Capacitive Sensor Element with Integrated Reference Capacitance
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Solution Overview
Problem
Capacitive pressure sensors face interference from environmental influences like temperature and humidity, which affect both measuring and reference capacitances, leading to inaccurate measurements due to parasitic effects, and existing solutions require significant space and production costs for effective compensation.
Innovation Solution
A capacitive sensor element with integrated measuring and reference capacitance, where the membrane acts as both a deflection counter-electrode and a reference counter-electrode, with the reference capacitance being significantly less sensitive to pressure changes, allowing for effective interference compensation without an additional membrane or increased space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate reference capacitance structure is added to compensate for environmental influences, then measurement accuracy is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines the measuring capacitance and reference capacitance into a single capacitive sensor element. The membrane structure serves dual purposes: it forms the measuring capacitance in its deflection area and the reference capacitance in its edge region, eliminating the need for separate reference structures and reducing device complexity while maintaining measurement accuracy
Solution Approach 2:
The membrane is designed to perform multiple functions simultaneously. It acts as both the pressure-sensitive measuring element and the reference element for environmental compensation. This multi-functionality allows a single structure to provide both measurement and compensation functions, reducing the overall device complexity
2Measurement precision
If a separate reference capacitance structure is added to compensate for environmental influences, then measurement accuracy is improved, but manufacturing costs increase
Solution Approach 1:
The patent merges the measuring and reference capacitances into a single integrated structure, reducing the number of components that need to be manufactured and assembled. This integration simplifies the manufacturing process and reduces production costs while maintaining the ability to compensate for environmental influences
3Measurement precision
If the membrane is made fully deflectable to improve pressure sensing, then pressure sensitivity is improved, but parasitic capacitance effects increase
Solution Approach 1:
The patent segments the membrane into functionally distinct regions: a deflection area that is fully flexible for pressure sensing and an edge region that provides the reference capacitance. This segmentation allows the membrane to exhibit both high pressure sensitivity in the deflection area and stable reference characteristics in the edge region, reducing parasitic capacitance effects
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
This design enables precise compensation of environmental influences on the measuring capacitance while reducing manufacturing costs and space requirements, improving measurement accuracy and efficiency.
Implementation Method 1
a membrane is subjected to pressure, causing elastic deformation or deflection. This elastic deformation is then detected capacitively by electrically contacting the membrane
Implementation Method 2
When the membrane deforms, the distance between the capacitor electrodes of the parallel-plate capacitor changes, thus altering the capacitance value of the capacitor
Data Source
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AI summary
The invention relates to a capacitive sensor element comprising a carrier (12), which has a capacitor electrode (14) and a reference electrode (16) electrically isolated therefrom, and furthermore a membrane (18), which can be deflected in some regions and which has a deflection region (18a) that acts as a capacitor counter-electrode and an edge region (18b), wherein the membrane is fastened to a fastening section (20), for example a circumferential fastening section, on the carrier (12), and wherein the capacitor electrode (14) and the capacitor counter-electrode (18a) form the measuring capacitance Cmess. The reference electrode (16) forms the reference capacitance Cref at least with a section of the edge region (18b) of the membrane (18) that acts as as a reference counter-electrode, the capacitance value of which reference capacitance reproduces at least a component of a disturbing influence Cpar acting on the measuring capacitance Cmess.