Multi-Layer Susceptor Structure for Diffusion-Resistant Temperature Sensing

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Solution Overview

Problem

Existing susceptor arrangements for inductively heating aerosol-forming substrates face issues with material diffusion and aging, particularly when in direct contact with the substrate, which affect their performance and reliability.

Innovation Solution

A multi-layer susceptor arrangement is introduced, comprising a first layer for primary heating, a second layer as a temperature marker, and a third protective layer sandwiched between them, where the second layer is a Ni-Fe-alloy with a Ni content of 65 wt% or less, and the third layer has a thickness of 70% or less of the second layer, enhancing protection against material diffusion and aging while maintaining effective temperature monitoring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a multi-layer susceptor arrangement with direct contact between the second layer and aerosol-forming substrate is used for temperature monitoring, then temperature control precision is improved, but material diffusion and corrosion increase

Engineering Contradiction:

Improvetemperature monitoring precisionVSAvoidsusceptor arrangement reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

A third protective layer is introduced as an intermediary between the second susceptor layer and the aerosol-forming substrate. This protective layer prevents direct contact, thereby stopping material diffusion and corrosion while allowing the temperature monitoring function to continue through the structured design of the multi-layer arrangement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The susceptor arrangement is segmented into three distinct layers with specific functions: the first layer for heating, the second layer for temperature monitoring, and the third layer for protection. This segmentation allows each layer to perform its function optimally without interfering with others, resolving the contradiction between monitoring precision and reliability.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a thicker third protective layer is used to prevent material diffusion, then protection effectiveness is improved, but inductive heating efficiency decreases

Engineering Contradiction:

Improveprotection against material diffusionVSAvoidinductive heating efficiency

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The thickness of the third protective layer is optimized to a specific range (1-10 μm) that balances two competing requirements: it is thick enough to provide effective protection against material diffusion and corrosion, yet thin enough to allow sufficient penetration of the alternating magnetic field for efficient inductive heating. This parameter optimization resolves the contradiction between protection effectiveness and heating efficiency.

Inventive Principle:

Principle #35Parameter changes

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 improves material savings, reduces material diffusion, and enhances temperature monitoring reliability by using a thin protective layer, allowing precise control of the heating process and extending the susceptor arrangement's lifespan.

Implementation Method 1

The device may comprise an induction source for generating an alternating magnetic field used to inductively heat a susceptor arrangement by inducing at least one of eddy currents and hysteresis losses in the material of the susceptor arrangement

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

Methodology Applied

Scientific EffectHysteresis losses: Hysteresis

Implementation Method 4

the second susceptor material is a magnetic (ferro-or ferrimagnetic) material and chosen such as to have a Curie temperature corresponding to a predefined temperature point for heating the substrate. At its Curie temperature, the magnetic permeability of the second susceptor material drops to unity leading to a change of its magnetic properties from ferro-or ferrimagnetic to paramagnetic. The change of the magnetic properties is accompanied by a temporary change of the electrical resistance of the susceptor arrangement

Methodology Applied

Scientific EffectCurie temperature effect: Curie Point (ferromagnetic)

Data Source

PatentUS20260096603A1Multi-layer susceptor arrangement for inductively heating an aerosol-forming substrate

Publication Date: 2026.04.09 PHILIP MORRIS PRODUCTS SA

AI summary

A multi-layer susceptor arrangement for inductively heating an aerosol-forming substrate is provided, the multi-layer susceptor arrangement including: a first layer including a first susceptor material; a second layer including a second susceptor material; and a third layer including a third material, the second layer being sandwiched between the first layer and the third layer, the second susceptor material including a Ni—Fe-alloy having a Ni content of equal to or smaller than 65 wt %, a layer thickness of the third layer being equal to or smaller than 70% of a layer thickness of the second layer, and the layer thickness of the third layer being in a range of between 2 micrometers and 4 micrometers.