Capacitive Liquid Sensor PCB Structure for Stable Plate Spacing
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Solution Overview
Problem
Existing capacitive sensors for fluid properties measurement are prone to measurement errors due to fluctuating capacitance values caused by changes in the distance between capacitor plates under external forces, particularly in flowing liquids.
Innovation Solution
A sensor device with a circuit board structure comprising rigid and flexible conductor track carrier sections, where the rigid sections are fixed in slot receptacles and connected by flexible sections to maintain a constant distance, minimizing measurement errors and allowing for accurate determination of liquid properties using capacitive measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitive sensor is used to measure liquid properties, then measurement capability is provided, but measurement precision deteriorates due to capacitance fluctuations caused by distance changes between capacitor plates
Solution Approach 1:
The circuit board structure combines rigid and flexible sections to dynamically adapt to external forces while maintaining capacitor plate alignment. The flexible sections allow the structure to deform under pressure without causing permanent misalignment, while the rigid sections maintain the overall geometric relationship and electrical connections, resolving the contradiction between measurement reliability and precision.
Solution Approach 2:
The circuit board incorporates flexible printed circuit board (FPC) sections that can bend and deform to accommodate external forces applied to the sensor housing. These flexible sections maintain electrical continuity while absorbing mechanical stress, preventing transmission of forces that would otherwise cause capacitor plate distance variations and measurement errors.
2Measurement precision
If the circuit board structure is made rigid to maintain capacitor plate distance, then measurement precision improves, but device complexity increases due to mounting requirements
Solution Approach 1:
The circuit board is segmented into rigid and flexible sections, with rigid portions providing structural stability for precise capacitance measurement and flexible portions enabling simplified mounting in the housing cavity. This segmentation allows the sensor to achieve measurement precision without requiring complex rigid mounting structures, as the flexible sections adapt to the housing geometry.
Solution Approach 2:
The circuit board structure serves multiple functions: the rigid sections provide mechanical stability for precise measurement, the flexible sections enable simplified mounting and accommodation of thermal expansion, and the integrated design eliminates the need for separate mounting brackets or complex fastening mechanisms, reducing overall device complexity.
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 ensures precise and reliable detection of impurities in liquids by maintaining consistent capacitance values despite external forces, enabling effective detection of contaminants like water content and other dielectric impurities in flowing fluids.
Implementation Method 1
a capacitive measuring principle
Implementation Method 2
determination of properties of a liquid in which particularly accurate determining is possible
Data Source
AI summary
Aspects of the present disclosure relate to a sensor device and a method for determining properties of a liquid. In one example, a housing having an inner chamber for accommodating a liquid is provided. A circuit board structure is positioned within the inner chamber and has a plurality of rigid circuit board sections, each of which is connected by flexible conductor track carrier sections. The flexible conductor track carrier sections are each arranged between section edges of the rigid circuit board sections. Conductor surfaces are arranged on the rigid circuit board sections. The rigid circuit board sections are arranged parallel to each other and at a distance from each other, so that gaps are formed therebetween. At least one measuring capacitance is formed by the conductor surfaces facing each other across the gaps. The housing has slot receptacles, wherein section edges of the rigid circuit board sections are held in the slot receptacles.