Electrical sensor for sensing moisture in soils
First Claim
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1. A sensor for sensing moisture in soil, comprising:
- a conductive metal housing having a wall which forms an internal cavity, said wall having a plurality of perforations therethrough;
a porous filter liner lining said wall in said cavity;
a granular transfer matrix comprising silica sand contained by said liner;
a buffer tablet of compacted gypsum abutting said transfer matrix;
an electrode matrix comprising silica sand abutting said buffer tablet;
a pair of electrodes in contact with said electrode matrix, said electrodes being spaced apart from one another, and bridged by said electrode matrix; and
a lead extending from each of said electrodes;
said sensor being closed against entry of moisture except through said perforations, whereby moisture from soil in contact with said liner penetrates said liner and transfer matrix and passes through said tablet, dissolving some electrolyte as it does, and enters said electrode matrix so as to form an electrically conductive path between said electrodes, the conductivity or lack of conductivity of the electrode matrix between the electrodes being indicative of the presence or absence of moisture in the soil contiguous to the sensor.
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Abstract
A soil moisture sensor to be implanted in soil. The sensor has a conductive metal housing, perforated to pass moisture to and through a filter liner which lines an internal cavity. A transfer matrix is confined in the liner and is abutted by a buffer tablet of compacted gypsum. An electrode matrix abuts the tablet and bridges a pair of spaced-apart electrodes. Water, or absence of water, in the electrode matrix provides a measure of moisture in the soil as a function of electrical conductivity between the electrodes.
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Citations
7 Claims
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1. A sensor for sensing moisture in soil, comprising:
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a conductive metal housing having a wall which forms an internal cavity, said wall having a plurality of perforations therethrough; a porous filter liner lining said wall in said cavity; a granular transfer matrix comprising silica sand contained by said liner; a buffer tablet of compacted gypsum abutting said transfer matrix; an electrode matrix comprising silica sand abutting said buffer tablet; a pair of electrodes in contact with said electrode matrix, said electrodes being spaced apart from one another, and bridged by said electrode matrix; and a lead extending from each of said electrodes; said sensor being closed against entry of moisture except through said perforations, whereby moisture from soil in contact with said liner penetrates said liner and transfer matrix and passes through said tablet, dissolving some electrolyte as it does, and enters said electrode matrix so as to form an electrically conductive path between said electrodes, the conductivity or lack of conductivity of the electrode matrix between the electrodes being indicative of the presence or absence of moisture in the soil contiguous to the sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification