Passive RFID Temperature Indicator with Irreversible Thermal Switching
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Solution Overview
Problem
Existing temperature monitoring systems for sensitive objects during manufacturing, storage, or transit lack efficient and power-independent methods to indicate exposure to critical temperature thresholds, and they do not provide irreversible evidence of such exposure.
Innovation Solution
A temperature indicator with a housing, switch circuitry, and a passive RFID module that changes state upon exceeding a threshold temperature, allowing the RFID module to output different values based on the switch circuit condition, providing visual or electronic indications without requiring internal power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a temperature monitoring system uses internal power sources (batteries), then it can continuously monitor and indicate temperature conditions, but it increases device complexity and requires maintenance of power sources
Solution Approach 1:
The patent extracts and removes the power source (battery) from the temperature indicator system. The indicator is designed to be passive, drawing no internal power, and instead uses external power sources or energy harvesting mechanisms to activate only when needed, thereby simplifying the device structure while maintaining monitoring reliability
Solution Approach 2:
The temperature indicator employs self-service mechanisms through passive design where the system monitors temperature conditions without requiring active power management. The indicator automatically activates or changes state based on temperature thresholds being exceeded, eliminating the need for complex power source management and maintenance
2Productivity
If a temperature indicator provides reversible indication, then it can be reset and reused, but it does not provide permanent evidence of temperature exposure
Solution Approach 1:
The patent implements preliminary action by designing the indicator to permanently record temperature exposure events. Once a temperature threshold is exceeded, the indicator undergoes an irreversible change that permanently preserves the information about the temperature event, ensuring that historical data is not lost
Solution Approach 2:
The temperature indicator utilizes color changes or visual state changes that are irreversible once activated. This allows the indicator to provide permanent visual evidence of temperature exposure, where the changed state cannot be reverted, thereby preserving the temperature history information
3Duration of action of moving object
If existing temperature systems require power sources, then they can provide continuous monitoring, but they are not suitable for applications where power availability is limited
Solution Approach 1:
The patent extracts the internal power source requirement entirely from the system design. The temperature indicator is configured to operate without batteries or internal power sources, using passive detection methods that only require minimal energy for state changes or visual indication, enabling indefinite deployment in power-limited environments
Solution Approach 2:
The system employs parameter changes in the physical state of materials (such as phase changes or dimensional changes) that occur passively in response to temperature variations. These parameter changes provide the monitoring function without requiring active energy consumption, allowing the system to operate indefinitely without power sources
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
Enables reliable, power-independent temperature monitoring and irreversible indication of exposure to critical temperatures, facilitating quality control by detecting and recording temperature events without batteries, suitable for various attachment methods and electronic integration.
Implementation Method 1
the second element changes in a size thereof to cause movement of the first element from the first position to the second position in response to the indicator being subjected to a particular temperature
Data Source
AI summary
A temperature indicator includes a first element, a second element, and circuitry configured to detect whether the first element is in an open circuit condition or a closed circuit condition relative to a contact. Responsive to the indicator being subjected to a temperature exceeding a threshold, the second element changes in a size thereof to cause a change in engagement between the first element and the contact. The circuitry is configured to output a value based on whether the first element and the contact are in the open circuit condition or the closed circuit condition.