Polymeric Prosthetic Liner Heat Control via Conductive Additives

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Solution Overview

Problem

Prosthetic and orthotic devices, particularly polymeric prosthetic liners and sockets, retain heat due to their non-breathable and minimally thermally conductive materials, leading to discomfort and skin problems for amputees, as they inhibit effective heat transfer and absorption from the residual limb.

Innovation Solution

Incorporating thermally conductive additives, phase change materials, and enhanced fabric designs to increase the thermal conductivity and heat absorption capabilities of prosthetic liners and sockets, such as using encapsulated or unencapsulated phase change materials, fluid-filled pockets, and high thermal conductivity areas within the polymeric materials, along with conductive coatings and fabric modifications, to facilitate better heat transfer and absorption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polymeric materials (silicone, urethane, TPE) are used for prosthetic liners, then comfort and security of suspension are improved, but heat retention increases leading to discomfort and skin problems

Engineering Contradiction:
Improvecomfort and security of suspensionVSAvoidresidual limb temperature
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent combines polymeric materials with thermally conductive additives (metal particles, ceramic particles, carbon fibers) to create a composite material that maintains the comfort and suspension properties of the base polymer while adding thermal conductivity to reduce heat retention. This directly addresses the contradiction by integrating multiple material properties into a single composite solution.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the thermal conductivity parameter of the polymeric material by incorporating various thermally conductive additives. By changing the physical and thermal parameters of the material through additive incorporation, the liner maintains its mechanical comfort properties while improving heat transfer characteristics to reduce residual limb temperature.

Inventive Principle:
Principle #35Parameter changes

2Strength

If fabric is added to cover the exterior of polymeric material, then wear resistance and ease of donning/doffing are improved, but heat retention is further compounded

Engineering Contradiction:
Improvewear resistanceVSAvoidheat retention
Core Design Contradiction:
StrengthVSTemperature

Solution Approach 1:

The patent applies different material properties to different regions of the liner. The exterior fabric layer provides wear resistance and ease of donning, while the interior polymeric layer with thermally conductive additives handles heat management. This local differentiation of material qualities allows each layer to optimize its specific function without compromising the other.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent introduces thermally conductive additives as intermediary elements between the polymeric material and the fabric covering. These additives act as thermal pathways that conduct heat away from the residual limb through the fabric layer, preventing the fabric from merely acting as an insulating barrier while still providing its protective and functional benefits.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If prosthetic socket is formed from rigid impermeable materials (fiberglass, composites, thermoplastics), then structural strength is improved, but heat transfer is inhibited

Engineering Contradiction:
Improvestructural strength of socketVSAvoidheat transfer efficiency
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The patent replaces the reliance on mechanical/rigid socket materials for heat management with a thermally conductive polymeric liner system. The liner acts as an active thermal management component that complements the structural socket, substituting the need for thermally conductive rigid materials with a flexible, conformable polymer-based thermal conduction system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 enhanced thermal conductivity and heat absorption capabilities reduce residual limb temperature, providing greater comfort and reducing perspiration-related issues, as demonstrated by improved thermal conductivity values and patient feedback.

Implementation Method 1

Incorporating thermally conductive additives... to increase the thermal conductivity and heat absorption capabilities of prosthetic liners and sockets

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

using encapsulated or unencapsulated phase change materials... to facilitate better heat transfer and absorption

Methodology Applied
Scientific EffectPhase change: Phase Change

Implementation Method 3

Incorporating thermally conductive additives, phase change materials, and enhanced fabric designs to increase the thermal conductivity and heat absorption capabilities

Methodology Applied
Scientific EffectLatent heat: Latent Heat

Implementation Method 4

fluid-filled pockets... to facilitate better heat transfer and absorption

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3257479B1Polymeric prosthetic liner with heat control capabilities
Publication Date: 2020.04.22 THE OHIO WILLOW WOOD CO INC
  • EP3257479B1 patent drawingFigure 1A~1B
  • EP3257479B1 patent drawingFigure 2
  • EP3257479B1 patent drawingFigure 3

AI summary

Prosthetic liners, prosthetic sockets and prosthetic suspension sleeves, as well as orthotic components, having enhanced thermally conductivity and/or enhanced heat absorption capabilities. Such components may be used in various combinations to create assemblies and systems that are operative to better transfer heat away from and/or absorb heat produced by residual or intact limbs of a user.