RAPID RESPONSE SOIL MOISTURE DETECTION SYSTEM

Abstract

RAPID RESPONSE SOIL MOISTURE DETECTION SYSTEM The present invention relates to a soil moisture sensor designed for rapid and accurate detection of moisture levels in soil. The sensor comprises a rigid, electrically conductive metal housing with an inner wall that forms a cavity for holding a transmission medium. The housing includes perforations to allow soil moisture to pass through. A water-permeable liner, made of thermally bonded fibers, lines the inner wall and covers the perforations. This liner is specifically designed to retain the transmission medium while facilitating the flow of moisture into the cavity. The cavity is filled with a transmission medium, which is a mixture of granular gypsum, a slowly dissolving material, combined with a particulate matrix such as ceramic, sand, or silica. Within the transmission medium, a pair of spaced-apart electrodes is positioned, with electrical leads extending through a cap (21) at the top of the housing. The electrodes measure the conductivity of the medium, which varies based on the moisture content, providing a reliable indicator of soil moisture levels. This innovative design ensures efficient moisture transfer, reduces delays in measurement, and enhances the sensor’s durability and performance. The sensor is particularly suitable for applications requiring precise soil moisture monitoring, such as agriculture and environmental management.

Specification

Description:Field and background of the Invention:
The present invention relates to soil moisture sensors, specifically a rapid-response soil moisture system utilizing gypsum granules for enhanced performance. This innovative design allows for the efficient and accurate measurement of soil moisture in a significantly reduced timeframe.
While prior art documents and technologies are referenced in this description, such references should not be construed as an acknowledgment of their existence or widespread use in India or as part of general knowledge before the priority date of this invention.
Soil moisture sensors have been widely developed by various manufacturers and are primarily employed to measure soil hydration levels. However, conventional designs often exhibit limitations in response time and accuracy, particularly under varying soil and environmental conditions.
The current invention addresses these challenges with a novel design. It features a perforated, rigid housing made of electrically conductive metal or alloy, which resists crushing under external loads. This housing encloses an internal cavity filled with a transmission granular matrix. A liner provides a seamless interface between this granular matrix and the surrounding soil.
A key feature of the design is the inclusion of a gypsum buffer tablet, which separates the transmission matrix chamber from the electrode matrix chamber. The latter contains a pair of spaced-apart electrodes embedded in an electrode chamber matrix. Moisture is transferred from the transmission matrix to the electrode matrix through the gypsum tablet, ensuring effective sensor functionality.
However, traditional systems relying on similar configurations face significant delays in moisture detection and drying cycles. This occurs due to the slow dissolution of the gypsum buffer, leading to inaccurate or delayed moisture readings, which can compromise the performance of irrigation controllers.
The inventive sensor resolves these issues by optimizing the material composition and structural integration of the gypsum buffer and transmission matrices. This ensures rapid moisture transmission, reduced time delays, and improved electrical conductivity between electrodes, even under pure water conditions. As a result, the sensor delivers reliable, real-time data for efficient irrigation management.



 
Objectives of the Invention:
1. To Develop a Rapid-Response Soil Moisture Sensor
To design and implement an advanced soil moisture sensor capable of providing rapid and accurate soil moisture measurements.
2. To Address Limitations in Prior Art
To overcome the delays and inaccuracies associated with conventional soil moisture sensors, particularly those caused by slow moisture transmission and drying cycles.
3. To Enhance Sensor Efficiency with Gypsum Granules
To incorporate gypsum granules as a critical component for improved moisture transmission and electrical conductivity between electrodes, ensuring reliable performance under varied conditions.
4. To Reduce Moisture Sensing Delays
To minimize time delays in detecting and transmitting soil moisture data by optimizing the design and material composition of the transmission and electrode matrices.
5. To Improve Data Accuracy for Irrigation Systems
To provide consistent and precise soil moisture data for effective control of irrigation systems, eliminating erroneous readings caused by delayed sensor response.
6. To Ensure Durability and Robustness
To design a sensor housing resistant to external loads, ensuring long-term durability and functionality in diverse soil environments.
7. To Facilitate Efficient Integration into Agricultural Systems
To enable seamless adoption and integration of the sensor in modern agricultural and irrigation systems, enhancing water resource management.
 
