Double-Membrane Capacitive Pressure Sensor Design
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Solution Overview
Problem
Traditional capacitive pressure sensors face a trade-off between measuring range and sensitivity, limiting their application range due to structural features that restrict the ability to achieve high sensitivity without sacrificing the measuring range.
Innovation Solution
A double-membrane capacitive pressure sensor design featuring a combination of thick and thin pressure-sensitive membranes with varying thicknesses, where a supporting material is used between the membranes to create a variable-distance principle, allowing for precise measurement of both low and high-pressure differences through capacitors C1 and C2, respectively, and extending the sensor's measuring range without compromising sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single pressure sensitive membrane is used in traditional capacitive pressure sensors, then the structure is simple, but the measuring range and sensitivity are mutually restricted and cannot be simultaneously optimized
Solution Approach 1:
The pressure sensor is segmented into two distinct capacitive measurement systems: a first capacitor with a thin pressure sensitive membrane for high-sensitivity low-pressure measurement, and a second capacitor with a thick pressure sensitive membrane for high-pressure measurement. This segmentation allows each membrane to be optimized for its specific pressure range, resolving the contradiction between sensitivity and measuring range.
Solution Approach 2:
The invention transitions from a single-membrane one-dimensional measurement approach to a dual-membrane multi-dimensional measurement system. By stacking membranes of different thicknesses and configuring multiple capacitors, the system adds a dimensional layer to pressure measurement, enabling simultaneous optimization of sensitivity (thin membrane) and measuring range (thick membrane) that cannot be achieved in a single-dimensional structure.
2Measurement precision
If a thin pressure sensitive membrane is used to achieve high sensitivity, then the sensitivity is improved, but the measuring range is reduced and the membrane is vulnerable to overload damage
Solution Approach 1:
The thick pressure sensitive membrane acts as a protective cushion for the thin pressure sensitive membrane. When high pressure or overload occurs, the thick membrane deforms first and limits the deformation of the thin membrane, preventing damage to the sensitive thin membrane while allowing it to function normally during low-pressure measurement.
Solution Approach 2:
The thick pressure sensitive membrane serves as an intermediary protective element between the external high-pressure environment and the thin pressure sensitive membrane. It mediates the stress transmission, allowing the thin membrane to remain protected during overload conditions while still enabling accurate low-pressure measurement when conditions are normal.
3Adaptability or versatility
If a thick pressure sensitive membrane is used to extend the measuring range, then the measuring range is improved, but the sensitivity is reduced
Solution Approach 1:
Different regions of the sensor system are assigned different membrane qualities: the thin pressure sensitive membrane region is optimized for high sensitivity in low-pressure zones, while the thick pressure sensitive membrane region is optimized for extended measuring range in high-pressure zones. This local quality differentiation allows each membrane to excel at its designated pressure range without compromising the other.
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 solution enhances pressure measuring precision and extends the sensor's range while providing overload protection for the thin membrane during high-pressure measurements, improving reliability and reducing production costs by optimizing chip area and packaging size.
Implementation Method 1
the capacitor C1 capable of measuring the low-pressure difference comprises a bottom electrode plate and a thin pressure sensitive membrane... When a slight pressure difference acts on the sensor, the thin pressures sensitive membrane is stressed to deform, and the capacitance of capacitor C1 decreases accordingly
Implementation Method 2
the capacitor C2 capable of measuring the high-pressure difference comprises a thick pressure sensitive membrane and a top electrode plate... the capacitance of capacitor C2 increases along with the increase of the pressure
Data Source
AI summary
A double-membrane capacitive pressure sensor comprising a glass substrate, wherein a shallow groove is formed in the center of the glass substrate; a shallow groove through-hole is formed in the center of the shallow groove, and the shallow groove through-hole extends from the bottom surface of the shallow groove to the bottom surface of the glass substrate; a capacitor C1 capable of measuring the low-pressure difference and a capacitor C2 capable of measuring the high-pressure difference are arranged above the shallow groove; the capacitor C1 capable of measuring the low-pressure difference comprises a bottom electrode plate and a thin pressure sensitive membrane, and the capacitor C2 capable of measuring the high-pressure difference comprises a thick pressure sensitive membrane and a top electrode plate.