Stress-Distributing Layer for Stretchable Thin-Film Devices
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Solution Overview
Problem
Existing flexible thin-film devices are primarily bendable but not stretchable, limiting their versatility and durability, especially when subjected to tension forces or twisted applications.
Innovation Solution
A flexible thin-film device with a corrugated surface structure and a stress-distribution layer (SDL) on the upper surface of the functional layers, allowing the device to be both bendable and stretchable along multiple axes without requiring the functional layers to be in a neutral plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the functional layers are placed in a neutral plane to minimize tension forces, then the bending strength is improved, but the tensile strength is not improved and manufacturing complexity increases
Solution Approach 1:
The substrate is designed with a corrugated surface structure featuring periodic waves or undulations. This curved geometry allows the thin-film device to stretch and bend without placing the functional layers in a neutral plane, as the corrugations accommodate dimensional changes while keeping functional layers on the surface for simplified manufacturing.
2Strength
If the functional layers are placed in a neutral plane to minimize tension forces, then the bending strength is improved, but the device is not stretchable
Solution Approach 1:
The corrugated surface structure with periodic waves enables the substrate to expand and contract along the direction of the waves while maintaining structural integrity. This allows the device to be stretchable without requiring functional layers to be in a neutral plane.
Solution Approach 2:
The use of a flexible polymer substrate with corrugated surface structure creates a compliant base that can undergo large deformations. The thin-film functional layers are deposited on this flexible surface, allowing the entire device to stretch and bend while maintaining functionality.
3Strength
If a stress-distribution layer is added to prevent functional layers from breaking, then the tensile strength is improved, but the device complexity increases
Solution Approach 1:
A stress-distribution layer made of flexible polymer material is introduced between the substrate and functional layers. This layer has mechanical properties that distribute tensile stresses uniformly, preventing stress concentration that would cause functional layers to break during stretching.
Solution Approach 2:
The device employs a composite structure combining the flexible polymer substrate, stress-distribution layer, and functional layers. Each layer has optimized mechanical properties that work together to provide both stretchability and protection against functional layer failure.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A flexible thin-film device (10) comprising - a flexible polymer substrate (5) comprising a corrugated surface structure (8) comprising a pattern of waves, the waves following one or more curved lines and/or one or more straight lines; - one or more functional layers (7) on the corrugated surface structure (8), the one or more functional layers (7) defining an upper surface (9) opposite to the corrugated surface structure (8); and - a stress-distribution layer (6) comprising a flexible polymer layer on the upper surface (9).