Prosthetic Liner Elastomeric Seal Vacuum Retention
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Solution Overview
Problem
Existing prosthetic liners face challenges in maintaining a secure, air-tight seal between the residual limb and the prosthetic socket, particularly during ambulation, and in effectively utilizing vacuum pressure for secure retention without causing a tourniquet effect.
Innovation Solution
A layered liner with a thermoplastic elastomeric layer and a fabric exterior, featuring radially extending or arcuate silicone or thermoplastic gel sealing elements glued to the fabric, which forms an air-tight seal by impregnating the elastomeric material within the fabric, providing high abrasion resistance and maintaining vacuum pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a reinforcement layer is added to the liner sleeve to provide resistance against axial elongation, then the structural strength is improved, but the radial distension capability deteriorates
Solution Approach 1:
The liner is divided into distinct functional layers: an inner elastomeric layer for radial distension and sealing, and an outer reinforcement layer for axial strength. This segmentation allows each layer to perform its specialized function without compromising the other.
Solution Approach 2:
The liner combines elastomeric material with reinforcement layers to create a composite structure that simultaneously provides radial flexibility and axial strength, resolving the contradiction between these two opposing requirements.
2Reliability
If vacuum pressure is applied to secure the liner within the socket, then the retention reliability is improved, but the risk of tourniquet effect increases
Solution Approach 1:
The liner uses a flexible elastomeric material that can conform to the socket interior and distribute vacuum pressure evenly, maintaining secure retention while reducing the risk of localized compression that causes tourniquet effect.
Solution Approach 2:
The liner material properties are optimized to balance vacuum pressure distribution, allowing sufficient retention force while preventing excessive compression on the residual limb.
3Reliability
If the sealing element is made from silicone or thermoplastic gel, then the air-tight sealing capability is improved, but the abrasion resistance deteriorates
Solution Approach 1:
The sealing element combines silicone or thermoplastic gel with fabric reinforcement, creating a composite structure that maintains the air-tight sealing properties of the elastomeric material while adding abrasion resistance through the fabric layer.
Solution Approach 2:
The fabric reinforcement is applied specifically to the sealing element where abrasion resistance is needed, while the elastomeric material remains exposed at the sealing interface to maintain air-tight properties.
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 ensures a durable, air-tight seal that withstands abrasion and maintains vacuum pressure effectively, reducing the risk of a tourniquet effect and providing improved security and comfort for the user.
Implementation Method 1
maintaining vacuum pressure
Implementation Method 2
thermoplastic elastomeric layer
Implementation Method 3
provide a friction-inducing property to the liner itself
Data Source
AI summary
A prosthetic liner for use with a prosthetic socket that has a thermoplastic elastomeric (TPE) layer that is in contact with the amputee's residual limb. The TPE layer is not uniform in thickness but has ridges to extend circumferentially around the TPE layer. A fabric exterior layer covers the outer surface of the TPE layer conforming to the ridges and is used as a substrate to form a mechanical bond to an elastomeric material. Impregnating the elastomeric material within the fabric exterior occurs by applying an uncured material to the fabric exterior layer and onto at least the apex surfaces located within the sealing regions thereby creating an air tight boundary layer when inserted into a socket. When a vacuum is applied the air is evacuated from the volume below the seal layer. An alternative embodiment comprises a silicone or elastomeric liner with at least one non-unitary sealing element made of silicone or other thermoplastic elastomer further comprising a single radially extending, straight or arcuate silicone or a elastomeric engaging member.