Variable-Hardness Insole for Medial Arch Fit and Pressure Dispersion

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Solution Overview

Problem

Existing insoles do not consider the fit to the user's foot sole and dispersion of pressure applied to the foot sole, leading to potential discomfort.

Innovation Solution

An insole design with a main portion and a medial arch portion, each formed of different hardness materials, where the medial arch portion is shaped to match the foot's medial longitudinal arch and covered by a surface layer material, joined using hot-melt, to enhance fit and pressure dispersion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single-material insole is used, then the manufacturing process is simple, but the fit to the user's foot sole and pressure dispersion is insufficient

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidfit to foot sole
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The insole is divided into multiple portions (heel portion, toe portion, and medial arch portion) with different material properties. The medial arch portion uses a harder material while other areas use softer materials, allowing each region to be optimized for its specific function in supporting and cushioning the foot.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different hardness levels are applied to different regions of the insole based on the specific needs of each foot area. The medial arch portion has higher hardness for structural support, while the heel and toe portions have lower hardness for cushioning, creating localized material properties that match anatomical requirements.

Inventive Principle:
Principle #3Local quality

2Device complexity

If a single-material insole is used, then the material selection is simple, but the pressure dispersion to the foot sole is insufficient

Engineering Contradiction:
Improvematerial compositionVSAvoidpressure concentration
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The insole is segmented into regions with different material hardnesses to distribute pressure more effectively. The harder medial arch portion provides structural support to prevent excessive deformation, while softer portions in the heel and toe areas absorb impact forces, collectively improving pressure dispersion across the foot sole.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The insole combines multiple materials with different hardness properties (measured by durometer) into a single functional unit. This composite structure allows the insole to simultaneously provide cushioning in soft areas and structural support in hard areas, achieving comprehensive pressure management that a single material cannot provide.

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If the medial arch portion is made with different hardness material, then the fit to the medial longitudinal arch is improved, but the manufacturing process becomes more complex

Engineering Contradiction:
Improvefit to medial archVSAvoidmanufacturing process
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The medial arch portion is manufactured as a separate component with its own mold, allowing precise control over its shape and material properties. This separate molding process enables the medial arch portion to be perfectly fitted to the medial longitudinal arch while maintaining manufacturing efficiency through specialized tooling.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The medial arch portion uses a specific hardness level (30-50 durometer) that is optimized for supporting the medial longitudinal arch, while other portions of the insole use different hardness levels. This localized material optimization improves anatomical fit without requiring the entire insole to be manufactured with complex multi-material processes.

Inventive Principle:
Principle #3Local quality

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

Improves shoe comfort by adjusting the insole's shape and hardness distribution to better fit the foot sole, reducing discomfort and facilitating even pressure distribution.

Implementation Method 1

the surface layer material and the upper surfaces of the medial arch portion and of the main portion are joined to each other using a hot-melt

Methodology Applied
Scientific EffectHot-melt: Melting

Data Source

PatentEP4623744A1Insole and insole manufacturing method
Publication Date: 2025.10.01 MADRAS INC
  • EP4623744A1 patent drawingFigure 1
  • EP4623744A1 patent drawingFigure 2~3
  • EP4623744A1 patent drawingFigure 4~5

AI summary

Shoe comfort is improved. An insole for a shoe includes a main portion, a covered portion, and a medial arch portion. The main portion is arranged in a manner that the main portion is to face a heel, a medial longitudinal arch portion, and a lateral longitudinal arch portion of a foot sole. The covered portion is formed in an area on a surface of the main portion, the surface being configured to be adjacent to the foot sole, the area being configured to face the medial longitudinal arch portion. The medial arch portion is arranged so as to cover the covered portion. A surface of the medial arch portion to be adjacent to the foot sole is an upper surface, and a surface of the medial arch portion opposite the upper surface is a lower surface. The lower surface of the medial arch portion has a shape that matches the covered portion. The main portion and the medial arch portion are each formed of a material having a different hardness.