Thermochromic Temperature Sensor With Color Memory Threshold Indication

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Solution Overview

Problem

Existing temperature-sensitive products lack a reliable and direct method to indicate the exposure to a specific temperature threshold, which can compromise their quality and safety, such as vaccines and food products, the existing temperature-sensitive products lack a reliable method to indicate exposure to a specific temperature threshold, which can affect their quality and safety.

Innovation Solution

A temperature sensor that includes a color-changing system comprising a dye, a developer, and a solvent, where the interaction between the dye and the developer results in a visible color change upon exposure to a preselected temperature threshold, with a color-memory property to retain the color change.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a temperature sensor is designed to provide direct visual indication of temperature threshold exposure, then measurement precision and reliability are improved, but device complexity increases due to the need for multiple chemical components (dye, developer, solvent)

Engineering Contradiction:
Improvetemperature threshold detection accuracyVSAvoidchemical composition complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent utilizes thermochromic color changes in a dye-developer system to provide direct visual indication of temperature threshold exposure. The dye and developer interact at specific temperatures to produce visible color changes, eliminating the need for electronic displays or complex sensing mechanisms while maintaining high measurement precision for temperature threshold detection.

Inventive Principle:
Principle #32Color changes

Solution Approach 2:

The temperature sensor employs a composite chemical system consisting of multiple components (dye, developer, and solvent) that work together to achieve the desired thermochromic effect. This composite material approach allows the sensor to provide reliable temperature indication through the synergistic interaction of its constituent chemicals, resolving the contradiction between measurement precision and device complexity.

Inventive Principle:
Principle #40Composite materials

2Loss of information

If the color-changing system is designed to retain color change for recording thermal history, then loss of information is reduced, but stability of the object's composition deteriorates due to the color-memory property

Engineering Contradiction:
Improvethermal history recording accuracyVSAvoidcolor-changing system stability
Core Design Contradiction:
Loss of informationVSStability of the object's composition

Solution Approach 1:

The patent applies the inversion principle by designing a system where the color change is retained not through inherent stability, but through the formation of a stable colored complex that resists reversing. The dye-developer interaction creates a colored product that maintains its state even when temperature conditions change, effectively recording thermal history while managing composition stability through the stability of the colored complex itself.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The color-memory property is achieved by exploiting parameter changes in the dye-developer system at specific temperature thresholds. The system undergoes a chemical transformation at the threshold temperature that results in a stable colored state, allowing thermal history to be recorded. This parameter change approach resolves the contradiction by using controlled chemical transformation to retain information while managing overall system stability.

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 temperature sensor effectively indicates exposure to a specific temperature threshold, providing a direct visual indication of thermal history, ensuring the quality and safety of temperature-sensitive products.

Implementation Method 1

Upon exposure to a preselected temperature threshold, association or disassociation of the dye and the developer results in a visible color change

Methodology Applied
Scientific EffectThermochromism: Thermochromism

Data Source

PatentEP3945851B1Thermochromic temperature sensor
Publication Date: 2025.12.24 CHROMATIC TECHNOLOGIES INC
  • EP3945851B1 patent drawingFigure 1A~1C
  • EP3945851B1 patent drawingFigure 2A~2B
  • EP3945851B1 patent drawingFigure 2C~2D

AI summary

A temperature sensor, and methods of making and using such a temperature sensor, whereby the temperature sensor includes a reversible thermochromic color-changing system having a dye, a developer, and a solvent. Upon exposure to a preselected temperature threshold, association or disassociation of the dye and the developer results in a visible color change. Further, the color-changing system includes a color-memory property which facilitates retention of the color change to effectively record exposure to the temperature threshold.