Prior art patents are described below:
US Patent No: US5179347A - Electrical Sensor for Sensing Moisture in Soils
One of the prior art devices is a soil moisture sensor designed for implantation in the soil. This sensor features a conductive metal housing with perforations that allow moisture to pass through and interact with an internal structure. Inside the housing, a filter liner forms an internal cavity containing a transfer matrix for moisture transmission.
Adjacent to the transfer matrix is a buffer tablet made of compacted gypsum, which separates it from an electrode matrix. The electrode matrix, in turn, connects to a pair of spaced-apart electrodes, facilitating the measurement of soil moisture. The sensor operates by detecting the presence or absence of water in the electrode matrix, which influences the electrical conductivity between the electrodes. The resulting conductivity data serves as an indicator of soil moisture levels.
While this design has been effective in providing moisture readings, it exhibits certain limitations, particularly in response time and the accuracy of transmitted data, due to the properties of the buffer tablet and moisture transmission mechanism. These shortcomings necessitate advancements to address delays and improve real-time soil moisture monitoring.
US Patent No: US7705616B2 - Sensor for Sensing Moisture in Soils
1. Conductive Housing: The sensor includes an electrically conductive metal housing with walls forming an internal cavity for a transmission matrix. The housing walls are perforated to allow moisture to pass through.
2. Liner for Moisture Transmission: The inside wall of the housing is lined with a water-transmissible liner that covers the perforations. This liner is designed to retain the transmission matrix while permitting moisture flow between the matrix and the soil.
3. Transmission Matrix: The internal cavity is filled with a transmission matrix designed for effective moisture transfer.
4. Electrode Matrix Chamber: A separate chamber, formed by a slowly dissolving tablet, houses an electrode matrix.
5. Electrode Configuration: The electrode matrix chamber contains a pair of spaced-apart electrodes embedded in the electrode chamber matrix. These electrodes are connected to external electrical leads via a cap structure.
6. Liner Improvement: The liner is described as a layer of thermally bonded fibers arranged in a specific pattern. This design ensures that the liner retains the transmission matrix while allowing moisture to flow to and from the matrix and the soil.
This prior art outlines a functional soil moisture sensor design but has limitations in terms of response time, moisture data accuracy, and overall efficiency. These shortcomings highlight the need for further improvements in the design and functionality of soil moisture sensors.






 
Summary of the Present Invention:
A Soil moisture sensor according to this invention includes a perforated rigid housing resistant to crushing by external loads. Preferably it is made of an electrically conductive metal or metal alloy.
The Housing forms an internal cavity that is filled with a transmission granular mixture which is made by a granular matrix with granular gypsum. The granular matrix is usually silica sand or ceramic. A liner provided an interface between the granular mixture and the soil.
The transmission granular mixture chamber contains a pair of spaced-apart electrodes, both of which are in contact with a transmission granular mixture chamber. The electrodes placed the bottom of the transmission granular mixture and receives moisture from the soil directly.
Moisture from the soil, which comes into contact with the sensor and the liner through the perforations is transferred by the liner to the bottom transmission granular mixture directly. Which in turn transfers the moisture to the bottom transmission granular mixture chamber and through it passes to the electrodes.
According to a feature of this invention the liner is fibrous, and substantially non-absorptive of water, the fiber which is provided with a hydrophilic surface being laid, non-woven, and bonded together to create a structurally reliable interface with passages of various and irregular cross-sections.
The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which:
The present invention provides a novel and advanced soil moisture sensor designed to overcome the limitations of existing technologies. The invention prioritizes improved durability, accuracy, and rapid soil moisture detection, making it highly effective in agriculture, horticulture, and water resource management.
Structural Overview
The soil moisture sensor features a perforated rigid housing, which serves as a protective shell for its internal components. This housing is made of an electrically conductive metal or metal alloy, chosen for its strength, resistance to external loads, and corrosion-resistant properties. The housing is designed to withstand harsh environmental conditions, ensuring long-term functionality.
Internal Cavity Design
Inside the housing is an internal cavity filled with a specially formulated transmission granular mixture. This cavity serves as the primary medium for moisture transmission to the sensor's electrodes. The cavity is lined with a fibrous liner, which acts as a barrier between the soil and the granular mixture, facilitating controlled moisture transfer.
Transmission Medium
A central innovation of this invention is the transmission medium, which comprises:
1. Granular Gypsum:
Granular gypsum is a critical component that enhances moisture transmission. It is chosen for its ability to absorb and evenly distribute water throughout the medium.
2. Granular Composition:
The granular composition, typically made of silica sand or ceramic particles, provides structural support and facilitates the movement of moisture within the internal cavity. Its composition is optimized to prevent clogging and ensure consistent moisture distribution.
This combination of granular gypsum and the particulate composition ensures effective moisture transfer from the soil to the electrodes, minimizing delays and inaccuracies in measurement.
Moisture Transfer Mechanism
The housing is equipped with perforations that allow soil moisture to enter. Moisture passes through the perforations and interacts with the fibrous liner, which directs the moisture into the granular mixture. The moisture flows downward through the mixture and is transferred to the bottom transmission granular mixture chamber, where the electrodes are positioned.
Electrode Arrangement
At the base of the transmission granular mixture chamber, the sensor houses a pair of spaced-apart electrodes. These electrodes are in direct contact with the granular mixture and are responsible for measuring the electrical conductivity, which corresponds to the soil's moisture level. The placement of these electrodes ensures optimal exposure to moisture for precise and reliable readings.
Innovative Liner Properties
The liner, a crucial component, is made of non-woven, thermally bonded fibers with a hydrophilic surface. It is designed to:
• Create structurally reliable interfaces with the granular mixture.
• Facilitate moisture transfer through irregularly shaped passages.
• Prevent water absorption, ensuring efficient transmission of moisture to the granular mixture and, subsequently, to the electrodes.
This advanced liner design reduces response time, eliminates data inconsistencies, and enhances overall sensor performance.
Advantages Over Prior Art
1. Rapid Moisture Detection: The combination of granular gypsum, matrix materials, and a fibrous liner ensures real-time moisture sensing with minimal delays.
2. Durability: The rigid housing and robust liner make the sensor resilient to harsh environmental conditions and physical stresses.
3. Enhanced Accuracy: The design ensures consistent and precise moisture readings, avoiding errors caused by delayed or uneven moisture transmission.
4. Efficient Moisture Flow: The granular mixture and liner work synergistically to maintain smooth and continuous moisture transfer from the soil to the electrodes.
Applications
The sensor is ideal for precision agriculture, where accurate soil moisture data is crucial for optimizing irrigation. It also has potential applications in landscaping, environmental monitoring, and water resource management.
Conclusion
By integrating a perforated rigid housing, a specialized granular mixture, innovative liner technology, and a robust electrode configuration, this invention delivers a significant advancement in soil moisture sensing. It addresses the limitations of existing technologies while offering practical solutions for modern agricultural and environmental needs.





