The humidity detector of claim 13 wherein said aluminum layer is of dimensions approximately 1/8 inch square.
Claim 22
Dependent Claim
71 words
The humidity detector of claim 13 further comprising: an alternating signal generator connected across said metal layer and said aluminum layer, an amplifier connected to receive the signal of said signal generator, and, a thermistor in proximity to said humidity detector connected to said signal generator to vary the gain thereof with variations in temperature, whereby the magnitude of the signal output of said amplifier indicates the impedance of said structure.
Claim 23
Dependent Claim
20 words
The humidity detector of claim 18 wherein said signal of said signal generator is of frequency of approximately 1,000 Hz.
Claim 24
Dependent Claim
33 words
The humidity detector of claim 14 further comprising an layer of chromium between said layer of Al 2 O 3 and said layer of gold of thickness of approximately 200 to 500 A.
Claim 25
Dependent Claim
197 words
A detector for measuring relative humidity comprising: a header, a substrate mounted on said header, a first electrode evaporated onto a portion of said substrate, a layer of aluminum on a portion of said substrate, overlying at least a portion of said first electrode, said layer of aluminum being of thickness between approximately 10,000 and 20,000 A., a layer of Al 1 O 3 of thickness of no more than 10,000 A. on said layer of aluminum, a layer of metal formed on said layer of Al 2 O 3 , said metal layer being selected from the group consisting of gold, platinum, copper and silver, said metal layer being of thickness of about 1,500 A., whereby water molecules from the surrounding air can pass through said metal layer and to said layer of Al 2 O 3 , a second electrode on said substrate, in contact with said layer of metal formed on said layer of Al 2 O 3 , and a pair of electrodes bonded to said first and second electrodes, respectively, whereby the impedance of said structure measured upon said electrodes varies linearly with variations in the relative humidity between zero and 100%.
Claim 26
Dependent Claim
197 words
A detector for measuring relative humidity comprising: a header, a substrate mounted on said header, a first electrode evaporated onto a portion of said substrate, a layer of aluminum on a portion of said substrate, overlying at least a portion of said first electrode, said layer of aluminum being of thickness between approximately 10,000 and 20,000 A., a layer of Al 1 O 3 of thickness of no more than 10,000 A. on said layer of aluminum, a layer of metal formed on said layer of Al 2 O 3 , said metal layer being selected from the group consisting of gold, platinum, copper and silver, said metal layer being of thickness of about 1,500 A., whereby water molecules from the surrounding air can pass through said metal layer and to said layer of Al 2 O 3 , a second electrode on said substrate, in contact with said layer of metal formed on said layer of Al 2 O 3 , and a pair of electrodes bonded to said first and second electrodes, respectively, whereby the impedance of said structure measured upon said electrodes varies linearly with variations in the relative humidity between zero and 100%.
Claim 27
Dependent Claim
12 words
The humidity detector of claim 20 wherein said metal layer is gold.
Claim 28
Dependent Claim
25 words
The humidity detector of claim 20 wherein said aluminum layer, said Al 2 O 3 layer and said metal layer are free of intercrystalline stresses.
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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) | 1979-10-26 | 1980-04-26 | 1980-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-10-26 | 1984-04-26 | 1984-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-10-26 | 1988-04-26 | 1988-10-26 | $7700.00 | Window Closed / Lapsed |