Flexible Capacitive Pressure Sensor for Curved-Surface Sensing
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Solution Overview
Problem
Existing pressure sensors made of metal, semiconductors, and piezoelectric crystals are rigid, making them difficult to apply to curved surfaces, unable to withstand large deformations, and affecting wearing comfort, with limited measurement range and sensitivity, particularly in flexible human-machine interaction and smart wearable devices.
Innovation Solution
A capacitive pressure sensor design featuring two electrode layers, a flexible polymer dielectric layer with small hollow spheres and conductive filler, and an insulation dielectric layer, enhancing sensitivity through multiple capacitance change mechanisms and flexibility, allowing application on various surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigid pressure sensor is used, then measurement precision and stability are improved, but adaptability to curved surfaces and wearing comfort deteriorate
Solution Approach 1:
The patent employs flexible polymer materials (such as polydimethylsiloxane PDMS, polyurethane PU, or thermoplastic elastomer TPE) as the substrate and dielectric layer, replacing traditional rigid materials. This flexible membrane structure can bend and deform to adapt to curved surfaces while maintaining capacitive sensing functionality, thus resolving the contradiction between measurement precision and adaptability to curved surfaces.
Solution Approach 2:
The patent uses composite material structures combining flexible polymers with conductive fillers (such as carbon black, silver paste, or conductive polymer particles) to create both the mechanical substrate and the capacitive sensing element. This composite approach maintains flexibility for curved surface adaptation while providing the necessary electrical properties for precise measurement.
2Adaptability or versatility
If a flexible pressure sensor is used, then adaptability to curved surfaces is improved, but measurement range and sensitivity deteriorate
Solution Approach 1:
The patent introduces a porous layer with specific porosity (30-70%) and pore size (1-100 μm) that is locally optimized for pressure transmission. This porous structure allows pressure to be effectively transmitted to the capacitive sensing region while maintaining the overall flexibility of the sensor, thus improving measurement range without sacrificing adaptability.
Solution Approach 2:
The patent employs a porous dielectric layer made from porous polymer materials or porous ceramic materials. This porous structure serves multiple functions: it maintains flexibility for curved surface adaptation, enables pressure transmission to the sensing element, and provides mechanical compliance for withstanding large deformations while maintaining sensitivity.
3Measurement precision
If the first dielectric layer thickness is reduced, then sensitivity is improved, but mechanical strength and stability deteriorate
Solution Approach 1:
The patent uses composite dielectric layers combining flexible polymer matrices with conductive filler particles or porous structures. This composite structure allows the dielectric layer to maintain thinness for high sensitivity while the porous framework and conductive network provide mechanical strength and structural stability.
Solution Approach 2:
The patent employs porous dielectric materials with controlled pore structures that provide mechanical reinforcement. The porous framework acts as a skeletal structure that maintains the integrity of thin dielectric layers, preventing collapse while allowing sufficient flexibility for sensing applications.
4Device complexity
If conventional capacitive sensing is used, then simplicity is maintained, but sensitivity and measurement range are limited
Solution Approach 1:
The patent introduces a porous layer with specifically controlled porosity (30-70%) and pore size (1-100 μm) that is locally optimized for pressure transmission. This porous structure allows pressure to be effectively transmitted to the capacitive sensing region while maintaining the overall flexibility of the sensor, thus improving measurement range without sacrificing adaptability.
Solution Approach 2:
The patent employs a porous dielectric layer made from porous polymer materials or porous ceramic materials. This porous structure serves multiple functions: it maintains flexibility for curved surface adaptation, enables pressure transmission to the sensing element, and provides mechanical compliance for withstanding large deformations while maintaining sensitivity.
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 sensor achieves high sensitivity, wide linear range, and large pressure measurement capabilities while being flexible and bendable, suitable for curved surfaces, with a simple and cost-effective manufacturing process suitable for mass production.
Implementation Method 1
Under an action of pressure, compression of the flexible polymer causes a thickness of the first dielectric layer to decrease, and also causes capacitance to increase
Implementation Method 2
under the action of pressure, the small hollow spheres are more likely to undergo compression deformation than the flexible polymer, causing volumes of the small hollow spheres to become small
Implementation Method 3
Under the action of pressure, volume compression of the flexible polymer causes volume compression of the first dielectric layer, which further causes a volume fraction of the conductive filler to increase
Data Source
AI summary
A capacitive pressure sensor is provided and includes two electrode layers (11 and 14), a first dielectric layer (13), and a second dielectric layer (12). The two electrode layers (11 and 14) are respectively disposed on two sides of the first dielectric layer (13). The first dielectric layer (13) includes a flexible polymer (131), a conductive filler (133), and small hollow spheres (132) that have flexible outer walls. The small hollow spheres (132) and the conductive filler (133) are wrapped in the flexible polymer (131), and some small hollow spheres (132) protrude on a surface that is of the first dielectric layer (13) and that faces at least one of the electrode layers (11 and 14). The second dielectric layer (12) is disposed between at least one of the electrode layers (11 and 14) and the first dielectric layer (13).