Capacitive Pressure Sensor Foam Adhesion
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Solution Overview
Problem
Capacitive pressure sensors with foam sheet elastic body layers often experience insufficient adhesive force between adhesive layers and the elastic body layer, leading to partial peeling of electrode sheets and inaccurate pressure detection.
Innovation Solution
The use of fine air bubbles with an average diameter of 2 to 40 µm on the foam sheet surface prevents adhesive penetration, maintaining the film thickness and ensuring a strong adhesive force, while open cells allow air escape, maintaining sensitivity and preventing rupture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a foam sheet is used as the elastic body layer, then the pressure sensor can detect pressure through elastic deformation, but the adhesive force between the adhesive layer and the foam sheet surface is insufficient due to open air bubbles acting as penetration inlets
Solution Approach 1:
The patent utilizes a foam sheet with controlled porous structure (air bubbles) as the elastic body layer. The key innovation is controlling the size and distribution of these pores to prevent adhesive penetration while maintaining elastic deformation capability. The foam structure provides both the necessary mechanical properties and controlled porosity to solve the adhesion problem.
Solution Approach 2:
The patent changes the physical parameters of the foam sheet, specifically the air bubble diameter (controlling porosity characteristics) and foam density. By adjusting these parameters, the adhesive penetration is prevented while maintaining sufficient adhesive force and elastic deformation properties for pressure detection.
2Strength
If the adhesive layer penetrates into the foam sheet through open air bubbles, then the adhesive can bond to the foam, but the film thickness of the adhesive layer is thinned and adhesive force is reduced
Solution Approach 1:
The controlled porous structure of the foam sheet with specific air bubble size ranges creates a barrier that prevents excessive adhesive penetration. The pore size is engineered to be small enough to restrict adhesive flow while large enough to maintain foam elasticity.
Solution Approach 2:
By changing the physical parameters of the foam (air bubble diameter, density distribution), the patent optimizes the balance between preventing adhesive penetration (maintaining thickness) and allowing sufficient bonding. The parameter optimization ensures the adhesive layer maintains its film thickness while achieving strong adhesion.
3Strength
If fine air bubbles with diameter of 2 to 40 µm are used in the foam sheet, then adhesive penetration is prevented and adhesive force is maintained, but the manufacturing precision required to control bubble size increases
Solution Approach 1:
The patent specifies a particular range for air bubble diameter (2 to 40 µm) that balances adhesive prevention with manufacturing feasibility. This parameter range is optimized to achieve the desired adhesive performance while being attainable through conventional foam manufacturing processes.
Solution Approach 2:
The patent may employ different foam densities or bubble size distributions in different regions of the elastic body layer. The surface region might have smaller bubbles to prevent adhesive penetration, while deeper regions have larger bubbles to maintain overall elasticity and pressure response.
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
This configuration ensures the electrode sheets move integrally with the elastic body layer deformation, allowing accurate pressure detection and maintaining constant sensitivity, with a thermosetting adhesive and silicone resin foam sheet enhancing restorability and temperature stability.
Implementation Method 1
the air bubbles of the foam sheet being the fine air bubbles having the average air bubble diameter of 2 to 40 μm, even when the air bubbles open on the surface of the elastic body layer, the film thickness of the entire adhesive layer is not thinned due to the penetration of the adhesive from the open air bubbles into the elastic body layer
Implementation Method 2
open cells allow air escape, maintaining sensitivity and preventing rupture
Implementation Method 3
the capacitive pressure sensor detects a pressing force based on a capacitance change between the first electrode layer and the second electrode layer according to a distance change between the first electrode layer and the second electrode layer
Implementation Method 4
a thermosetting adhesive and silicone resin foam sheet enhancing restorability and temperature stability
Data Source
Figure 1~2
AI summary
Problem Provided is a capacitive pressure sensor that allows sufficiently obtaining an adhesive force of an adhesive layer with respect to an elastic body layer made of foam sheet. Solution means A capacitive pressure sensor 1 according to the present invention includes a first electrode sheet 2, a second electrode sheet 3, an elastic body layer 4 formed by a foam sheet in which air bubbles 41 having an average air bubble diameter of 2 to 40 µm are dispersed and sandwiched between the first electrode sheet 2 and the second electrode sheet 3, and adhesive layers 5, 5, one adhesive layer being formed on a surface of the elastic body layer 4 on a side of the first electrode sheet 2 and another adhesive layer being formed on a surface of the elastic body layer 4 on a side of the second electrode sheet 3.