US4975249A
Expired / Lapsed
US
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Optical and capacitance type, phase transition, humidity-responsive devices
Assignee: Individual
•
Filing: 1989-12-01
•
Granted: 1990-12-04
•
Expires: 2009-12-01
Abstract
Abstract The invention provides novel chemical compositions for use in primary, optical/capacitance hygrometric devices. It also provides methods for using these compositions as sensors for the precise measurements of the humidity of gases as well as the apparatus. The chemical compositions, which of themselves sense the change in water vapor pressure, are birefringent, translucent, and anisotropic at a first water vapor pressure/temperature, but non-birefringent, optically clear, and isotropic at a second vapor pressure/temperature. Optical changes which accompany these phase changes may be amplified. Some compositions, exhibit abrupt and large increases in their dielectric constant coincident with the optical changes which occur at the phase shift point. Others show a large and precisely linear change in dielectric constant over many decades of relative humidity (RH), but the optical shift occurs at a precise point within the range. By noting the capacitance readout from a prestandardized combination optical/capacitance hygrometric device at the moment of optically indicated phase shift (when the system changes from isotropic to birefringent), any drift in the electronics of the device can be immediately detected since the sensor's phase shift point is invariant. If it is desired to eliminate polarizer amplifiers because of their cost, sensor substrates can be shaped so that internal reflection within the substrate and optical coupling of the birefringent sensor to the substrate generate excellent optical signals at the sensor's trigger points. The devices and methods of the new hygrometry allow many variations on the primary requirements. If desire, the sensor can be made an integral part of a capacitance-sensitive IC.
Inventors
- 👤 Stanley B. Elliott
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:18
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/75; G01N21/77; G01N21/78; G01N21/81; G01N27/00; G01N27/02; G01N27/22; G01N27/223; G01N27/225; Y; Y10; Y10S; Y10S252/00; Y10S252/963
Claims Analysis
Total Claims: 45
Claim 1
Independent Claim
245 words
A combination optical and capacitance humidity-responsive device for selectively and directly monitoring optical and electrical changes in a chemical composition comprising (1) a source of illumination providing a light beam, (2) a chemical composition comprising a lyotropic liquid crystal salt having an organic ring portion that is hydrophobic and a polar head that is hydrophilic and which of itself reversibly senses changes in humidity, the combination being triggered optically at a particular water vapor pressure/temperature from an anisotropic and translucent liquid crystal state characteristic of a first water vapor pressure/temperature condition immediately contiguous to said particular water vapor pressure/temperature to an isotropic and transparent liquid state characteristic of the particular water vapor pressure/temperature, while its dielectric constant is changing substantially and reproducibly as the water vapor pressure/temperature changes, (3) light detecting means for detecting observable changes in the brightness and intensity of the light coming from the composition when the light beam contacts the composition, the light from the composition at the first water vapor pressure/temperature being of sufficient brightness and intensity to provide a visual signal at the first water vapor pressure/temperature but not at the particular water vapor pressure/temperature, (4) electrode means insulated from the composition and capacitively associated therewith and means for impressing a voltage across said electrode means and (5) electrical capacitance measuring means connected to said electrode means for measuring changes in the dielectric constant of the composition in response to changes in the water vapor pressure/temperature of said composition.
Claim 2
Dependent Claim
245 words
A combination optical and capacitance humidity-responsive device for selectively and directly monitoring optical and electrical changes in a chemical composition comprising (1) a source of illumination providing a light beam, (2) a chemical composition comprising a lyotropic liquid crystal salt having an organic ring portion that is hydrophobic and a polar head that is hydrophilic and which of itself reversibly senses changes in humidity, the combination being triggered optically at a particular water vapor pressure/temperature from an anisotropic and translucent liquid crystal state characteristic of a first water vapor pressure/temperature condition immediately contiguous to said particular water vapor pressure/temperature to an isotropic and transparent liquid state characteristic of the particular water vapor pressure/temperature, while its dielectric constant is changing substantially and reproducibly as the water vapor pressure/temperature changes, (3) light detecting means for detecting observable changes in the brightness and intensity of the light coming from the composition when the light beam contacts the composition, the light from the composition at the first water vapor pressure/temperature being of sufficient brightness and intensity to provide a visual signal at the first water vapor pressure/temperature but not at the particular water vapor pressure/temperature, (4) electrode means insulated from the composition and capacitively associated therewith and means for impressing a voltage across said electrode means and (5) electrical capacitance measuring means connected to said electrode means for measuring changes in the dielectric constant of the composition in response to changes in the water vapor pressure/temperature of said composition.
