Color-Changing Skin Patch for UV Exposure and Protection Testing

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Solution Overview

Problem

Existing technologies fail to provide real-time recognition of ultraviolet exposure to the skin and effective evaluation of ultraviolet protection cosmetics, making it difficult to recognize damage caused by UV rays until inflammation occurs and complicating the timing for reapplication of protection agents.

Innovation Solution

A skin-attaching sheet with a color-changeable layer containing photochromic compounds that changes color visibly upon UV exposure, allowing real-time detection and evaluation of UV protection performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If photochromic materials are used to detect UV exposure, then real-time detection capability is improved, but the ability to evaluate UV protection performance of cosmetics is insufficient

Engineering Contradiction:
ImproveUV exposure detection capabilityVSAvoidUV protection evaluation capability
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The sheet is designed to perform multiple functions: it detects UV exposure through photochromic material and simultaneously evaluates UV protection performance by comparing the sheet's color change with the skin's color change under UV exposure. This multi-functional design resolves the contradiction by making the same device adaptable to both detection and evaluation purposes.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The sheet acts as an intermediary between UV radiation and the skin, providing a visible color change that mediates the invisible UV exposure. By placing the sheet on the skin, it serves as a mediator that both detects UV exposure and enables evaluation of cosmetic protection effects through controlled comparison.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If color-changing materials are applied to clothes and tents, then UV protection is provided, but real-time skin exposure recognition is not achieved

Engineering Contradiction:
ImproveUV protectionVSAvoidSkin exposure recognition
Core Design Contradiction:
Object-affected harmful factorsVSLoss of information

Solution Approach 1:

Instead of applying photochromic materials directly to skin (which would be impractical), the invention creates a copy or surrogate - a sheet with photochromic material that mimics skin's response to UV. The sheet copies the functional aspect of UV sensitivity without the complications of direct skin application, enabling visible exposure recognition.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The solution separates the UV protection function (provided by cosmetics on skin) from the detection function (provided by the sheet). This segmentation allows each component to specialize: cosmetics protect while the sheet detects and provides visual feedback, resolving the information loss problem.

Inventive Principle:
Principle #1Segmentation

3Reliability

If photochromic compounds are embedded in fibers, then UV sensitivity is improved, but the ability to provide quantitative evaluation of protection performance is insufficient

Engineering Contradiction:
ImproveUV sensitivityVSAvoidProtection performance evaluation accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The invention utilizes color change as a quantitative measurement mechanism. By embedding photochromic compounds in fibers and observing the degree of color change, the system transforms qualitative UV sensitivity into a measurable, evaluable parameter. The color difference between exposed and protected areas provides precise evaluation of cosmetic protection performance.

Inventive Principle:
Principle #32Color 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

Enables real-time detection of UV exposure and effective evaluation of UV protection cosmetics, facilitating timely protective measures and reducing skin damage.

Implementation Method 1

the fiber contains a photochromic compound

Methodology Applied
Scientific EffectPhotochromism: Photochromism

Data Source

PatentEP4227654B1Patch sheet for skin, use of the same, ultraviolet sensing method, and method for evaluating ultraviolet protection performance
Publication Date: 2025.09.03 KAO CORP
  • EP4227654B1 patent drawingFigure 1~2
  • EP4227654B1 patent drawingFigure 3
  • EP4227654B1 patent drawing

AI summary

A skin-attaching sheet (10) of the present invention includes an attaching portion (1) that is used by attaching to skin. The attaching portion (1) includes a color-changeable layer (3) that changes color through exposure to ultraviolet rays. The attaching portion (1) has a color difference ΔE∗ab in an L*a*b* color system between before exposure and 10 seconds after exposure of 5 or more and 300 or less in a standard exposure test in a moist state. A method of using the skin-attaching sheet (10) includes a step of attaching the attaching portion (1) to skin and a step of applying a liquid substance to the skin.