Capacitive Pressure Sensor Diaphragm Local Quality Design
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Solution Overview
Problem
Conventional electrostatic capacitive pressure sensors experience zero-point shift due to deposition components from the medium being measured, leading to measurement errors and reduced durability, as the pressure-sensitive diaphragm flexes under internal stresses from adhered substances.
Innovation Solution
The pressure sensor diaphragm is designed with reduced rigidity in the center portion compared to the peripheral edge portion, either through thinner thickness, tapered, stepped, or cavity-shaped structures, or by using materials with lower Young's modulus, to minimize flexure caused by internal stresses from deposited substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a filter is placed on the connecting hole to prevent deposition components from entering the vacuum gauge, then the adhesion of highly linear deposition components is prevented, but it is impossible to completely exclude deposition components through filtering
Solution Approach 1:
The diaphragm is designed with non-uniform thickness, having a thinner central portion and a thicker peripheral portion. This local quality variation allows the diaphragm to accommodate deposition components without significant flexure, as the thinner center area can deform more easily to compensate for deposits while maintaining overall structural integrity and measurement accuracy.
2Measurement precision
If the diaphragm is made thinner to reduce rigidity and minimize flexure from deposited substances, then zero-point shift is reduced, but the mechanical strength and durability of the diaphragm are compromised
Solution Approach 1:
The diaphragm employs non-uniform thickness distribution with the peripheral portion being thicker than the central portion. This design provides enhanced mechanical strength at the edges where structural support is most needed, while the thinner central area minimizes flexure and zero-point shift caused by deposited substances, thus achieving both strength and precision.
Solution Approach 2:
The diaphragm is constructed using composite material structures that combine materials with different mechanical properties. This allows the diaphragm to have regions with different rigidity characteristics, providing both durability and reduced flexure response to deposition components.
3Measurement precision
If the diaphragm rigidity is reduced to minimize flexure from internal stresses, then measurement accuracy is improved, but the response time and sensitivity to pressure changes may be affected
Solution Approach 1:
The non-uniform thickness design allows the central portion to be thinner for reduced flexure and improved accuracy, while the peripheral portion remains thicker to maintain structural integrity. This localized variation in rigidity enables the diaphragm to respond appropriately to pressure changes while minimizing the impact of deposited substances on measurement accuracy.
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 effectively suppresses zero-point shift and measurement errors by reducing the flexure of the diaphragm, enhancing the sensor's durability and accuracy by minimizing the impact of internal stresses from deposited substances.
Implementation Method 1
a pressure sensor chip for detecting an electrostatic capacitance in accordance with the pressure of a medium to be measured
Implementation Method 2
electrostatic capacitive pressure sensor
Implementation Method 3
the deposits adhering to the pressure sensitive diaphragm produce internal stresses, such as compressive stresses or tensile stresses, after adhesion
Implementation Method 4
the pressure-sensitive diaphragm flexes in one direction, producing zero-point shift
Data Source
AI summary
In an electrostatic capacitance pressure sensor provided with a pressure sensor chip of a diaphragm structure for detecting an electrostatic capacitance in accordance with a pressure of a medium to be measured, one face of a sensor diaphragm of the pressure sensor is a pressure introduction chamber side wherein the medium to be measured is introduced, and the other face is a capacitor chamber side wherein a capacitor portion is formed, where, in the sensor diaphragm, the rigidity is lower towards a center portion from a peripheral edge portion that is a boundary of diaphragm securing portions on the capacitor chamber side.