Shoe Inlay Absorbent Core Sustained Fragrance Release

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Solution Overview

Problem

Unpleasant foot odor and shoe interior smells persist due to bacterial decomposition of sweat, exacerbated by non-breathable synthetic shoe materials, with existing solutions offering short-lasting fragrance relief or artificial scents in disposable insoles.

Innovation Solution

A shoe insert comprising a cover layer, a damping layer with a recess for an absorbent core, and a valve-like hole-shaped recess for refilling with liquid fragrances, allowing for extended fragrance release and user-selectable scents, using a textile fabric absorbent core that stores and slowly releases fragrance oils.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If deodorizing sprays are applied to feet, then foot odor is temporarily masked, but the effect duration is very short requiring frequent reapplication

Engineering Contradiction:
Improveease of applicationVSAvoidduration of fragrance effect
Core Design Contradiction:
Ease of manufactureVSDuration of action of moving object

Solution Approach 1:

The fragrance is pre-loaded into the absorbent core during insole manufacturing, creating a sustained-release system that eliminates frequent reapplication. The absorbent core gradually releases fragrance over days or weeks through controlled diffusion, providing long-lasting odor protection without requiring user intervention.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The absorbent core acts as an intermediary between the fragrance source and the shoe interior environment. It absorbs and stores fragrance liquid, then releases it gradually through capillary action and diffusion, extending the effective duration from minutes (spray) to days or weeks (insole system).

Inventive Principle:
Principle #24Intermediary (Mediator)

2Duration of action of moving object

If fragrances are incorporated into insole materials during manufacturing, then fragrance is provided in the shoes, but the fragrance smells artificial and has very short duration

Engineering Contradiction:
Improveduration of fragrance effectVSAvoidartificial smell quality
Core Design Contradiction:
Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The system uses liquid fragrance capsules containing concentrated fragrance oil, which evaporate slowly through the absorbent core. This changes the delivery parameter from direct application (strong, artificial smell) to controlled evaporation (natural, pleasant aroma), extending duration while improving smell quality.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The absorbent core uses porous material structure to control fragrance release. The porous network allows slow diffusion of fragrance molecules from the liquid capsule through the core matrix, creating a gentle, sustained aroma that avoids artificial intensity while maintaining long duration.

Inventive Principle:
Principle #31Porous materials

3Strength

If synthetic non-breathable materials are used in shoes, then shoe structure is maintained, but moisture is trapped causing increased foot odor

Engineering Contradiction:
Improvestructural integrityVSAvoidfoot odor generation
Core Design Contradiction:
StrengthVSObject-generated harmful factors

Solution Approach 1:

The system converts the harmful trapped moisture into a beneficial delivery mechanism. The moisture that would normally cause odor is instead used as the vehicle to transport fragrance from the absorbent core through the insole to the foot area, where it evaporates to provide odor protection.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The absorbent core acts as an intermediary that captures fragrance liquid and releases it through controlled diffusion. This mediator system decouples the structural function (synthetic material) from the odor protection function (fragrance release), allowing both to coexist without contradiction.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Duration of action of moving object

If disposable scented insoles are used, then fragrance is provided, but the product cannot be reused and creates waste

Engineering Contradiction:
Improveduration of fragrance effectVSAvoidproduct reusability
Core Design Contradiction:
Duration of action of moving objectVSLoss of substance

Solution Approach 1:

The system allows recovery and reuse of the insole after fragrance depletion. The absorbent core can be recharged by replacing the liquid fragrance capsule, extending the product lifecycle from single-use to multiple uses. This reduces waste while maintaining prolonged fragrance duration through refilling rather than replacement.

Inventive Principle:
Principle #34Discarding and recovering

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 sustained fragrance release for several days or weeks, effectively masking unpleasant odors and improving shoe climate, while being machine washable and reusable, with antibacterial and moisture-absorbing properties to reduce odor formation.

Implementation Method 1

an absorbent core (4) for receiving a liquid fragrance (8)

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

The fragrance penetrates the core and its fabric, particularly the textile fabric, where it is securely stored and trapped

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Implementation Method 3

The fragrance, released from the core, especially through the perforated opening, is then released into the surrounding shoe interior as a gas

Methodology Applied
Scientific EffectEvaporation: Evaporation

Implementation Method 4

the top layer (2) is arranged over and covers the cushioning layer (3) and the absorbent core (4)

Methodology Applied
Scientific EffectPhysical containment: Physical Containment

Data Source

PatentEP3934468B1Shoe inlay and system consisting of a left and a right shoe inlay, and at least one fragrance container
Publication Date: 2023.09.27 WITTGENSTEIN VENTURES GMBH
  • EP3934468B1 patent drawingFigure 1
  • EP3934468B1 patent drawingFigure 2
  • EP3934468B1 patent drawingFigure 3~4

AI summary

The invention relates to a shoe inlay which comprises a cover layer, a cushioning layer and an absorbent core for receiving a liquid fragrance, the cushioning layer having a recess on its upper side for receiving the absorbent core, wherein the cover layer is arranged over and covers the cushioning layer and the absorbent core, wherein the layers are interconnected, and wherein a hole-shaped recess is formed in the cover layer in the region of the absorbent core for loading the absorbent core with liquid fragrances.