Ionic Liquid Temperature Switch for Low Threshold Detection
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Solution Overview
Problem
Existing temperature switches using eutectic salt mixtures often have melting points above 200°C, are moisture sensitive, and exhibit small conductivity changes, making them unsuitable for applications requiring lower threshold temperatures and stable operation.
Innovation Solution
A temperature switch utilizing an ionic liquid with a melting point below 200°C, specifically an ionic liquid composed of an organic cation and an anion like imidazolium and tris-(pentafluoroethyl) trifluorophosphate, which provides a sharp and reversible impedance change, ensuring reliable detection of temperature thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If eutectic salt mixtures are used in temperature switches, then the device can detect temperature changes, but the melting point is above 200°C and the device is moisture sensitive
Solution Approach 1:
The patent changes the chemical composition parameters of the sensing material from traditional eutectic salt mixtures to ionic liquids with specific organic cations and inorganic anions. This parameter change enables the material to have both low melting point (below 200°C) and high chemical stability with hydrophobicity, resolving the contradiction between low threshold temperature detection and reliability against moisture sensitivity.
Solution Approach 2:
The patent uses composite ionic liquid materials composed of specific organic cations (such as imidazolium, pyridinium, pyrrolidinium, phosphonium, or ammonium) and inorganic anions (such as BF4-, PF6-, CF3SO3-, or AlCl4-). This composite material structure provides both low melting point for low threshold detection and high chemical stability for moisture resistance, simultaneously addressing both requirements.
2Measurement precision
If eutectic salt mixtures are used, then temperature detection is possible, but the conductivity change is small
Solution Approach 1:
The patent changes the electrical conductivity parameter of the sensing material by using ionic liquids with high ionic mobility. These materials exhibit large changes in electrical conductivity across their melting point, providing a clear and detectable signal transition that improves measurement precision and signal clarity simultaneously.
3Temperature
If ionic liquids with melting point below 200°C are used, then low threshold temperature detection is achieved, but chemical stability may be compromised
Solution Approach 1:
The patent employs specifically designed composite ionic liquid structures where hydrophobic organic cations (such as imidazolium, pyridinium, pyrrolidinium, phosphonium, or ammonium) are combined with stable inorganic anions (such as BF4-, PF6-, CF3SO3-, or AlCl4-). This composite structure achieves both low melting point (below 200°C) for low threshold detection and high chemical stability with hydrophobicity, resolving the apparent contradiction between low melting point and chemical stability.
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 ionic liquid-based temperature switch offers a low threshold temperature detection with high chemical stability, hydrophobicity, and significant conductivity change, enabling effective protection against overheating with minimal risk of damage or degradation.
Implementation Method 1
the ionic liquid 14 has a melting point at a threshold temperature... Below the threshold temperature, the ionic liquid 14 exists in a solid state... Above the threshold temperature, the ionic liquid 14 exists in a liquid state
Implementation Method 2
the ionic liquid 14 has a melting point at a threshold temperature which is higher than the temperature to which the temperature switch is normally exposed
Implementation Method 3
Below the threshold temperature, the ionic liquid 14 exists in a solid state and has a relatively low electrical conductivity (a high impedance). Above the threshold temperature, the ionic liquid 14 exists in a liquid state and has a relatively high electrical conductivity (low impedance)
Data Source
AI summary
A temperature switch comprises a material (14) which melts and concomitantly undergoes a change in an electrical characteristic at a predetermined temperature. The temperature switch also includes at least two electrical contacts (10,12) for detecting the change in the electrical characteristic. The material (14) comprises an organic cation and an anion and is preferably an ionic liquid.