Multi-Electrode Fluid Sensor for Accurate Immersion Detection
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Solution Overview
Problem
Capacitive fluid sensors struggle to differentiate between a surface layer of fluid and a volume of fluid, leading to inaccurate immersion detection, which is crucial for fluid presence and type identification in applications like fluid pumps and analyzers.
Innovation Solution
A fluid sensor design featuring a frame with first and second electrodes separated by a gap, and a third electrode positioned between them, along with a fourth electrode, allows for impedance and voltage difference measurements to distinguish between fluid immersion and surface layer presence, enabling accurate fluid detection and type identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a capacitive fluid sensor is used to detect fluid presence, then fluid detection capability is provided, but the sensor cannot differentiate between a surface layer of fluid and a volume of fluid, leading to inaccurate immersion detection
Solution Approach 1:
The sensor is divided into multiple electrodes (first electrode, second electrode, and third electrode) positioned at different locations. The first and second electrodes detect overall fluid presence, while the third electrode specifically detects surface layer fluid. This segmentation allows the sensor to distinguish between surface layer and volume fluid by comparing signals from different electrode positions.
Solution Approach 2:
The third electrode acts as an intermediary element that specifically detects the presence of a surface layer of fluid. By introducing this intermediate detection point between the first and second electrodes, the system can determine whether fluid is merely coating the surface or if the sensor is fully immersed, thereby resolving the ambiguity in immersion detection.
2Productivity
If impedance measurement between first and second electrodes is used to detect fluid, then fluid presence detection is enabled, but false triggers occur when only a surface layer is present
Solution Approach 1:
The system uses feedback from the third electrode to verify the conditions detected by the first and second electrodes. When the first and second electrodes detect fluid presence, the third electrode's signal is checked to confirm whether it is a surface layer or volume fluid. This feedback mechanism prevents false triggers by requiring consistent signals from multiple electrodes before confirming fluid immersion.
Solution Approach 2:
The third electrode serves as an intermediary verification element that validates the detection signals from the first and second electrodes. By introducing this intermediate check, the system can distinguish between false positive signals caused by surface layer fluid and genuine immersion signals, thereby improving detection reliability without sacrificing speed.
3Measurement precision
If a third electrode is added to detect surface layer fluid, then immersion detection accuracy is improved, but device complexity increases
Solution Approach 1:
The third electrode is designed to serve multiple functions: it detects surface layer fluid presence, provides verification for immersion detection, and helps distinguish between surface coating and volume fluid. By making this additional electrode multi-functional, the increase in device complexity is justified by the significant improvement in measurement precision and the ability to perform multiple detection tasks with a single additional component.
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 sensor system effectively determines fluid presence and type, preventing false triggers and improving reliability in fluid management systems by distinguishing between immersion in a volume of fluid and presence of a surface layer, ensuring precise control and analysis.
Implementation Method 1
a measurement system configured to measure an impedance, Z, between the first and second electrodes
Implementation Method 2
to measure a voltage difference, ΔV, between the third electrode and another electrode of the fluid sensor
Data Source
AI summary
A fluid sensor (15) is disclosed. The sensor comprises a frame (21), first and second electrodes (271, 272) supported by the frame and separated by space occupiable by a fluid, and a third electrode (273) lying in a path (29) on the frame between the first and second electrodes.