Micromechanical Capacitive Pressure Sensor Coupling Element
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Solution Overview
Problem
Micromechanical capacitive pressure sensors exhibit non-linear output signals due to uneven membrane deflection when pressure is applied, leading to inaccurate capacitance measurements.
Innovation Solution
A micromechanical capacitive pressure sensor design where the second electrode is mechanically and electrically connected to the membrane via a coupling element, typically at its geometric center or via ring-shaped elements, ensuring parallel movement and linear signal output, while also serving as a means for electrical contacting, thus maintaining a simple structure and high sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the electrode is integrated in a membrane that deflects under pressure, then the sensitivity of pressure detection is improved, but the linearity of the output signal deteriorates due to non-uniform deflection
Solution Approach 1:
The patent transitions from measuring deflection at a single point (1D) to measuring lateral displacement across the entire electrode area (2D). By detecting the parallel movement of the electrode in the lateral dimension rather than vertical deflection, the system achieves linear output signal while maintaining high sensitivity through the coupling element connection.
2Measurement precision
If the membrane deflects significantly in its center under pressure, then the sensitivity is improved, but the non-linear change in distance across the capacitor area increases
Solution Approach 1:
The coupling element acts as an intermediary that connects the membrane's vertical deflection motion to the electrode's lateral parallel movement. This mediator converts the non-linear center-deflection motion into linear lateral displacement of the entire electrode, maintaining uniform distance change across the capacitor area while preserving sensitivity.
3Measurement precision
If the second electrode is connected to the membrane at its geometric center via a coupling element, then the sensitivity is maximized, but the robustness against sudden pressure fluctuations may be reduced
Solution Approach 1:
The patent divides the single center connection into multiple distributed coupling elements (ring-shaped connections) around the geometric center. This segmentation distributes the mechanical stress and lateral displacement across multiple connection points, enhancing robustness against sudden pressure fluctuations while maintaining high sensitivity through the collective action of all coupling elements.
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 design achieves high sensitivity and linearity in pressure detection, even under sudden pressure fluctuations, with a robust connection and simple structure, enabling accurate capacitance measurement and absolute pressure sensing.
Implementation Method 1
If the membrane is now deflected by the application of pressure, the distance between the two electrodes forming the capacitor plates and thus the capacitance of the capacitor changes
Implementation Method 2
the second electrode is mechanically operatively connected to a membrane and can be displaced essentially parallel to the first electrode by the membrane
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The sensor (10) has an electrode (14) arranged on a substrate. Another electrode (16) is movable relative to the former electrode. The electrodes partially define a hollow space (18). The latter electrode is mechanically connected with a membrane (22) by a coupling element (24) and is movable parallel to the former electrode by the membrane. The coupling element is arranged around a geometrical middle point of the membrane. The hollow space is closed against an environment in a pressure-tight manner, and exhibits a reference pressure. An independent claim is also included for a method for manufacturing a micromechanical capacitive pressure sensor.