Claim 3
Dependent Claim
36 words
A device as defined in claim 1 in which the composition is birefringent at the immediately contiguous water vapor pressure/temperature when in a liquid crystal state and non-birefringent at the particular water vapor pressure/temperature when liquid.
Claim 4
Dependent Claim
43 words
A device as defined in claim 1 in which the means for detecting observable changes includes means for illuminating the composition which when translucent at the immediately contiguous water vapor pressure/temperature provides light of sufficient intensity and brightness to provide a visual signal.
Claim 5
Dependent Claim
39 words
A device as defined in claim 1 in which the light detecting means includes electrical means responsive to the visual signal at the immediately contiguous water vapor pressure/temperature and non-responsive to the signal at the particular water vapor pressure/temperature.
Claim 6
Dependent Claim
20 words
A device as defined in claim 1 in which the electrical capacitance measuring means is calibrated in percent relative humidity.
Claim 7
Dependent Claim
53 words
A device as defined in claim 1 and wherein the electrical capacitance measuring means includes an LED activated by the light detecting means to visually indicate that said particular water vapor pressure/temperature has been reached to thereby confirm the operation of the electronic circuitry in its measurement of both optical and electrical parameters.
Claim 8
Dependent Claim
36 words
A device as defined in claim 1 in which the chemical composition is a mixture of an alkali metal salt of 3-benzoylpropionic acid and a lattice modifier which is an alkali metal salt of hydroxybutyric acid.
Claim 9
Dependent Claim
55 words
A device as defined in claim 1 in which the chemical composition is a mixture of an alkali metal salt of 3-benzoylpropionic acid and a lattice modifier which is an alkali metal salt of one or more carboxylic acids selected from the group consisting of malonic, tartronic, succinic, levulinic, ketoglutaric, hydroxybutyric, succinamic, and aminobutyric acids.
Claim 10
Dependent Claim
27 words
A device as defined in claim 1 in which the chemical composition comprises a mixture of an alkali metal salt of 3-benzoylpropionic acid and 3-(4-ethylbenzoyl) propionic acid.
Claim 11
Dependent Claim
34 words
A device as defined in claim 1 in which the saturated aqueous solution of the composition has a vapor pressure in the range of about 0.1 to 17.5 mm. of mercury of 20° C.
Claim 12
Dependent Claim
26 words
A device as defined in claim 1 in which the composition is a coating of approximately 0.01 mm. thickness on a translucent or transparent, isotropic substrate.
Claim 13
Dependent Claim
146 words
A device as defined in claim 1 in which the chemical composition is a mixture of the alkali metal salts of 3-benzoylpropionic acid, of a lattice modifier which is an alkali metal salt of hydroxybutyric acid, of a lattice stabilizer comprising an alkali metal salt of a perfluoroalkyl acid phosphate at a concentration of 0.1 to 0.3% by weight, on the basis of solids, and of a complex comprising (a) a water-soluble salt of Cu ++ at a concentration of 0.4 to 5.0 mol percent of the metals present in the chemical composition, (b) an alkali metal salt of polyacrylic acid in a concentration of from 2.0 to 8.0% by weight for each 8% of the alkali metal salt of the 3-benzoylpropionic acid, and (c) an alkali metal borate in concentration of from 0.25 to 10.0 mol percent of the metals present in the chemical composition.
Claim 14
Dependent Claim
19 words
A device as defined in claim 1 in which the composition is the potassium salt of 3-benzoyl propionic acid.
Claim 15
Dependent Claim
32 words
A device as defined in claim 13 in which the composition is translucent at the immediately contiguous water vapor pressure/temperature when less hydrated transparent at the particular water vapor pressure/temperature when hydrated.
Claim 16
Dependent Claim
32 words
A device as defined in claim 13 in which the composition is translucent at the immediately contiguous water vapor pressure/temperature when crystalline and transparent at the particular water vapor pressure/temperature when liquid.
Claim 17
Dependent Claim
41 words
A device as defined in claim 1 in which the capacitance measuring means includes adjustable electrical means responsive to the capacitance signal at the immediately contiguous water vapor pressure/temperature but non-responsive to the capacitance signal at the particular water vapor pressure/temperature.
