Tapered Soil Sensor Housing with Flexible Capacitive Array
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Solution Overview
Problem
Existing soil sensor housings with constant cylindrical shapes often fail to ensure a gap-free fit in the ground, leading to inaccurate measurements due to wobbling during installation and soil type variability, particularly in clay soils.
Innovation Solution
A sensor array housed in an elongate hollow housing with a continuously tapered outer and inner wall, featuring a flexible carrier sheet with conductive regions and tangs for secure fitting, ensuring even pressure and contact with the soil surface, and multiple capacitive elements for precise moisture and soil characteristic measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant diameter cylindrical housing is used, then the housing structure is simple and easy to manufacture, but gaps occur between the housing and soil during installation causing measurement errors
Solution Approach 1:
The housing diameter is changed from constant to tapered (decreasing from top to bottom), transforming the geometric parameter to achieve better soil contact and eliminate gaps that cause measurement errors
Solution Approach 2:
The housing transitions from a symmetric constant-diameter cylinder to an asymmetric tapered shape, where the diameter varies along the length, creating better adaptation to soil conditions during installation
2Measurement precision
If a tapered housing is used, then gap-free contact with soil is achieved improving measurement accuracy, but the housing structure becomes more complex
Solution Approach 1:
The housing diameter is changed from constant to tapered (decreasing from top to bottom), transforming the geometric parameter to achieve better soil contact and eliminate gaps that cause measurement errors
3Adaptability or versatility
If a flexible sensor element is used, then the sensor can adapt to the inner wall of the housing, but the sensor structure becomes more complex
Solution Approach 1:
A flexible printed circuit board is used as the sensor substrate, allowing it to conform to the inner wall of the tapered housing while maintaining the simplicity of printed circuit fabrication processes
Solution Approach 2:
The flexible sensor element is shaped to match the curved inner surface of the tapered housing, using curvature to achieve adaptation without complex mechanical structures
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The tapered housing design eliminates gaps between the sensor housing and soil, providing consistent and accurate soil moisture and characteristic measurements across varying soil types, enhancing the reliability of soil sensor data.
Implementation Method 1
capacitive sensor structure
Implementation Method 2
moisture/complex dielectric constant sensor
Implementation Method 3
one of the central resistors being a heater
Data Source
Figure 1~3
Figure 4~5
Figure 6~8
AI summary
The field is sensors used in the ground and in particular the provision of a sensor array element for a sensor array useable in housing that has a tapered internal and external shape. The lack of air spaces and gaps, in particular, between the outer surface of the hollow elongate sensor housing and the surrounding ground is substantially avoided when using a tapered housing. A sensor array element is disclosed including a carrier sheet of flexible material formable into a shape which substantially conforms with the shape of the inner wall of said elongate housing. The carrier sheet has electrically conductive regions wherein at least one pair of electrically conductive regions are shaped and located near enough each other to form a capacitive element. The carrier sheet has at least two pairs of electrically conductive regions forming a pair of capacitive elements, and adjacent pairs of capacitive elements have a different diameter. When the carrier sheet is shaped to substantially conform to the inner wall of the elongate housing and the capacitive element connected to a tuned circuit, the capacitive element and tuned circuit are usable to sense at least the moisture content of the environment surrounding the location of the capacitive element located within the elongate housing. The disclosure is also of a sensor and a sensor array incorporating a sensor array element.