Hollow Polymer Micro-Truss Structures for Adjustable Stiffness
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Solution Overview
Problem
Compliant porous materials used in various applications lack adjustability in physical properties such as stiffness and permeability, which can lead to discomfort and complications like bedsores, and are not effectively permeable to air, compromising skin aeration and circulation.
Innovation Solution
A hollow polymer micro-truss structure is fabricated using a sacrificial scaffold of polymer waveguides, which is coated and then etched to create interconnected tubes with adjustable inner and outer fluid volumes, allowing pressure changes to modify mechanical properties and fluid flow resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If continuous contact material is used to provide structural strength and support, then mechanical support is improved, but skin aeration and circulation are compromised leading to bedsores
Solution Approach 1:
The patent employs a porous foam material structure that provides mechanical support while maintaining high porosity to allow air circulation through the material. The interconnected open cells enable gas permeability, preventing skin aeration issues while retaining the necessary structural strength for medical applications like casts and bedding.
Solution Approach 2:
The patent creates regions of varying density and porosity within the foam structure, with higher porosity zones strategically positioned to enhance air flow and reduce pressure points on the skin, while maintaining adequate structural support in other regions.
2Ease of operation
If adjustable stiffness material is used to reduce patient discomfort, then comfort is improved, but material complexity increases
Solution Approach 1:
The patent utilizes materials with adjustable physical parameters including stiffness, porosity, and density that can be modified during fabrication to optimize patient comfort. The foam structure allows tuning of mechanical properties while maintaining a relatively simple single-material system, avoiding the need for complex multi-component assemblies.
3Strength
If traditional foam material is used to provide cushioning and support, then mechanical support is improved, but air permeability is reduced compromising user comfort
Solution Approach 1:
The patent specifically employs open-cell foam structures with high porosity ratios that maintain excellent air permeability while providing adequate cushioning support. The interconnected cellular architecture allows unrestricted air flow through the material, preventing skin aeration problems while retaining mechanical support capabilities.
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 hollow polymer micro-truss structure allows for adjustable stiffness and permeability, enhancing comfort and wound healing by facilitating air circulation and pressure management, suitable for applications like casts, cushions, and deployable structures.
Implementation Method 1
the sacrificial scaffold may then be removed, for example by etching, to leave behind a hollow structure composed of polymer tubes
Implementation Method 2
The tubes may enclose an interior fluid volume, the pressure of which may be changed to change the dimensions and other properties of the hollow polymer micro-truss structure
Data Source
AI summary
An ordered, 3-dimensional, micro-scale, open-cellular truss structure including interconnected hollow polymer tubes. The hollow micro-truss structure separates two fluid volumes which can be independently pressurized or depressurized to control flow, or materials properties, or both. Applications for this invention include deployable structures, inflatable structures, flow control, and vented padding.