Segmented Capacitive Level Sensor for Deep Tank Resolution
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Solution Overview
Problem
Existing capacitive level sensors for liquids in tanks face challenges with high measurement resolution, cost-effectiveness, flexibility, and susceptibility to electrical noise and parasitic capacitances, especially when measuring deep liquid levels with high precision.
Innovation Solution
A capacitive level sensor with a flexible, adaptable structure divided into multiple sections, each with interdigitated electrodes of varying widths and lengths, allowing independent capacitance measurements to reduce noise and enhance signal-to-noise ratio, and featuring a scalable design to accommodate complex tank geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a completely digital capacitive sensor with many discrete electrodes is used to achieve high measurement resolution, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The sensor divides the measurement range into multiple detection zones along the electrode length, allowing each zone to independently detect liquid level segments. This segmentation enables high-resolution measurement without requiring a proportional increase in the total number of electrodes throughout the entire measurement range.
Solution Approach 2:
The electrode structure varies locally along its length, with different sections having different widths to create distinct detection zones. This local variation in electrode geometry allows each zone to have optimized detection characteristics for its specific measurement range, achieving high precision without uniform complexity throughout.
2Measurement precision
If interdigitated electrodes with many detection parts are used to achieve high resolution, then measurement precision is improved, but susceptibility to electrical noise and parasitic capacitances increases
Solution Approach 1:
By segmenting the electrode into multiple detection zones with varying widths, the sensor reduces the total electrode surface area compared to a uniform high-resolution electrode. This segmentation maintains measurement precision in each zone while reducing overall parasitic capacitance and electrical noise susceptibility.
Solution Approach 2:
The electrode width parameter varies along the length of the electrode, creating different detection zones with optimized characteristics. This parameter change allows the sensor to achieve high resolution where needed while minimizing electrode surface area and associated parasitic effects in other regions.
3Ease of manufacture
If a fixed sensor structure is used, then manufacturing is simplified, but adaptability to complex tank geometries is reduced
Solution Approach 1:
The sensor structure incorporates flexible elements that allow the electrode to adapt its shape and position according to the tank geometry. This dynamic capability enables the sensor to maintain its detection functionality across various tank shapes and sizes without requiring completely different sensor designs for each application.
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 solution provides high measurement resolution with reduced electrical noise and parasitic capacitance effects, enabling accurate and cost-effective level detection in deep tanks with improved flexibility and robustness against tank geometry complexities.
Implementation Method 1
capacitive sensor for detection of the level of a medium
Implementation Method 2
detections of which are less affected by electrical noise, such as electrical disturbance, and/or faults of measurement, also due to parasitic capacitances
Data Source
AI summary
A capacitive level sensor comprises a control circuit, a supporting structure and a detection structure on the supporting structure. The detection structure comprises a plurality of electrodes, each including a connection part and a plurality of detection parts which extend in a transverse direction relative to a length direction of the sensor, the detection parts of a first electrode being interdigitated with respect to the detection parts of a second electrode. The detection structure includes a plurality of detection sections, which extend in succession in the length direction and include an upper section and one or more underlying lower sections. Each detection section includes respective first and second electrodes, which are electrically insulated from one another and with respect to the first and second electrodes of the other detection sections. The control circuit is prearranged for selectively applying an electrical potential difference between the first and second electrodes of a corresponding detection section, for detecting a value of electrical capacitance therebetween, and deriving therefrom the level of a medium.