Bar Code Time Temperature Indicator Using Photochemical Dye
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Solution Overview
Problem
Current time/temperature indicators for perishable goods are expensive and cannot effectively identify non-compliance with storage requirements, nor can they be easily applied to low-cost items or activate close to the time of packaging, and consumers often overlook them, leading to the sale of unsuitable products.
Innovation Solution
A bar code system where some bars or spaces are colored with dyes that change color in response to acids or bases, activated by energizing radiation, rendering the code unreadable when the product becomes unsafe, thus paralleling the product's deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional time/temperature indicators are used, then temperature monitoring capability is provided, but cost increases significantly
Solution Approach 1:
The patent combines the bar code identification system with the time/temperature indicator function into a single integrated structure. The bar code bars themselves serve as the temperature indicator elements, eliminating the need for separate indicator components and reducing overall system cost while maintaining both identification and temperature monitoring capabilities.
Solution Approach 2:
The bar code structure is designed to serve multiple functions: product identification through standard bar code reading and simultaneous temperature monitoring through the temperature-responsive properties of the bar materials. This multi-functionality eliminates the need for separate dedicated temperature indicator devices, reducing cost.
2Reliability
If conventional time/temperature indicators are used, then temperature monitoring is achieved, but they cannot identify the point of non-compliance with storage requirements
Solution Approach 1:
The patent introduces a temperature-sensitive material as an intermediary between the bar code structure and the reading system. This material changes its optical properties (color, reflectivity, or structural characteristics) in response to temperature variations, enabling the bar code reader to detect temperature history and identify storage non-compliance events through the modified bar code pattern.
Solution Approach 2:
The bar code bars incorporate temperature-sensitive materials that undergo color changes or optical property changes in response to temperature variations. These changes are detectable by bar code readers and provide information about temperature exposure history, enabling identification of storage non-compliance without requiring separate indicator devices.
3Ease of manufacture
If dyes are used in bar code, then cost is reduced and ease of application is improved, but the bar code becomes unreadable over time
Solution Approach 1:
The patent employs dyes or pigments whose optical parameters (color, reflectivity) change in response to temperature variations rather than degrading over time. This temperature-dependent parameter change is reversible or stable, allowing the bar code to remain readable under normal conditions while providing temperature monitoring information, thus maintaining both readability and temperature sensing capability.
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 solution provides a cost-effective, easily applicable time/temperature indicator that activates at the appropriate time, ensuring the bar code becomes unreadable when the product is unsafe, thereby preventing the sale of unsuitable goods.
Implementation Method 1
a neutral compound which, on exposure to energising radiation, forms an acid or a base to initiate a colour change in the dye
Implementation Method 2
a dye which will change colour in the presence of an acid or a base
Data Source
AI summary
By printing a bar code (comprising dark and light regions) or parts of such a bar code with an ink containing a dye, which changes color in the presence of an acid or a base to remove the contrast between the regions of the bar code, and a neutral compound which releases an acid or a base on exposure to energising radiation, a bar code can be produced that becomes unreadable after a pre-determined interval. This can be used as a time/temperature indicator to ensure that products, which might be perishable, associated with such a bar code are not used by the public.