Defrost Indicator With Irreversible Refreeze Detection
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Solution Overview
Problem
During transportation, perishable goods like frozen food may defrost and refreeze, causing damage without being easily detectable, as existing methods do not reliably indicate temperature fluctuations.
Innovation Solution
A defrost indicator that changes state visibly, such as color or configuration, when frozen and defrosted, allowing for detection of temperature rises above freezing by using a fluid that expands and cracks an inner container, with the difference in states indicating defrosting and refreezing events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing temperature monitoring methods are used, then transportation of frozen goods can be maintained, but the ability to detect defrosting and refreezing events is insufficient
Solution Approach 1:
The patent employs color-changing materials that transition between different colors based on temperature conditions. The indicator changes color when exposed to freezing temperatures and maintains different color states for frozen versus defrosted conditions, enabling visual detection of temperature abuse events during transportation
Solution Approach 2:
The invention utilizes phase transition properties of certain materials that change their physical state (solid/liquid or crystalline structure) at specific temperatures. These phase transitions create permanent or semi-permanent visual changes that indicate whether the indicator has been exposed to freezing temperatures, providing reliable detection of temperature fluctuations
2Difficulty of detecting and measuring
If a defrost indicator with multiple states is used, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent uses color-changing materials that provide distinct visual states for different temperature histories. The indicator can display multiple colors or color intensities corresponding to different states (frozen, defrosted, refrozen), enabling comprehensive detection capability while maintaining a simple single-component structure
Solution Approach 2:
The defrost indicator is designed to automatically change states based on temperature exposure without requiring external power, control systems, or user intervention. The material self-registers temperature abuse events through intrinsic physical or chemical changes, eliminating the need for complex electronic monitoring systems
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 reliable and visible indication of temperature fluctuations, enabling the detection of defrosting and refreezing events, thus helping to ensure the quality and safety of transported goods.
Implementation Method 1
using a fluid that expands and cracks an inner container
Implementation Method 2
The process of freezing and defrosting the defrost indicator places the defrost indicator into a state that is not completely reversed by refreezing
Data Source
AI summary
A defrost indicator is configured such that the process of freezing and defrosting the defrost indicator places the defrost indicator into a state that is not completely reversed by refreezing, so that one can detect whether the defrost indicator defrosted and refroze or never defrosted by observing its current state. In an embodiment, the defrost indicator is initially placed in a first state before being frozen (e.g., upside down with fluid in an upper chamber). Freezing the defrost indicator places it in a second state (e.g., with the fluid frozen in the upper chamber). Then when the defrost indicator is defrosted, the defrost indicator is placed into a third state that is different than the first state (e.g., right-side-up with liquid fluid in the lower chamber). If the defrost indicator is again frozen, the defrost indicator is placed into a fourth state (e.g., the fluid frozen in the lower chamber).