Reversible Thermochromic Material for Temperature Deviation Tracking
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Solution Overview
Problem
Current temperature sensing materials fail to provide a simple method for initializing color change and accurately tracking time and temperature deviations, especially due to random crystallization processes that lead to inaccurate time estimation and irreversibility issues.
Innovation Solution
A temperature sensing material is developed with a structure that disperses temperature indicating materials with controlled average particle sizes and volume fractions, utilizing a leuco dye, color developer, and color eraser to achieve continuous color density changes with time at predetermined temperatures, ensuring reproducibility and reversibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature indicator changes color by crystallization, then the color change is irreversible under ambient temperature, but the structure becomes complicated and the price increases
Solution Approach 1:
The patent changes the physical state parameter of the temperature indicating material from solid crystalline form to liquid amorphous form, enabling reversible color changes. The material transitions between these states in response to temperature variations, allowing the indicator to reset and be reused without structural complexity.
Solution Approach 2:
The invention utilizes phase transition between crystalline and amorphous states of the temperature indicating material to achieve reversible color changes. This phase transition mechanism allows the indicator to cycle between colored and decolorized states based on temperature conditions, eliminating the need for complex irreversible structures.
2Ease of manufacture
If a temperature indicator is used for individual product management, then the price and size are reduced, but the recording accuracy is insufficient
Solution Approach 1:
The patent employs color changes of the temperature indicating material to provide visual information about temperature conditions. The color intensity and changes correspond to temperature deviations, enabling individual product management with simple, low-cost indicators that maintain adequate measurement precision for their intended use.
3Reliability
If crystallization occurs at random in accordance with crystal nucleation frequency, then the color change is irreversible, but the reproducibility of color change deteriorates
Solution Approach 1:
The patent changes the state parameter from fixed crystalline structure to flexible amorphous liquid state, enabling controlled and reproducible color changes. This parameter change allows the material to respond consistently to temperature variations without random nucleation effects.
Solution Approach 2:
Instead of relying on random crystallization processes, the invention inverts the approach by using amorphous-to-crystalline phase transition that can be controlled and reversed. This inversion of the typical crystallization process provides both irreversibility under ambient conditions and reproducibility through controlled phase changes.
4Ease of manufacture
If a time-temperature indicator uses ink with changing viscosity, then the structure is complicated, but the price is reduced
Solution Approach 1:
The patent uses phase transition of the temperature indicating material itself (between amorphous and crystalline states) to provide time-temperature indication, eliminating the need for separate ink components with changing viscosity. This single-material approach simplifies the structure while maintaining functionality.
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
This solution enables continuous color density changes with time, allowing for accurate estimation of temperature deviation times and improving the reproducibility of color changes, addressing the limitations of existing materials by ensuring consistent and reversible temperature sensing.
Implementation Method 1
a temperature indicating material that changes color by crystallization
Implementation Method 2
the color of the temperature sensing material changes continuously with the lapse of time when the temperature sensing material is at a temperature not lower or higher than a predetermined temperature
Implementation Method 3
PTL 1 discloses a reversible thermochromic microcapsule pigment enclosing a reversible thermochromic composition showing discoloration behavior
Data Source
Figure 1(a)~1(b)
Figure 2(a)~3
Figure 4(a)~5
AI summary
An object of the present invention is to provide a temperature sensing material that changes a color density continuously with the lapse of time at a temperature not lower or higher than a predetermined temperature and a temperature deviation time estimating system using it. In order to achieve the above object, the temperature sensing material according to the present invention is a temperature sensing material having a structure of dispersing a temperature indicating material that changes color by crystallization in a dispersion medium and is characterized in that an average particle size of the temperature indicating material is not larger than a resolution when observed and a volume fraction of the temperature indicating material to the temperature sensing material is not less than 5%.