Pre-Stretched EAP Strap Structure for Controlled Expansion
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Solution Overview
Problem
There is a need for further applications of electro-active polymer (EAP) technology that can maintain a pre-stretched state while allowing expansion in one or two directions, with existing solutions failing to effectively utilize EAPs for varied stiffness in solid bodies.
Innovation Solution
The development of an apparatus comprising composite film layers with a pre-stretched EAP sublayer and a stretchable conductive sublayer, where the conductive sublayer is configured to conform to the EAP sublayer and distribute electrical current, and holders are positioned orthogonally to maintain the EAP in a pre-stretched state, allowing expansion. This apparatus includes a method of mechanically stretching EAPs, applying conductive materials, and using holders to create a skeleton for controlled expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EAP is pre-stretched to maintain stability and reduce variability, then pressure variability on solid bodies is reduced, but the EAP cannot expand to adapt to variable stiffness
Solution Approach 1:
The EAP structure transitions from a static pre-stretched state to a dynamic state where expansion is controlled by electrical activation. The dielectric elastomer can dynamically adjust its dimensions in response to electrical signals, allowing the system to adapt between maintaining stability (pre-stretched state) and providing expansion (activated state) based on operational requirements.
Solution Approach 2:
The patent utilizes electrical voltage as a control parameter to change the physical state of the EAP. By applying voltage, the dielectric elastomer's dimensions change (expansion), while in the absence of voltage, it maintains its pre-stretched configuration. This parameter-based control resolves the contradiction between stability and adaptability.
2Adaptability or versatility
If EAP is allowed to expand freely to accommodate variable stiffness, then adaptability improves, but pressure variability increases and stability is lost
Solution Approach 1:
The system incorporates electrical control that can respond to conditions and regulate EAP expansion. By monitoring and controlling the electrical activation, the system can prevent excessive expansion that would lead to pressure variability, while still allowing necessary expansion for adaptability.
Solution Approach 2:
The EAP structure transitions from a static pre-stretched state to a dynamic state where expansion is controlled by electrical activation. The dielectric elastomer can dynamically adjust its dimensions in response to electrical signals, allowing the system to adapt between maintaining stability (pre-stretched state) and providing expansion (activated state) based on operational requirements.
3Ease of manufacture
If conventional materials are used without pre-stretching, then manufacturing is simpler, but electrical breakdown strength and instability are problematic
Solution Approach 1:
The EAP undergoes pre-stretching during manufacturing as a preliminary action that establishes the desired dimensions and improves electrical breakdown strength. This pre-stretching is performed once during fabrication, after which the material maintains its enhanced properties during use, resolving the contradiction between manufacturing simplicity and reliability.
Solution Approach 2:
The patent utilizes electrical voltage as a control parameter to change the physical state of the EAP. By applying voltage, the dielectric elastomer's dimensions change (expansion), while in the absence of voltage, it maintains its pre-stretched configuration. This parameter-based control resolves the contradiction between stability and adaptability.
4Reliability
If EAP is pre-stretched to improve electrical breakdown strength, then reliability improves, but the device complexity increases due to holders and conductive layers
Solution Approach 1:
The patent employs a composite structure combining dielectric elastomer layers with conductive layers and holder elements. This composite approach integrates multiple functions (structural support, electrical conduction, mechanical constraint) into a unified system, where the complexity is justified by the significant improvement in electrical breakdown strength and overall reliability.
Solution Approach 2:
The holders and conductive layers serve multiple functions: they provide mechanical support, maintain pre-stretch, enable electrical activation, and constrain expansion. By making these components multi-functional, the patent reduces the need for separate dedicated components, thereby managing device complexity while maintaining reliability.
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 solution enables the EAP to maintain a pre-stretched state with controlled expansion, reducing pressure variability on solid bodies of variable stiffness, improving electrical breakdown strength and minimizing instability, while allowing for efficient activation and pressure application.
Implementation Method 1
Electro-active polymers may exhibit a change in size or shape when stimulated by an electric field
Implementation Method 2
a pre-stretched electro-active polymer ('EAP') sublayer
Implementation Method 3
the stretchable conductive sublayer is configured to receive and distribute electrical current through the pre-stretched EAP sublayer
Data Source
AI summary
A structure including an electro-active-polymer (“EAP”). The structure can take the form of a strap, which includes two or more EAP film layers. The structure can further include one or more holders or end-grabbing portions. Methods of making and using the EAP structure are also envisioned.