Chipless RFID Temperature Threshold Sensor
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Solution Overview
Problem
Current chipless RFID-based temperature sensors primarily focus on detecting absolute temperature changes, whereas applications like the food supply chain require sensors that can detect when a specific temperature threshold is crossed, rather than the absolute temperature value.
Innovation Solution
Development of chipless RFID-based sensors using a temperature-sensitive material, such as an aqueous solution, which alters the electromagnetic signature when a predefined temperature threshold is exceeded, allowing for detection of temperature threshold violations in applications like produce, biological, and chemical storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chipless RFID-based sensors use temperature-sensitive materials to detect absolute temperature changes, then temperature measurement capability is improved, but the ability to detect specific temperature threshold violations deteriorates
Solution Approach 1:
The patent utilizes phase transitions of temperature-sensitive materials (such as wax or phase change materials) that occur at specific threshold temperatures. When the material undergoes phase transition from solid to liquid or vice versa, it causes a detectable change in the electromagnetic signature of the RFID tag, thereby reliably detecting threshold violations rather than continuous temperature changes
Solution Approach 2:
The patent changes the physical state parameter of the temperature-sensitive material at specific threshold temperatures. By selecting materials with phase transition points matching desired threshold temperatures, the system transforms continuous temperature monitoring into discrete threshold detection, where the material's phase change (solid-liquid transition) produces a binary detectable state indicating threshold violation
2Loss of information
If sensors continuously monitor absolute temperature values, then comprehensive temperature data is obtained, but the ability to provide simple threshold violation alerts deteriorates
Solution Approach 1:
The patent extracts only the critical threshold violation information from continuous temperature monitoring by using phase change materials that respond only when specific temperature thresholds are crossed. This extracts the essential alert function from comprehensive temperature data, providing simple binary threshold violation detection without requiring processing of continuous temperature values
Solution Approach 2:
Instead of continuously monitoring temperature and then determining if thresholds are exceeded, the patent inverts the approach by using materials that automatically indicate threshold violations through phase transitions. The system doesn't measure continuous temperature and then calculate threshold compliance; rather, the material's physical state directly indicates whether a threshold has been violated, simplifying the operation to direct observation of material state or electromagnetic signature change
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 sensors effectively detect when a temperature threshold is crossed and retain this information even after the temperature returns to a safe level, providing reliable monitoring across a range of temperatures from 0°C to -21°C, with potential for broader temperature ranges using different solutes and solvents.
Implementation Method 1
the temperature-sensitive superstrate material is an aqueous solution... when a temperature threshold is crossed... the RFID-based sensor reflects a second EMS, wherein the second EMS is detectably distinct from the first EMS
Implementation Method 2
The change in dielectric properties of the temperature-sensitive material gives rise to a corresponding change in radio frequency signature of the tags
Data Source
AI summary
Provided herein are chipless radio-frequency identification (RFID)-based sensors that exhibit an altered electromagnetic signature when sensor-specific temperature threshold is crossed.