Multi-diaphragm Capacitive Pressure Sensor for Wide Range
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Solution Overview
Problem
Capacitive pressure sensors have limited dynamic operating ranges, typically no more than four to five decades of pressure, which is insufficient for applications requiring six to seven decades, such as measuring from atmospheric to vacuum pressures, necessitating the use of multiple sensors with different ranges.
Innovation Solution
A pressure sensor design featuring at least two diaphragms with different geometries, such as varying surface areas and wall thicknesses, subjected to a common reference vacuum within a housing, allowing for a wide dynamic measurement range of six to seven decades by utilizing a single sensor with a fluid space between the diaphragms and separate measuring electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single capacitive pressure sensor is used, then the device complexity is reduced, but the measurement precision is limited to a maximum of four to five decades of pressure range
Solution Approach 1:
The pressure sensor is segmented into multiple diaphragms (at least two diaphragms with different geometries and/or wall thicknesses) that are simultaneously subjected to the same measuring pressure. Each diaphragm forms a separate capacitor with its measuring electrode, creating multiple measurement channels within a single sensor device. This segmentation allows the sensor to cover a broader pressure range by utilizing the different mechanical responses of each diaphragm to pressure changes.
Solution Approach 2:
The patent extends the measurement capability from a single pressure range to multiple pressure ranges (six to seven decades) by adding another dimension to the sensor design - multiple diaphragms with different geometries and properties. This dimensional extension in the sensor structure enables simultaneous measurement across a vastly expanded dynamic range without requiring multiple separate sensor devices.
2Measurement precision
If multiple separate pressure transducers are installed to cover six to seven decades of pressure range, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
Multiple pressure sensing functions are merged into a single integrated sensor device. At least two diaphragms with different geometries and/or wall thicknesses are combined within one housing, each forming a capacitor with its measuring electrode. This merging eliminates the need for multiple separate pressure transducers while maintaining the capability to measure across six to seven decades of pressure range, thereby reducing device complexity.
Solution Approach 2:
The single pressure sensor is designed with multi-functionality to perform measurements across a broad spectrum of pressure ranges (from atmospheric pressure of 10³ hPa to vacuum pressure of 10⁻⁴ hPa). The universal design incorporates multiple diaphragms with different properties, allowing the same sensor device to accurately measure both low and high pressures that would traditionally require different specialized sensors.
3Adaptability or versatility
If diaphragms with different geometries and wall thicknesses are used, then the adaptability is improved for wide pressure range measurement, but the manufacturing precision requirements increase
Solution Approach 1:
Different diaphragms within the sensor have locally optimized qualities - different geometries and wall thicknesses tailored to specific pressure ranges. This local quality differentiation allows each diaphragm to be optimally suited for detecting pressure changes in its specific range, enhancing the overall adaptability of the sensor for wide pressure range measurement while managing manufacturing precision requirements through specialized design of each component.
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 reproducible and stable pressure measurements across a very large operating range, effectively addressing the limitations of existing sensors by allowing a single sensor to cover the required range without the need for multiple sensors.
Implementation Method 1
A first measuring electrode is arranged opposite the first diaphragm, the first diaphragm and the first measuring electrode forming a first capacitor having a first capacitance that varies with a change in position of the first diaphragm
Implementation Method 2
A second measuring electrode is arranged opposite the second diaphragm, the second diaphragm and the second measuring electrode forming a second capacitor having a second capacitance that varies with a change in position of the second diaphragm
Implementation Method 3
The reference vacuum may be maintained at a stable level by attaching a getter
Data Source
AI summary
The disclosure relates to a pressure sensor for measuring a fluid pressure, in particular a vacuum pressure. The pressure sensor contains a first and a second diaphragm connected to one another such that they enclose and hermetically seal a fluid space. Fluid can enter and exit the fluid space through a fluid supply element, which is connected to an exterior opening of the sensor. Each of the diaphragms is proximal to a reference electrode and forms a variable capacitor, the capacitance of which depends on the position of the diaphragms, which in turn depends on the pressure in the fluid space.