Claim 18
Dependent Claim
31 words
A device as defined in claim 16 in which the electrical means includes control means that is responsive to the capacitance signal for controlling electrical power to activate an electrical circuit.
Claim 19
Dependent Claim
168 words
A capacitance, humidity-responsive device comprising means for providing observable changes in humidity comprising (1) a chemical composition comprising a lyotropic liquid crystal salt having an organic ring portion that is hydrophobic and a polar head that is hydrophilic and which of itself reversibly senses changes in humidity, the composition being triggered optically at a particular water vapor pressure/temperature from an anisotropic and translucent liquid crystal state characteristic of a first water vapor pressure/temperature condition immediately contiguous to said particular water vapor pressure/temperature to an isotropic and transparent liquid state characteristic of the particular water vapor pressure/temperature, while its dielectric constant is changing substantially and reproducibly as the water vapor pressure/temperature changes, (2) electrode means insulated from the composition and capactively associated with said composition, and electrical means for impressing a voltage across said electrode means, and (3) electrical capacitance measuring means connected to said electrode means for measuring changes in the dielectric constant of the composition in response to changes in the water vapor pressure/temperature of said composition.
Claim 20
Dependent Claim
168 words
A capacitance, humidity-responsive device comprising means for providing observable changes in humidity comprising (1) a chemical composition comprising a lyotropic liquid crystal salt having an organic ring portion that is hydrophobic and a polar head that is hydrophilic and which of itself reversibly senses changes in humidity, the composition being triggered optically at a particular water vapor pressure/temperature from an anisotropic and translucent liquid crystal state characteristic of a first water vapor pressure/temperature condition immediately contiguous to said particular water vapor pressure/temperature to an isotropic and transparent liquid state characteristic of the particular water vapor pressure/temperature, while its dielectric constant is changing substantially and reproducibly as the water vapor pressure/temperature changes, (2) electrode means insulated from the composition and capactively associated with said composition, and electrical means for impressing a voltage across said electrode means, and (3) electrical capacitance measuring means connected to said electrode means for measuring changes in the dielectric constant of the composition in response to changes in the water vapor pressure/temperature of said composition.
Claim 21
Dependent Claim
37 words
A device as defined in claim 18 in which all elements of the device have been miniaturized, and the electrical capacitance measuring means for measuring changes in the dielectric constant of the composition is an intergrated circuit.
Claim 22
Dependent Claim
86 words
A humidity-responsive device as defined in claims 1 or 18 and wherein the chemical composition comprises one or more alkali metal salts of an acid of the general formula R-Aryl-CO-X-(CH 2 ) Y -CO 2 H, where R is hydrogen, halogen, alkyl, alkoxy, or nitro, where Aryl is phenyl or a connected ring structure or a fused ring structure, where X is a nitrogen or a carbon attached to the adjacent methylene with either a single or double bond, and where Y is 0 to 7.
Claim 23
Independent Claim
46 words
A device as defined in claims 1 or 18 in which at least two discrete adjacent areas capacitively associated with the electrode means are occupied with compositions comprising a series of compounds or mixtures of compounds which trigger at different water vapor pressures at 20° C.
Claim 24
Independent Claim
39 words
A device as defined in claims 1 or 18 in which the chemical composition contains before coating from 10-50% by weight of sensor solids compounded with from 0.5 to 4.0% by weight of inorganic compounds of high surface area.
Claim 25
Dependent Claim
219 words
An optical humidity-responsive device comprising (1) a source of illumination providing a light beam, (2) means for providing observable changes in humidity comprising a chemical composition which comprises one or more alkali metal salts of an acid of the general formula R-Aryl-CO-X-(CH 2 ) Y -CO 2 H, where R is hydrogen, halogen, alkyl, alkoxy, or nitro, where Aryl is phenyl or a connected ring structure or a fused ring structure, where X is a nitrogen or a carbon attached to the adjacent methylene with either a single or a double bond, and where Y is 0 to 7 and which composition of itself reversibly senses changes in humidity, said composition being triggered optically at a particular water vapor pressure/temperature from an anisotropic and translucent phase characteristic of a first water vapor pressure/temperature condition immediately contiguous to said particular water vapor pressure/temperature to an isotropic and transparent phase characteristic of the particular water vapor pressure/temperature, and (3) light detecting means for detecting observable changes in the brightness and intensity of the light coming from the composition when the light beam contacts the composition, the light from the composition at the first water vapor pressure/temperature being of sufficient brightness and intensity to provide a visual signal at the first water vapor pressure/temperature but not at the particular water vapor pressure/temperature.
Claim 26
Dependent Claim
219 words
An optical humidity-responsive device comprising (1) a source of illumination providing a light beam, (2) means for providing observable changes in humidity comprising a chemical composition which comprises one or more alkali metal salts of an acid of the general formula R-Aryl-CO-X-(CH 2 ) Y -CO 2 H, where R is hydrogen, halogen, alkyl, alkoxy, or nitro, where Aryl is phenyl or a connected ring structure or a fused ring structure, where X is a nitrogen or a carbon attached to the adjacent methylene with either a single or a double bond, and where Y is 0 to 7 and which composition of itself reversibly senses changes in humidity, said composition being triggered optically at a particular water vapor pressure/temperature from an anisotropic and translucent phase characteristic of a first water vapor pressure/temperature condition immediately contiguous to said particular water vapor pressure/temperature to an isotropic and transparent phase characteristic of the particular water vapor pressure/temperature, and (3) light detecting means for detecting observable changes in the brightness and intensity of the light coming from the composition when the light beam contacts the composition, the light from the composition at the first water vapor pressure/temperature being of sufficient brightness and intensity to provide a visual signal at the first water vapor pressure/temperature but not at the particular water vapor pressure/temperature.
Claim 27
Dependent Claim
17 words
An optical humidity-responsive device as defined in claim 23 and wherein the connected ring structure is biphenyl.
Claim 28
Dependent Claim
27 words
An optical humidity-responsive device as defined in claim 23 and wherein the fused ring structure is of the group consisting of naphthalene, acenaphthene, fluorene, anthracene and pyrene.
Claim 29
Dependent Claim
52 words
A device as defined in claim 23 and comprising a rectangularly shaped solid, isotropic material having a cross-section which causes internal reflection of light when such light is directed to its front, at least 25% of the device's back side being coated with the composition having a thickness of approximately 0.01 mm.
Claim 30
Dependent Claim
26 words
A device as defined in claim 26 in which the cross-section of the isotropic material is one of the group consisting of semi-circular, semi-annular or trapezoidal.
Claim 31
Dependent Claim
34 words
A device as defined in claim 26 and wherein the selected cross-section is trapezoidal and the angles of the trapezoid being selected so as to secure total internal reflection of light within the material.
Claim 32
Dependent Claim
80 words
A device as defined in claim 20 or 23 in which the trigger point of the chemical composition is reduced to a lower water vapor pressure/temperature through the inclusion of a lattice modifier which comprises one or more of the alkali metal salts of an acid of the general formula R-CZ-(CH 2 ) Y -CO 2 H, where R is amino, hydroxyl, carboxyl, or methyl, where Z is hydrogen, hydroxyl, or a keto, and where Y is 0 to 4.
Claim 33
Independent Claim
65 words
A device as defined in claims 23 or 20 in which the composition is optically stabilized through the inclusion of from 1.0 to 3.0% by weight, on the basis of solids of a lattice stabilizer which comprises a low vapor pressure aryl hydrocarbon from the group consisting of: hydrogenated terphenyl, terphenyl, 1,1-di(orho-xylyl) ethane, 1,2,3,4 tetramethyl benzene, 1,2,4,5 tetramethylbenzene, 1,2,3,5 tetramethyl benzene, 1,2,3,4,5 pentamethylbenzene, and cyclohexylbenzene.
Claim 34
Independent Claim
56 words
A device as defined in claims 23 or 20 in which the composition is optically stabilized through the inclusion of from 0.1 to 0.3% by weight, on the basis of solids, of a lattice stabilizer from the group consisting of alkali metal perfluoralkyl sulfonates, carboxylates, and acid phosphates, whose fluorocarbon chains contain 3 to 5 carbons.
Claim 35
Independent Claim
126 words
A device as defined in claims 23 or 20 in which the chemical composition is complexed with from 0.4 to 5.0 mol percent of the metals present of a water-soluble salt of a polyvalent cation selected from the group consisting of Cu ++ , Ni ++ , Co ++ , Mn ++ , Al +++ , Zn ++ , and Cr +++ , and in which each 8% of alkali metal sensor salt is complexed with from 2.0 to 8.0% by weight of a polymer which has repetitive carboxyl groups whose acidic hydrogens have been replaced by alkali metal cations, and in which the chemical composition is complexed with an alkali metal borate in an amount from 0.25 to 10.0 mol percent of the metals present.
