Auxetic Medical Implants With Porous Layers for Perfusion Stability
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Solution Overview
Problem
Existing medical devices and implants, such as dialysis tubes and breast implants, face challenges related to mechanical stability, weight, and homeostasis due to the lack of materials with negative Poisson's ratio (NPR) properties.
Innovation Solution
The integration of materials with negative Poisson's ratio (NPR materials) into medical devices and implants, such as multi-layer bodies with solid outer walls and porous inner walls, hydrogel layers, and NPR-PPR composite materials, to enhance deformation properties and perfusion capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials with positive Poisson's ratio are used in medical devices, then structural integrity is maintained, but mechanical stability and resilience are insufficient
Solution Approach 1:
The patent employs composite materials combining positive Poisson's ratio (PPR) and negative Poisson's ratio (NPR) materials in multi-layer structures. The PPR outer layer provides structural integrity while the NPR inner layer enhances mechanical stability and resilience through its auxetic properties, creating a synergistic composite that resolves the contradiction between structural integrity and mechanical performance.
Solution Approach 2:
The patent applies different material properties to different regions of the medical device. The outer layer uses PPR materials for structural integrity where strength is critical, while the inner layer uses NPR materials for mechanical stability and resilience where deformation control is needed. This spatial differentiation of material qualities resolves the contradiction by optimizing each region for its specific functional requirement.
2Reliability
If denser materials are used to improve mechanical stability, then device strength increases, but device weight increases
Solution Approach 1:
The patent utilizes porous NPR materials that maintain mechanical stability through their unique auxetic structure rather than material density. The porous structure reduces weight while the negative Poisson's ratio effect provides enhanced mechanical stability and deformation control, resolving the contradiction between weight and mechanical stability.
Solution Approach 2:
The multi-layer composite structure combines lightweight porous NPR materials with solid PPR materials. The NPR porous layer provides mechanical stability through its structural response to deformation rather than mass, while the solid PPR layer provides structural support, together achieving mechanical stability without excessive weight.
3Reliability
If solid non-porous materials are used for device walls, then structural strength is maintained, but perfusion capability is reduced
Solution Approach 1:
The patent employs porous NPR materials for device walls that require perfusion capability. The porous structure enables fluid transport and exchange while the negative Poisson's ratio properties maintain structural strength and mechanical stability, resolving the contradiction between porosity and structural integrity.
Solution Approach 2:
The multi-layer composite structure places porous NPR materials in contact with biological tissues or fluids where perfusion is needed, while solid PPR materials are positioned where structural strength is critical. This composite arrangement enables both perfusion capability and structural strength in different regions of the same device.
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 use of NPR materials in medical devices and implants results in lighter, more resilient, and mechanically stable devices that provide improved homeostasis and reduced damage to blood and tissues during contact.
Implementation Method 1
the solid outer wall and the porous inner wall are arranged to permit perfusion of a second liquid from between the solid outer wall and the porous inner wall and through the porous inner wall into the interior space
Implementation Method 2
a porous inner wall having a negative Poisson's ratio
Data Source
AI summary
A medical device includes a multi-layer body defining an interior space configured to contain a liquid. The multi-layer body includes a solid outer wall having a positive Poisson's ratio and a porous inner wall having a negative Poisson's ratio. A method of making a multi-layer body includes applying a stimulus to a precursor material to cause the precursor material to form a porous wall having a negative Poisson's ratio, and attaching a solid wall to the porous wall to form the multi-layer body, the solid wall having a positive Poisson's ratio. A suture includes one or more filaments, at least a first filament of the one or more filaments including a negative Poisson's ratio material. A medical device includes a biocompatible hydrogel, and the biocompatible hydrogel includes a composite of a first material having a negative Poisson's ratio and a second material having a positive Poisson's ratio.