Layered Gel Sheet Balancing Skin Adhesion and Electrode Durability
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Solution Overview
Problem
Existing gel materials for bioelectrodes, such as hydrogels, face issues with adhesion to the skin causing hair entanglement and skin damage during removal, and insufficient durability under pressure, especially in applications like electroencephalography.
Innovation Solution
A gel sheet composed of multiple layers with differing rheological properties, where one layer is harder and less adhesive to the skin to prevent damage and the other layer is softer and more adhesive to the electrode, ensuring durability and effective adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a hydrogel is used for electroencephalography electrodes, then adhesion to the skin is improved, but hair entanglement and skin damage occur during removal
Solution Approach 1:
The gel sheet is divided into two distinct layers: a first gel layer (softer, higher adhesion) for skin contact and a second gel layer (harder, lower adhesion) for electrode contact. This segmentation allows each layer to have optimized properties for its specific function, resolving the contradiction between skin adhesion and skin damage.
Solution Approach 2:
Different regions of the gel sheet have different mechanical properties. The first layer has higher softness and adhesion suited for skin contact, while the second layer has lower softness and adhesion suited for electrode contact and easy removal. This local differentiation of properties solves the contradiction.
2Force
If a hydrogel is used for electroencephalography electrodes, then adhesion to the skin is improved, but the gel breaks under the pushing pressure of the electrode convex portion
Solution Approach 1:
The gel sheet is divided into two distinct layers: a first gel layer (softer, higher adhesion) for skin contact and a second gel layer (harder, lower adhesion) for electrode contact. This segmentation allows each layer to have optimized properties for its specific function, resolving the contradiction between skin adhesion and skin damage.
Solution Approach 2:
Different regions of the gel sheet have different mechanical properties. The first layer has higher softness and adhesion suited for skin contact, while the second layer has lower softness and adhesion suited for electrode contact and easy removal. This local differentiation of properties solves the contradiction.
3Force
If a gel material is used to follow the fine irregularities of the skin, then adhesion is improved, but damage is incurred to the skin when peeling off the gel
Solution Approach 1:
The gel sheet is divided into two distinct layers: a first gel layer (softer, higher adhesion) for skin contact and a second gel layer (harder, lower adhesion) for electrode contact. This segmentation allows each layer to have optimized properties for its specific function, resolving the contradiction between skin adhesion and skin damage.
Solution Approach 2:
Instead of making the entire gel sheet soft and highly adhesive (which causes skin damage on removal), the invention inverts the approach by making the skin-contact layer soft for adhesion while the electrode-contact layer is hard for easy, clean removal. The removal characteristics are inverted to prioritize skin safety.
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 layered gel sheet provides enhanced adhesion to electrodes without causing skin damage and entanglement, while maintaining durability and conductivity, suitable for applications like electroencephalography.
Implementation Method 1
a first gel layer 10 in contact with skin and a second gel layer 20 in contact with an electrode element
Data Source
Figure 1
AI summary
The present invention is intended to provide a gel sheet having a formulation providing an adhesive force on the skin side suitable for the skin (i.e., a gel having a low adhesive force and being able to withstand a tip pressure of a terminal and the like), and concurrently having a sufficient adhesive force against an electrode element on the side opposite to the skin side. The present invention is a gel sheet having a laminated structure of a layer A and a layer B, characterized in that the storage elastic modulus of the layer A at 23°C and 10 Hz is 12,000 to 40,000 Pa, and the storage elastic modulus of the layer B at 23°C and 10 Hz is 2,000 to 10,000 Pa.