Membrane Pressure Sensor Contact Detection for Over-Deflection Protection
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Solution Overview
Problem
Micromechanical pressure sensors face issues with membrane damage and non-linear pressure dependency due to excessive bending, and capacitive sensors risk electrode damage from pressure surges, necessitating adjustments and protection mechanisms.
Innovation Solution
Incorporating contact elements that establish an electrical contact when a specified pressure is reached, allowing for two-stage pressure capture with different dependencies, using spacer elements to control membrane deflection and prevent damage, and employing capacitive evaluation with insulated electrodes to manage pressure ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the membrane is allowed to deflect freely to capture high pressure, then the pressure measurement range is extended, but the membrane may be damaged due to excessive bending
Solution Approach 1:
The contact elements are positioned in advance at a specific distance from the membrane to detect the approach of the membrane to the stop before actual contact occurs. This preliminary detection allows the system to switch evaluation modes proactively, preventing membrane damage while maintaining extended pressure measurement capability.
Solution Approach 2:
The contact elements act as intermediary detection mechanisms between the membrane and the stop. They provide early warning of membrane deflection limits through electrical contact, enabling the evaluation unit to adjust the evaluation mode before the membrane reaches a dangerous deflection state.
2Reliability
If the membrane deflection is limited to prevent damage, then membrane reliability is improved, but the pressure measurement precision is reduced
Solution Approach 1:
The evaluation mode is dynamically switched based on the deflection state of the membrane. In the first evaluation mode (below contact threshold), the system uses standard capacitive evaluation for high precision. In the second evaluation mode (above contact threshold), the system adapts its evaluation strategy to maintain accuracy while respecting the deflection limit, thus preserving both precision and reliability.
Solution Approach 2:
The system changes the evaluation parameters based on the contact element state. When contact elements detect membrane approach to stop, the evaluation unit switches from one evaluation mode to another, adjusting the measurement parameters to maintain precision within the safe deflection range while preventing membrane damage.
3Adaptability or versatility
If contact elements are added to detect membrane deflection, then pressure range detection is improved, but the device complexity increases
Solution Approach 1:
The contact elements serve multiple functions: they detect the approach of the membrane to the stop, enable switching between evaluation modes, and provide protection against membrane damage. This multi-functionality justifies the added structural elements by consolidating detection and protection roles into a single component system.
Solution Approach 2:
The patent replaces complex mechanical deflection measurement systems with a simpler electrical contact detection system. Instead of using mechanical gauges or complex optical systems to measure membrane deflection, the invention uses simple electrical contact elements that close a circuit when the membrane approaches the stop, significantly reducing device complexity while maintaining detection capability.
4Reliability
If the membrane is constrained to prevent over-deflection, then membrane protection is improved, but the pressure signal linearity is degraded
Solution Approach 1:
The contact elements provide feedback to the evaluation unit about the membrane's deflection state. When the contact elements close due to membrane approach to stop, this feedback signal triggers the evaluation unit to switch evaluation modes, creating a feedback loop that protects the membrane while maintaining signal linearity through adaptive evaluation.
Solution Approach 2:
The evaluation system dynamically adapts its processing based on the contact element feedback. Rather than using a fixed linearization approach that would degrade performance, the system dynamically switches between evaluation modes to maintain optimal linearity and accuracy across different pressure ranges while protecting the membrane from over-deflection.
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
Enables detection of two adjacent pressure ranges without gaps, providing higher resolution and robustness, protecting the membrane from damage, and allowing for short-term pressure peak capture without compromising sensor function.
Implementation Method 1
two contact elements are provided which come into contact with each other, in particular via a mechanical contact, on the basis of the first applied pressure being exceeded so that an electric contact is established
Implementation Method 2
This pressure-dependent bending of the membrane can be captured by piezo elements attached to or on the membrane
Implementation Method 3
the movement of the membrane can also be captured by a capacitor arrangement in which a movable electrode is attached to the membrane and a fixed or non-movable counter-electrode is attached to the housing or the carrier of the pressure sensor element. The pressure-dependent sensor signal can be derived from the change in capacitance between the two electrodes
Data Source
AI summary
A micromechanical pressure sensor element as well as a pressure sensing system comprising such a pressure sensor element, with which the pressure sensor element establishes an electrical contact in the event of a specified first pressure being applied. The pressure sensor element has a membrane that can be moved or deflected by an applied pressure. A first cavity into which the membrane can be deflected is provided below the membrane. Two contact elements are provided which come into contact with each other, in particular via a mechanical contact, on the basis of a first applied pressure being exceeded so that an electric contact is established. At least one first contact element, which is directly or indirectly connected to the membrane, and a second contact element, which is directly or indirectly connected to the cavity bottom, are provided.