Conductive Polymer Diaphragm Pressure Sensor with Peripheral Dielectric Support
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Solution Overview
Problem
Existing pressure sensors are limited in their ability to effectively measure pressures across a wide range, often requiring recalibration and are not suitable for harsh environments due to high costs and limited temperature ranges, especially when using metal, ceramic, or silicon diaphragms.
Innovation Solution
A pressure sensor design featuring a diaphragm plate made of electrically conductive material with a dielectric layer along its periphery, allowing for deflection relative to a backing structure, which changes capacitance in response to applied pressure, enabling reliable operation in harsh conditions and varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If metal, ceramic, or silicon diaphragms are used in pressure sensors, then the sensors can operate at low pressures, but they require high packaged sensor cost and provide operation over a limited operating temperature range
Solution Approach 1:
The patent changes the material parameter from traditional metal/ceramic/silicon diaphragms to a conductive polymer composite diaphragm with specific electrical conductivity (10^-6 to 10^2 S/m) and elastic modulus (0.1 to 10 GPa). This material parameter change enables both extended temperature operation (-50°C to 150°C) and reduced manufacturing cost through simpler processing techniques
Solution Approach 2:
The patent employs a composite material structure consisting of conductive polymer matrix combined with particulate or fibrous fillers (such as carbon black, graphite, or metal particles). This composite approach provides the desired electrical conductivity and mechanical properties while enabling cost-effective manufacturing and broad temperature range operation
2Measurement precision
If traditional pressure sensor technologies are used, then they can detect pressure, but they require recalibration after packaging to properly characterize the input response
Solution Approach 1:
The patent replaces traditional mechanical strain gauge systems with an electrical capacitance sensing mechanism. The conductive polymer diaphragm forms a capacitor where pressure-induced thickness changes directly modulate capacitance, eliminating the need for mechanical recalibration and providing inherent electrical signal output that simplifies characterization
Solution Approach 2:
The conductive polymer diaphragm inherently provides both structural support and sensing functionality through its electrical properties. The material's self-contained piezoresistive and capacitive characteristics enable direct pressure-to-signal conversion without requiring external calibration components or procedures
3Reliability
If a dielectric layer is applied over the entire surface of the diaphragm plate, then the diaphragm is supported, but the flexion region cannot deflect properly to detect pressure changes
Solution Approach 1:
The patent applies the dielectric layer selectively only to the peripheral regions of the diaphragm plate, leaving the central flexion region free of dielectric material. This local differentiation allows the peripheral areas to provide structural support and electrical isolation while the central region maintains full deflection capability for pressure sensing
Solution Approach 2:
The patent segments the diaphragm surface into distinct functional zones: a supported peripheral region with dielectric layer for structural stability and electrical isolation, and a free central flexion region without dielectric for maximum deflection. This segmentation resolves the conflict between support and deflection requirements
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 provides a cost-effective, robust pressure sensing system capable of withstanding high pressures and extreme temperatures, with reliable performance across a wide range of pressures and environments, including corrosive media.
Implementation Method 1
A capacitance of the sensor structure can vary as a function of an amount of the deflection of the flexion region
Implementation Method 2
enable deflection of the flexion region relative to the adjacent surface of the backing plate
Data Source
AI summary
A pressure sensor can include a diaphragm plate of an electrically conductive material, the diaphragm plate including substantially planar opposed first and second surfaces. A layer of a dielectric material can be provided at the first surface of the diaphragm plate along a periphery thereof such that a flexion region of the first surface is substantially free of the dielectric material. The dielectric layer can be configured to engage a fixed structure within a housing to support the flexion region as to enable deflection thereof relative to the fixed structure that changes an electrical characteristic of the pressure sensor in response to application of force at the second surface of the diaphragm plate.