Compressible Electrode with Elastic Layer for Pressure Sensing
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Solution Overview
Problem
Existing compressible electrodes for capacitive pressure sensors face issues such as increased hardness leading to reduced sensitivity due to conductive fillers, and adhesion problems on soft polymers, particularly on non-flat surfaces.
Innovation Solution
A compressible electrode design comprising a stably deformable polymer layer with deformed portions and a stretchable conductor layer, combined with an elastic material, allowing for thermoformable deformation and improved adhesion, enabling high sensitivity and ease of production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conductive fillers are added to produce an electrically conductive polymer composite, then electrical conductivity is improved, but the hardness of the deformable polymer increases and sensitivity is reduced
Solution Approach 1:
The patent introduces a separate elastic material layer as an intermediary between the non-conductive polymer substrate and the conductive coating. This mediator allows the soft polymer to maintain its sensitivity while the elastic layer provides a suitable surface for conductive coating adhesion, eliminating the need to add conductive fillers to the polymer itself.
Solution Approach 2:
The electrode is segmented into distinct functional layers: a non-conductive polymer layer for sensitivity, a separate elastic material layer for adhesion, and a conductive coating layer for electrical conductivity. This segmentation allows each layer to optimize its specific function without compromising the others.
2Ease of manufacture
If the non-conductive polymer is made soft to ensure sufficient sensitivity, then sensitivity is improved, but adhesion capacity of the conductive coating to the polymer deteriorates
Solution Approach 1:
The elastic material serves as a mediator layer between the soft non-conductive polymer and the conductive coating. It provides a surface with adequate adhesion properties for the conductive coating while allowing the underlying polymer to remain soft and sensitive.
Solution Approach 2:
Different layers are assigned different mechanical properties: the polymer layer is soft for sensitivity, while the elastic material layer has intermediate properties that balance adhesion and flexibility. This local differentiation of material properties resolves the contradiction.
3Strength
If the adhesion process is performed on non-flat surfaces, then adhesion to the deformable polymer is improved, but manufacturing complexity and difficulty increase
Solution Approach 1:
The elastic material layer is applied to the polymer substrate before the conductive coating. This preliminary action creates a uniform adhesion surface that simplifies subsequent coating processes, eliminating the need to perform adhesion processes on complex non-flat surfaces.
Solution Approach 2:
The elastic material layer provides a homogeneous surface for conductive coating deposition, regardless of the underlying polymer's surface topology. This homogenization simplifies the manufacturing process while maintaining adequate adhesion.
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 design achieves high sensitivity and stability with low drift over time, facilitating mass production and integration into capacitive pressure sensors.
Implementation Method 1
A deformation of the stably deformable polymer layer may be achieved by subjecting the stably deformable polymer layer to external conditions causing the deformation. For instance, the deformation may be caused by one or more of heating, applying a pressure or a vacuum on the stably deformable polymer layer.
Implementation Method 2
an elastic material arranged on the first outer surface such that the elastic material fills the at least one indentation of the at least one deformed portion
Implementation Method 3
A basic capacitive pressure sensor consists of two electrodes with a dielectric in between the electrodes. By applying force/pressure on the sensor, either the dielectric, and/or at least one of the electrodes are deformed, resulting in a measurable change of capacitance value of the sensor.
Data Source
AI summary
The present invention provides a compressible electrode comprising a stably deformable polymer layer comprising a first outer surface, a second outer surface and at least one deformed portion formed as at least one indentation in the first outer surface and at least one corresponding protrusion in the second outer surface, and at least one non-deformed portion. The electrode further comprises at least one stretchable conductor layer arranged on or within the stably deformable polymer layer at the deformed portion and/or at the non-deformed portion. Further, the stably deformable polymer layer is stably deformed at the at least one deformed portion. The electrode further comprises an elastic material arranged on the first outer surface such that the elastic material fills the at least one indentation.