Capacitance Temperature Sensor With Delayed Heat Exposure Detection
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Solution Overview
Problem
Commercial products sensitive to temperature changes lack effective indicators to detect prolonged exposure to high temperatures, which can compromise their efficacy or quality.
Innovation Solution
A capacitance-based temperature indicator using a capacitor with electrodes and a gap, incorporating a temperature-responsive material that migrates in response to threshold temperatures, causing a change in capacitance that can be detected by an RFID tag system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a temperature indicator provides immediate response to temperature changes, then the response speed is improved, but it cannot detect prolonged exposure to high temperatures
Solution Approach 1:
The temperature-responsive material is pre-positioned in a holder that is spatially separated from the capacitor. This preliminary positioning allows the system to distinguish between brief and prolonged temperature exposures, as the material requires time to migrate from the holder to the capacitor, thereby enabling detection of prolonged exposure while maintaining response capability
Solution Approach 2:
The patent introduces a temporal dimension to the temperature detection by creating a delay mechanism through the physical path between the holder and capacitor. This transforms the detection from a simple presence/absence indicator to a time-integrated measurement, where the migration time of the material provides information about the duration of temperature exposure
2Loss of time
If the temperature responsive material is placed close to the capacitor, then the response time is reduced, but the delay function is compromised
Solution Approach 1:
The system is segmented into distinct functional zones: a holder region for the temperature-responsive material and a capacitor region for signal detection. The physical separation creates a controlled migration path that provides the necessary delay, while the segmented structure allows for optimized positioning of each component to balance response time and delay requirements
3Measurement precision
If the temperature responsive material migrates into the capacitor gap, then the capacitance change is enhanced, but the structural complexity increases
Solution Approach 1:
The temperature-responsive material acts as an intermediary that translates thermal exposure into electrical signal changes. By positioning this material to migrate into the capacitor gap, the system achieves enhanced capacitance sensitivity without requiring complex sensing electronics, as the material itself serves as the transduction mechanism
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 an irreversible indication of temperature exposure, allowing for timely detection of product degradation and ensuring the quality of temperature-sensitive items.
Implementation Method 1
The first temperature responsive material is configured to migrate along the first path and into or along the gap in response to exposure to a temperature above a first threshold temperature
Implementation Method 2
The migration of the first temperature responsive material into or along the gap causes a change of the capacitance of the capacitor
Data Source
AI summary
A temperature exposure indicator includes a first temperature responsive material, a capacitor including a first electrode, a second electrode, and a gap between the first electrode and the second electrode, and a first path connecting the first temperature responsive material to the gap. The first temperature responsive material is configured to migrate along the first path and into or along the gap in response to exposure to a temperature above a first threshold temperature. The migration of the first temperature responsive material into or along the gap causes a change of the capacitance of the capacitor.