Conductive Foam Heater Layout for Uniform Patient Warming

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Solution Overview

Problem

Existing flexible resistive heaters used in patient warming devices suffer from rigidity issues that impact pressure management systems, and they often create hot spots due to changes in thermal conduction when pressure is applied, requiring high power to maintain uniform temperature.

Innovation Solution

A method involving the application of a CNT or graphene oxide dispersion onto flexible polymeric foam, which penetrates into the foam structure, forming a conductive layer, and is covered with a polymeric film, with electrical leads stitched or attached to ensure flexible and uniform heating.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If heater is placed under foam pressure management system, then pressure management is maintained, but hot spots occur at contact points due to changed thermal conduction

Engineering Contradiction:

Improvepressure managementVSAvoidtemperature uniformity

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

Instead of placing the heater under the foam pad as in conventional designs, the patent inverts the arrangement by positioning the heater on top of the foam pad. This inversion eliminates the hot spot problem caused by compressed foam altering thermal conduction paths, while still allowing the foam to provide pressure distribution and comfort.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The heater is designed with localized heating zones that can be independently controlled. This allows different regions of the heater to operate at different power levels, preventing hot spots at contact points while maintaining adequate warming in other areas, thus achieving uniform temperature distribution across the surface.

Inventive Principle:

Principle #3Local quality

2Speed

If high power is used to achieve target temperature rapidly, then heating speed is improved, but energy consumption increases

Engineering Contradiction:

Improveheating speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The heater incorporates variable power delivery capability, allowing the power consumption to be dynamically adjusted based on the heating stage. High power is applied initially to achieve rapid heating, then reduced to maintain temperature with lower power consumption, optimizing both heating speed and energy efficiency.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operational parameters by adjusting power delivery in different phases. Initial high power delivery rapid heating phase is followed by reduced power maintenance phase, allowing the heater to achieve target temperature quickly while minimizing overall energy consumption through parameter optimization.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If heater is made flexible and conformal, then adaptability to body shapes is improved, but structural integrity and durability decrease

Engineering Contradiction:

ImproveflexibilityVSAvoiddurability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The heater employs a composite structure combining flexible conductive materials with a foam substrate. The conductive heating elements are integrated into the foam matrix, creating a composite material that maintains flexibility and conformability while the foam structure provides mechanical strength and durability to withstand repeated flexing and compression.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The heater utilizes flexible thin film conductive layers that can conform to body shapes and surfaces. These thin film structures are embedded within or attached to the foam pad, providing the necessary flexibility and adaptability while the foam substrate reinforces the overall structural integrity and resistance to mechanical degradation.

Inventive Principle:

Principle #30Flexible shells and thin films

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 flexible and conformal heating with uniform temperature distribution, eliminating hot spots and reducing power consumption, while maintaining pressure management capabilities.

Implementation Method 1

resistively-heatable flexible, foam... a resistively-heatable CNT, graphene, or graphene oxide layer disposed on the exterior and at least partly within the foam

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

resistively-heatable layer... The resistively-heatable layer may comprise a dispersant or an adhesive... The resistively-heatable layer is preferably in electrical contact with electrodes

Methodology Applied

Scientific EffectElectrical resistance: Electrical Resistance

Implementation Method 3

applying a polymeric film over the CNT, graphene, or graphene oxide layer... a polymeric film disposed over the resistively-heatable CNT, graphene, or graphene oxide layer

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Implementation Method 4

flexible, polymeric solid foam... flexible, foam... maintaining pressure management capabilities

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS20250387998A1Flexible Foam Resistive Heaters and Methods of Making Flexible Resistive Heaters

Publication Date: 2025.12.25 BATTELLE MEMORIAL INST

AI summary

Flexible foam resistive heaters prepared with conductive coatings are described. The invention also includes methods of making flexible lead (busbar) connections with low contact resistance for superior uniformity and lower power utilization than conventional technology.