Multilevel Pressure Sensor Merging Capacitive and Resistive Transducers
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Solution Overview
Problem
Capacitive pressure sensors face limitations in measuring high pressures due to potential destruction and reduced dC/dp dynamics, and struggle with precision in low-pressure vacuum processes, as increasing the distance between components or using stiffer diaphragms compromises measurement accuracy.
Innovation Solution
A pressure sensor design incorporating a capacitive transducer and a resistive transducer, where the capacitive transducer uses a resistive layer to modify pressure-dependent deformation into an electrical signal above a pressure limit value, allowing for accurate measurement through a combination of capacitive and resistive signals across varying pressure ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the distance between the measuring diaphragm and the mating body is increased to enable high pressure measurement, then the measuring diaphragm can rest on the mating body at higher pressures, but the dC/dp dynamics decrease and the sensor becomes more susceptible to destruction
Solution Approach 1:
The patent combines a capacitive transducer and a resistive transducer into a single pressure sensor device. The capacitive transducer measures pressure with high precision in the normal range, while the resistive transducer activates when the measuring diaphragm contacts the mating body at high pressures, providing continued measurement capability without requiring increased electrode distance that would degrade dC/dp dynamics.
Solution Approach 2:
The resistive transducer acts as an intermediary mechanism that takes over the measurement function when the capacitive transducer reaches its limitation. When the measuring diaphragm contacts the mating body, the resistive transducer detects the contact surface area and provides the measurement signal, bridging the gap between normal pressure measurement and high pressure measurement.
2Strength
If stiffer measuring diaphragms are used to enable high pressure measurement, then the diaphragm can withstand higher pressures, but the dC/dp dynamics are lost
Solution Approach 1:
The patent merges two different sensing mechanisms: the capacitive transducer that utilizes the flexibility and dC/dp dynamics of a compliant diaphragm for precise low-to-mid pressure measurement, and the resistive transducer that detects high pressure through diaphragm contact with the mating body. This allows the use of a compliant diaphragm that maintains good dC/dp dynamics while still enabling high pressure measurement through the resistive backup mechanism.
3Reliability
If the measuring diaphragm is supported by an additional overload pressure range to prevent fracture, then the sensor is protected against destruction, but capacitive pressure measurement in a high pressure range becomes impossible
Solution Approach 1:
The patent combines capacitive and resistive sensing capabilities in one device. The capacitive transducer provides precise measurement up to the overload pressure range, while the resistive transducer activates when the diaphragm contacts the mating body at pressures above the overload range. This allows the sensor to maintain protection against fracture while extending measurement capability into the high pressure range through the resistive mechanism.
Solution Approach 2:
The resistive transducer serves as an intermediary that enables high pressure measurement without compromising the protective function of the overload pressure range. When the diaphragm contacts the mating body, the resistive transducer detects the contact and provides measurement data, allowing the sensor to operate safely within the protected range while measuring higher pressures when needed.
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 reliable pressure measurement across a wide range, including high pressures and low vacuum conditions, by stabilizing signals and maintaining dC/dp dynamics, preventing sensor destruction and improving precision in critical transition areas.
Implementation Method 1
The pressure sensor has a capacitive transducer having at least one mating body electrode and at least one diaphragm electrode, wherein the capacity between the mating body electrode and the diaphragm electrode depends on the pressure-dependent deformation of the measuring diaphragm
Implementation Method 2
the pressure sensor furthermore has a resistive transducer to modify a pressure-dependent deformation of the measuring diaphragm into an electrical signal above the pressure limit value based on an electrical resistor that depends on the contact surface area of the measuring diaphragm on the mating body
Data Source
AI summary
A pressure sensor comprises a deformable measuring diaphragm, and a mating body connected in a pressure-tight manner and forms a measuring chamber in which a reference pressure is present. A pressure can be applied to an outside of the measuring diaphragm. The pressure sensor has a capacitive transducer having at least one mating body electrode and at least one diaphragm electrode. Above a pressure limit value for the pressure, at least one central surface section of the measuring diaphragm rests against the mating body with a contact surface area, the size of which is dependent on the pressure. The pressure sensor also has a resistive transducer for converting a pressure-dependent deformation of the measuring diaphragm, when pressed in a range of values above the pressure limit value, into an electrical signal using an electrical resistance which is dependent on the contact surface area of the measuring diaphragm on the mating body.