Excess Temperature Indicator Wick Bonding
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Solution Overview
Problem
Existing temperature exposure indicators fail to provide a long-lasting, fade-resistant visual indication of excess temperature exposure, as the color change over time may fade due to dye migration into adhesives or heat-sensitive coatings, leading to potential confusion about the product's safety.
Innovation Solution
The development of an excess-temperature exposure indicator that attaches the wick to the upper layer using a region of fused upper layer material, eliminating the need for adhesives and incorporating a window seal to prevent dye migration, ensuring a strong and enduring color change visible through a viewing window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If adhesive is used to attach the wick to the upper layer, then the wick is securely fixed, but the dye migrates into the adhesive causing color fading over time
Solution Approach 1:
The patent removes the adhesive layer from the system entirely. Instead of using adhesive to attach the wick to the upper layer, the wick is directly heat-sealed to the upper layer, eliminating the source of dye migration and color fading while maintaining secure attachment.
Solution Approach 2:
The patent introduces heat-sealing as an intermediary process between the wick and upper layer. The heat-sealed region acts as a bonding interface that secures the wick without requiring adhesive, thereby preventing dye migration while maintaining attachment strength.
2Measurement precision
If the indicator material is heat-fusible to enable temperature response, then the indicator can detect excess temperature, but the indicator material may migrate into the upper layer causing color fading
Solution Approach 1:
The patent removes the window seal layer that was causing dye migration. By eliminating this layer, the heat-fusible indicator material can respond to temperature changes without migrating into the upper layer, maintaining both temperature detection capability and visual indication reliability.
Solution Approach 2:
The patent creates a localized heat-sealed region at the interface between the wick and upper layer, while leaving the viewing window area open. This local differentiation allows the indicator material to migrate only to the sealed region rather than into the upper layer through the viewing window.
3Strength
If adhesive is used to secure the wick, then the wick remains in place, but the adhesive contamination affects the melting point of the indicator material
Solution Approach 1:
The patent eliminates the adhesive from the system, removing the source of contamination that would affect the melting point of the indicator material. The heat-sealing process provides secure wick attachment without introducing foreign substances that could alter the thermal properties of the indicator.
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 provides a long-lasting, fade-resistant visual indication of excess temperature exposure, ensuring the indicator remains effective for weeks or months, enhancing reliability and predictability by avoiding adhesive contamination and maintaining the integrity of the melting point of the indicator material.
Implementation Method 1
The indicator material is heat-fusible in response to exposure of the indicator to the elevated temperature to provide a wickable liquid indicator
Implementation Method 2
The liquid indicator is transported along the wick
Implementation Method 3
the window seal provides a high strength bond between the wick and the upper layer and prevents migration of the indicator material from the wick into the upper layer
Implementation Method 4
a region of fused upper layer material attaches the wick to the upper layer
Data Source
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AI summary
An excess temperature indicator can provide a visual indication of past exposure of perishable, maturing and other host products to an elevated temperature exceeding a threshold temperature. The indicator can have an upper layer provided with a viewing window and a wick attached to the upper layer. A reservoir of heat- fusible indicator material can be disposed in contact with the wick, to fuse and move along the wick changing the visual appearance of a first portion of the wick viewable through the window, in response to an excess temperature event. Also, the indicator can have a region of fused upper layer material attaching the wick to the upper layer. Optionally, a window seal can extend around the viewing window to prevent migration of the indicator material. The indicator can be employed to monitor vaccines, foods and other products providing an enduring visual signal of exposure to potentially damaging temperature conditions.