 
Detailed Description of the present embodiments:
The sensor (10) comprises a robust housing (12) made of an electrically conductive metal, designed to withstand external loads. The housing features an interior wall (13) with perforations (15), forming a circular internal cavity (14). This cavity houses the functional components of the sensor.
A liner (16) is fitted against the interior surface of the wall (13), serving as an interface between the surrounding soil (17) and the transmission granular medium (18 and 22), which fills the internal cavity. This granular medium is tightly packed against the liner, ensuring firm contact with the soil. The base of the housing is sealed with a closure (19) to protect the internal components.
The transmission medium consists of a granular mixture of insoluble materials(18), such as silica sand, combined with slowly soluble granular gypsum(22). The granular size is optimized to allow the medium to distend into the perforations, facilitating effective contact with the soil. Moisture from the soil passes through the liner into the transmission medium, enabling accurate measurement of soil moisture content.
For the sensor to operate as a conductivity-based device, the presence of ions in the water is essential. In cases where water has insufficient natural conductivity, the granular gypsum within the transmission medium provides a source of ions. As moisture permeates the medium, gypsum dissolves gradually, ensuring the formation of a conductive ionic solution. This design ensures functionality even when the soil water has minimal ionic content, such as in scenarios resembling distilled water conditions.
The sensor also features a cap (21) secured to the top of the housing, creating an opening that connects to the transmission medium chamber. The bottom chamber of the transmission medium houses two electrodes (23, 24), which are coaxially arranged metal cylinders. Electrode (23) is positioned inside electrode (24) and is in direct contact with the granular medium at the bottom chamber.
Electrical leads (26, 27) are attached to the respective electrodes and extend through the cap (21) for connection to external instrumentation. These leads facilitate the transfer of data collected by the sensor to the desired measurement system.
A gypsum tablet (20) is positioned at the top of the transmission medium chamber, serving as a long-term source of ions. This tablet ensures consistent ionic conductivity during repeated moisture transmissions, prolonging the sensor's operational life.
The liner (16) is made of a hydrophilic material that enhances the passage of water through its openings, reducing resistance to flow. The material's low water absorption and retention characteristics minimize lag time, enabling faster sensor response. This feature prevents delays caused by the liner absorbing water when dry or releasing retained water too slowly as the medium dries.
Overall, this sensor design ensures efficient and accurate soil moisture detection while maintaining durability and reliability over extended periods of use.