Claim 36
Independent Claim
21 words
A device as defined in claims 23 or 20 in which the composition comprises an alkali metal salt of 3-benzoylpropionic acid.
Claim 37
Independent Claim
23 words
A device as defined in claims 23 or 20 in which the composition comprises mixtures of the alkali metal salts of 3-benzoylpropionic acid.
Claim 38
Independent Claim
22 words
A device as defined in claims 23 or 20 in which the composition comprises an alkali metal salt of 3-(4-ethylbenzoyl) propionic acid.
Claim 39
Independent Claim
24 words
A device as defined in claims 23 or 20 in which the composition comprises mixtures of the alkali metal salts of 3-(4-ethylbenzoyl) propionic acid.
Claim 40
Dependent Claim
260 words
An optical humidity-responsive device comprising (1) a source of illumination providing a light beam, (2) means for providing observable changes in humidity comprising a chemical composition which comprises one or more alkali metal salts of an acid of the general formula R-Aryl-CO-X-(CH 2 ) Y -CO 2 H, where R is one of the group consisting of hydrogen, halogen, alkyl, alkoxy, or nitro, where Aryl is phenyl or a connected ring structure or a fused ring structure, where X is a nitrogen or a carbon attached to the adjacent methylene with either a single or a double bond, and where Y is 0 to 7 and which composition of itself reversibly senses changes in humidity, said composition being triggered optically at a particular water vapor pressure/temperature from an anisotropic and translucent phase characteristic of a first water vapor pressure/temperature condition immediately contiguous to said particular water vapor pressure/temperature to an isotropic and transparent phase characteristic of the particular water vapor pressure/temperature, (3) means to amplify observable changes in the composition due to changes in the humidity including a polarizer for the light beam and an analyzer for the polarized beam that is passed through the composition, and (4) light detecting means for detecting observable changes in the brightness and intensity of the light coming from the composition when the light beam contacts the composition, the light from the composition at the first water vapor pressure/temperature being of sufficient brightness and intensity to provide a visual signal at the first water vapor pressure/temperature but not at the particular water vapor pressure/temperature.
Claim 41
Dependent Claim
260 words
An optical humidity-responsive device comprising (1) a source of illumination providing a light beam, (2) means for providing observable changes in humidity comprising a chemical composition which comprises one or more alkali metal salts of an acid of the general formula R-Aryl-CO-X-(CH 2 ) Y -CO 2 H, where R is one of the group consisting of hydrogen, halogen, alkyl, alkoxy, or nitro, where Aryl is phenyl or a connected ring structure or a fused ring structure, where X is a nitrogen or a carbon attached to the adjacent methylene with either a single or a double bond, and where Y is 0 to 7 and which composition of itself reversibly senses changes in humidity, said composition being triggered optically at a particular water vapor pressure/temperature from an anisotropic and translucent phase characteristic of a first water vapor pressure/temperature condition immediately contiguous to said particular water vapor pressure/temperature to an isotropic and transparent phase characteristic of the particular water vapor pressure/temperature, (3) means to amplify observable changes in the composition due to changes in the humidity including a polarizer for the light beam and an analyzer for the polarized beam that is passed through the composition, and (4) light detecting means for detecting observable changes in the brightness and intensity of the light coming from the composition when the light beam contacts the composition, the light from the composition at the first water vapor pressure/temperature being of sufficient brightness and intensity to provide a visual signal at the first water vapor pressure/temperature but not at the particular water vapor pressure/temperature.
Claim 42
Dependent Claim
53 words
A device as defined in claim 37 in which the device is a transmission type in which the light beam passes through the polarizer and the polarized light beam passes through the composition, where it is doubly refracted at the first water vapor pressure/temperature, and the emerging refracted beam passes through the analyzer.
Claim 43
Dependent Claim
40 words
A device as defined in claim 37 in which the device is a reflective type, the light beam passes through a circular polarizer and the composition to a mirror and then being reflected back through the composition and the analyzer.
Claim 44
Dependent Claim
15 words
A device as defined in claim 37 and wherein the connected ring structure is biphenyl.
Claim 45
Dependent Claim
25 words
A device as defined in claim 37 and wherein the fused ring structure is of the group consisting of naphthalene, acenaphthene, fluorene, anthracene and pyrene.
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