Sensor for sensing changes in the permittivity of a medium in which it is disposed
First Claim
1. A device for sensing changes in the permittivity of a sample of a medium exposed to an environment having one or more elements, the device comprising:
- an LC oscillator circuit having an inductance element and a capacitance element, the inductance element having a relatively constant value, L, and the capacitance element having a variable value, C, wherein the value of the capacitance element is dependent upon the permittivity of the sample in which the capacitance element is disposed, the LC oscillator circuit having a resonance frequency dependent upon the value of the inductance element and the value of the capacitance element given by the relationship 1/(2π
(LC)1/2), wherein the capacitance element includes first and second conductive elements substantially surrounded by an insulating dielectric material so that the first and second conductive elements are substantially prevented from being exposed to one or more elements of the environment of the sample and so that the first and second conductive elements are prevented from contacting one another, the inductance element having a first lead and a second lead, the first conductive element being electrically coupled to the first lead of the inductance element and the second conductive element being electrically coupled to the second lead of the inductance element; and
,an output circuit coupled to the LC oscillator circuit adapted to output a signal representative of the permittivity of the sample based upon the resonance frequency of the LC oscillator circuit, wherein changes in the output signal are indicative of changes in the permittivity of the sample.
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Abstract
A device for sensing changes in the permittivity of a sample of a monitored medium is disclosed. The monitored medium is exposed to an environment having one or more elements. The device includes an LC oscillator circuit and an output circuit coupled thereto. The LC circuit contains an inductance element and a capacitance element and has a resonance frequency which is dependent upon the permittivity of the sample. The capacitance element includes first and second conductive elements surrounded by an insulating dielectric material so that the first and second conductive elements are prevented from being exposed to one or more elements of the environment of the sample. The output circuit is adapted to output a signal representative of the permittivity of the sample. A method of determining changes in the permittivity of a sample of a medium is also disclosed. The method includes the steps of: (1) disposing a permittivity sensor having an LC oscillator circuit into the medium, the LC oscillator circuit having a resonance frequency dependent upon the permittivity of the sample, wherein the capacitance element includes first and second conductive elements surrounded by an insulating dielectric material, the insulating dielectric material being surrounded by the sample; and, (2) outputting a signal representative of the permittivity of the sample.
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Citations
42 Claims
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1. A device for sensing changes in the permittivity of a sample of a medium exposed to an environment having one or more elements, the device comprising:
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an LC oscillator circuit having an inductance element and a capacitance element, the inductance element having a relatively constant value, L, and the capacitance element having a variable value, C, wherein the value of the capacitance element is dependent upon the permittivity of the sample in which the capacitance element is disposed, the LC oscillator circuit having a resonance frequency dependent upon the value of the inductance element and the value of the capacitance element given by the relationship 1/(2π
(LC)1/2), wherein the capacitance element includes first and second conductive elements substantially surrounded by an insulating dielectric material so that the first and second conductive elements are substantially prevented from being exposed to one or more elements of the environment of the sample and so that the first and second conductive elements are prevented from contacting one another, the inductance element having a first lead and a second lead, the first conductive element being electrically coupled to the first lead of the inductance element and the second conductive element being electrically coupled to the second lead of the inductance element; and
,an output circuit coupled to the LC oscillator circuit adapted to output a signal representative of the permittivity of the sample based upon the resonance frequency of the LC oscillator circuit, wherein changes in the output signal are indicative of changes in the permittivity of the sample. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A device for sensing changes in the permittivity of a sample of a medium exposed to an environment having one or more elements, the device comprising:
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an LC oscillator circuit having an inductance element and a capacitance element, the inductance element having a relatively constant value, L, and the capacitance element having a variable value, C, wherein the value of the capacitance element is dependent upon the permittivity of the sample in which the capacitance element is disposed, the LC oscillator circuit having a resonance frequency dependent upon the value of the inductance element and the value of the capacitance element given by 1/(2π
(LC)1/2), wherein the capacitance element includes a twin-lead cable having first and second conductive elements, wherein twin lead cable includes a dielectric material which substantially surrounds each of its leads, the inductance element having a first lead and a second lead, the first conductive element being electrically coupled to the first lead of the inductance element and the second conductive element being electrically coupled to the second lead of the inductance element; and
,an output circuit coupled to the LC oscillator circuit adapted to output a signal representative of the permittivity of the sample based upon the resonance frequency of the LC oscillator circuit, wherein changes in the output signal are indicative of changes in the permittivity of the sample. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A device for sensing permittivity changes in a sample of a medium, the device comprising:
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an LC oscillator circuit having an inductance element and a capacitance element, the inductance element having a relatively constant value L, and the capacitance element having a variable value, C, wherein the value of the capacitance element is dependent upon the permittivity of the sample in which the capacitance element is disposed, the LC oscillator circuit having a resonance frequency dependent upon the the value of the inductance element and the value of the capacitance element given by 1/(2π
(LC)1/2), wherein the capacitance element includes first and second conductive elements substantially surrounded by an insulating dielectric material, the inductance element having a first lead and a second lead, the first conductive element being electrically coupled to the first lead of the inductance element and the second conductive element being electrically coupled to the second lead of the inductance element; and
,an output circuit coupled to the LC oscillator adapted to output a signal representative of the permittivity of the sample based upon the resonance frequency of the LC oscillator circuit, wherein changes in the output signal are indicative of changes in the permittivity of the sample. - View Dependent Claims (30, 31)
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32. A device for sensing permittivity changes in a sample of a medium, the device comprising:
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an LC oscillator circuit having an inductance element and a capacitance element, the inductance element having a relatively constant value, L, and the capacitance element having a variable value, C, wherein the value of the capacitance element is dependent upon the permittivity of the sample in which the capacitance element is disposed, the LC oscillator circuit having a resonance frequency dependent upon the value of the inductance element and the value of the capacitance element given by 1/(2π
(LC)1/2), wherein the capacitance element includes first and second conductive elements which are separated by an insulating dielectric material along substantially their entire length, the inductance element having a first lead and a second lead, the first conductive element being electrically coupled to the first lead of the inductance element and the second conductive element being electrically coupled to the second lead of the inductance element; and
,an output circuit coupled to the LC oscillator adapted to output a signal representative of the permittivity of the sample based upon the resonance frequency of the LC oscillator circuit, wherein changes in the output signal are indicative of changes in the permittivity of the sample. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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Specification