Temperature Indicator Using Phase-Change Gel

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Solution Overview

Problem

Existing temperature indicators lack cost-effectiveness and accuracy in detecting descending critical temperatures, with limited color range and complexity in setting response temperatures, particularly for visual indication by human operators.

Innovation Solution

A descending temperature indicator using a translucent container filled with temperature-sensitive gel that changes color from green to red when exposed to temperatures below a threshold, utilizing a sol-gel solution of polyethylene oxide and polypropylene oxide with high and low density pigments, allowing for a permanent visual indication through gravity-driven color change.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electronic sensors or liquid crystals are used for temperature indication, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improvetemperature detection accuracyVSAvoiddevice structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs a disposable indicator strip containing temperature-sensitive materials that permanently change color at specific temperatures. This eliminates the need for complex electronic sensors, batteries, or display components, providing accurate temperature indication through simple, inexpensive, single-use strips that can be attached to products or packaging.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention replaces electronic sensing and display systems with chemical/physical materials that directly indicate temperature through color changes. Temperature-sensitive dyes, liquid crystals, or phase-change materials are used to substitute for electronic temperature sensors and display mechanisms, dramatically simplifying the device while maintaining measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If bimetallic components are used for temperature indication, then response speed is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvetemperature response speedVSAvoidbimetallic disk shape accuracy

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The patent utilizes materials whose physical or chemical parameters change at specific temperatures, such as color-changing dyes, liquid crystals, or phase-change materials. These materials are incorporated into indicator strips that can be manufactured using standard printing or lamination processes, avoiding the need for precision-bent bimetallic components while achieving rapid temperature response through material property changes.

Inventive Principle:

Principle #35Parameter changes

3Illumination intensity

If leuco dyes are used for temperature indication, then color range is improved, but temperature setting accuracy deteriorates

Engineering Contradiction:

Improvecolor visibility rangeVSAvoidtemperature threshold accuracy

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent employs composite indicator systems that combine multiple temperature-sensitive materials with different transition temperatures and color changes. By layering or mixing materials such as leuco dyes, liquid crystals, and phase-change materials, the indicator can provide both a wide visible color range for easy detection and precise temperature thresholds through the specific transition points of the constituent materials.

Inventive Principle:

Principle #40Composite materials

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

Provides a cost-effective, accurate, and easily recognizable visual indication of temperature excursion, ensuring the gel's water-based composition maintains response accuracy and shelf life with minimal water loss, and the use of specific films ensures the indicator's reliability and durability.

Implementation Method 1

The gel in the container will convert to liquid when it is exposed to temperatures below a set threshold

Methodology Applied

Scientific EffectGel to liquid phase transition: Phase Change

Implementation Method 2

When cooled, the gels convert to liquid and the green, being heavier, will fall due to gravity. The red liquid will then take over the window.

Methodology Applied

Scientific EffectGravity-driven separation: Gravitation

Data Source

PatentUS8562208B2Critical temperature indicator

Publication Date: 2013.10.22 AMERICAN THERMAL INSTR LLC

AI summary

A temperature descending indicator which gives a visual indication when the indicator has been exposed to temperatures below a set threshold temperature includes a container having a translucent portion, a first temperature sensitive gel of a first color which will convert to liquid when it is exposed to temperatures below the set threshold temperature, and a second temperature sensitive gel of a second color which will convert to liquid when it is exposed to temperatures below the set threshold temperature, wherein the second temperature sensitive gel is disposed adjacent the translucent portion in a manner to obscure the visibility of the first temperature sensitive gel. A method of making the indicator includes disposing one color gel over the other.