Prosthesis Covering Envelope Composite Material
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Solution Overview
Problem
Existing prosthetic coverings for limbs, particularly articulated prostheses like femoral prostheses, face challenges in being easy to put on, maintaining aesthetic appearance, and allowing full range of motion without deformation or hindrance, as current materials like silicone lack elasticity and form unsightly folds during use.
Innovation Solution
A composite material covering envelope with a reinforcing fabric of textile fibers (20-30 denier) embedded in a polymer matrix, having an elastic elongation rate greater than 200%, and a manufacturing method involving a positive mold, elastomer application, and crosslinking to create a thin, flexible, and skin-texture mimicking covering that can stretch and maintain shape during prosthetic movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If silicone covering stockings are used to reproduce skin appearance, then aesthetic appearance is improved, but elasticity is reduced and movement is hampered
Solution Approach 1:
The patent applies composite materials by combining a polyurethane foam core with a silicone outer layer. The foam provides structural support and elasticity for movement, while the silicone layer provides skin-like aesthetic appearance. This composite structure resolves the contradiction by allowing the aesthetic benefits of silicone without its movement-restricting drawbacks.
Solution Approach 2:
The patent applies local quality by using different materials in different regions of the covering. The inner foam layer provides mechanical properties for movement, while the outer silicone layer provides aesthetic properties where visible. This spatial differentiation of material properties allows simultaneous optimization of both movement and appearance.
2Ease of operation
If fabric covering stockings are used to allow movement, then movement range is improved, but aesthetic appearance deteriorates
Solution Approach 1:
The patent uses a composite structure where the foam core provides movement capability and the silicone outer layer provides aesthetic appearance, eliminating the need for fabric while achieving both movement freedom and skin-like appearance.
3Strength
If thick composite material is used to protect prosthesis, then protection is improved, but flexibility and movement are reduced
Solution Approach 1:
The patent applies local quality by using a thin foam core (several millimeters) rather than thick material. The foam provides adequate structural protection while its cellular structure inherently provides flexibility. The silicone outer layer is applied only where aesthetic appearance is needed, maintaining thinness overall to preserve flexibility.
Solution Approach 2:
The patent uses a thin foam core and thin silicone outer layer rather than thick rigid material. The foam's cellular structure and the silicone's elastomeric properties create a flexible protective shell that moves with the prosthesis, resolving the contradiction between protection and flexibility.
4Shape
If silicone stocking is used to cover prosthesis, then aesthetic appearance is improved, but deformation occurs during repeated flexion
Solution Approach 1:
The patent uses a composite structure where the foam core provides structural stability and resistance to deformation during flexion, while the outer silicone layer maintains aesthetic appearance. The foam's compressible cellular structure absorbs mechanical stress, preventing the silicone layer from deforming permanently.
Solution Approach 2:
The foam core acts as a cushioning layer that absorbs and distributes mechanical stresses before they reach the outer silicone layer. This beforehand cushioning prevents the silicone from undergoing excessive deformation that would lead to permanent damage or unsightly folds during repeated flexion.
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 provides a covering that is easy to apply, maintains its shape and aesthetic appearance, and allows for a wide range of motion without deformation, ensuring the prosthetic movements are unhindered and maintaining a natural skin-like texture and appearance.
Implementation Method 1
applying at least one layer of elastomer to the reinforcing fabric by impregnating the textile fibers of said fabric
Implementation Method 2
crosslinking, the outer surface of said wall being in contact with the surface of said mold
Implementation Method 3
the composite material has an elastic elongation rate greater than or equal to 200%
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The envelope i.e. covering sock (1), has a wall (5) whose inner surface defines a cavity to receive an articulated limb prosthesis i.e. femoral prosthesis (2). The wall having thickness less than 0.5mm is formed by a composite material having elastic elongation rate that is greater than/equal to 200 percent. The material comprises a reinforcement fabric e.g. thin stocking, drowned in a polymer matrix i.e. silicone resin. The fabric is formed by textile fibers whose fineness ranges between 20 deniers and 30 deniers. The wall is formed by applying a silicone elastomer layer on the fabric. The textile fibers are chosen from a group comprising silk, polyamide, elastane and/or cotton. An independent claim is also included for a method for fabricating a limb prosthesis covering envelope.