 
Brief Description of the Drawings
FIG. 1: Side Cross-Sectional View of the Sensor
The cross-sectional side view of the sensor (10) illustrates the electrically conductive metal housing (12), featuring perforations (15) on the internal wall (13) that form an internal cavity (14). The liner (16) is shown in close contact with the inside surface of the housing wall, establishing a direct interface with the surrounding soil (17). The cavity is filled with a tightly packed transmission medium (18 and 22), comprising silica sand (18) and granular gypsum (22), which facilitates moisture transfer and ion generation.
At the top of the housing, the cap (21) seals the structure, enclosing the transmission medium. A gypsum tablet (20) is positioned at the top of the medium chamber, ensuring a continuous supply of ions during the sensor's operation. This configuration supports the formation of a conductive ionic solution as moisture interacts with the transmission medium, ensuring reliable conductivity measurements, even in water with low natural ionic content.
FIG. 2: Bottom Cross-Sectional View
A cross-sectional view taken along line 2-2 in FIG. 1 highlights the bottom end of the sensor. The closure (19) secures the base of the housing, protecting the internal components. The bottom transmission medium chamber contains a pair of electrodes (23, 24), depicted as coaxial metal cylinders. These electrodes are in contact with the transmission medium and are connected to electrical leads (26, 27), which extend upward through the cap (21). This arrangement allows the sensor to measure moisture conductivity efficiently by using the ionic solution generated within the medium.
The view further emphasizes the tightly packed transmission medium (18 and 22), composed of silica sand and granular gypsum, which ensures effective moisture transfer and maintains consistent ionic conditions for precise measurements.
FIG. 3: Additional Cross-Sectional View
The cross-sectional side view taken along line 3-3 in FIG. 1 provides another perspective of the sensor (10). This view highlights the electrically conductive metal housing (12) and the liner (16), which is closely fitted against the inside surface of the wall. The liner serves as the interface between the soil and the transmission medium, ensuring seamless moisture flow into the cavity for measurement purposes.
These figures collectively demonstrate the structural and functional components of the sensor, showcasing its innovative design for efficient and accurate soil moisture detection.
, Claims:1 A soil moisture sensor for rapid moisture detection, comprising:
• an electrically conductive robust metal housing, said housing having an inner wall that forms a transmission medium cavity, said wall being perforated to allow moisture passage;
• a water-transmissible liner lining the inner wall and covering the perforations;
• a transmission medium filling the cavity defined by the liner, wherein said medium comprises a mixture of granular gypsum and a granular composition, the gypsum being a slowly dissolving material;
• a gypsum buffer tablet positioned at the top of the transmission medium;
• a pair of electrodes positioned in contact with the transmission medium, placed at the bottom of the cavity and spaced apart from each other, with the electrodes being bridged by the transmission medium,wherein this transmission medium enables rapid transmission of the moisture level with accuracy;
• electrical leads extending from each of the electrodes for conducting electrical signals;
wherein the sensor is sealed against the entry of moisture except through the perforations, and moisture from the surrounding soil in contact with the liner passes through the perforations, the liner, and the transmission medium, causing the gypsum to dissolve, thereby forming an electrically conductive path between the electrodes, with the conductivity of the medium between the electrodes being indicative of the soil moisture level contiguous to the sensor.
2 Sensor according to claim 1, wherein the transmission medium is formed by a granular composition comprising a mixture of granular gypsum and a granular matrix.

3 Sensor according to claim 1, wherein the granular matrix of the transmission medium can include any material, including but not limited to ceramic, sand, silica, dolomite, or other similar substances.
4 Sensor according to claim 1, wherein the granular mixture formed by the granular matrix and granular gypsum may be adjusted in ratio to optimize the moisture transmission and sensor performance.

5 Sensor according to claim 1, wherein the granular matrix mixture comprising granular gypsum can be configured to operate with or without a gypsum buffer tablet to enable the sensor to function effectively in either configuration.

6 Sensor according to claim 1, wherein the cap housing the electrodes includes electrical leads that extend from each electrode, with said leads passing either through the interior or exterior of the transmission chamber.

7 Sensor according to claim 1, wherein the granular matrix mixture comprising granular gypsum allows the sensor to be constructed with a single transmission medium chamber which is the enabler for rapid transmission with accuracy, eliminating the need for a separate electrode chamber, as the electrodes are placed directly within the transmission medium chamber.

8 Sensor according to claim 1, wherein the single granular matrix mixture chamber, with embedded electrodes directly inside this chamber, allows moisture to be directly absorbed from the soil without delay, ensures accurate data for the irrigation controlling system, and facilitates efficient automation based on the moisture level.
9 Sensor according to claim 1,Wherein the concealed housing, made of metal or any other suitable material and adaptable in shape to meet design requirements, enhances the longevity and robustness of the sensor while ensuring efficient and accurate data transmission for soil moisture analysis and irrigation automation.

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