Polymer Thermistor Film for Stable Flexible Temperature Sensing
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Solution Overview
Problem
Conventional thermistor-type temperature sensor elements using inorganic semiconductor thermistors lack flexibility and exhibit poor repeating stability of electric resistance values, which is essential for reliable temperature measurement across varying environmental temperatures.
Innovation Solution
A thermistor-type temperature sensor element with a temperature-sensitive film composed of a matrix resin and conductive domains, where the conductive domains include a conjugated polymer and a dopant, specifically a polyaniline-based polymer with a limited number of structural units (65 or less) and a molecular weight distribution of 1.2 or less, enhancing the stability of electric resistance values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic semiconductor thermistor is used in the temperature-sensitive film, then the temperature sensor element exhibits stable electric resistance characteristics, but the sensor element lacks flexibility and has poor repeating stability of electric resistance values
Solution Approach 1:
The patent changes the fundamental material parameter from inorganic semiconductor to conjugated polymer, which fundamentally alters the material properties to achieve both flexibility and improved repeating stability. The conjugated polymer's molecular structure and doping state are specifically controlled to achieve stable electric resistance characteristics while maintaining flexibility.
Solution Approach 2:
The temperature-sensitive film is constructed as a composite material combining conjugated polymer (providing conductivity and flexibility) with matrix resin (providing structural support). This composite structure enables the sensor to achieve both the flexibility needed for adaptability and the stable electric resistance characteristics needed for reliability.
2Reliability
If the number of structural units in the conjugated polymer is increased to improve conductivity, then the electric resistance decreases, but the repeating stability of the electric resistance value deteriorates
Solution Approach 1:
The patent identifies the number of structural units as a critical parameter and optimizes it to 65 or less. This specific parameter range achieves the optimal balance between maintaining sufficient conductivity and ensuring repeating stability, preventing the electric resistance value from drifting due to environmental factors while keeping the resistance at usable levels.
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 proposed solution provides a temperature sensor element with improved repeating stability of electric resistance values, ensuring accurate temperature measurement across varying temperatures by reducing the influence of external factors like water and heat.
Implementation Method 1
the conductive domains include a conjugated polymer and a dopant
Implementation Method 2
a temperature-sensitive film disposed in contact with the pair of electrodes... the same electric resistance value as the electric resistance value exhibited at the initial temperature can be exhibited when the temperature of the object reaches the same temperature as the initial temperature
Data Source
AI summary
There is provided a temperature sensor element including a pair of electrodes and a temperature-sensitive film disposed in contact with the pair of electrodes, in which the temperature-sensitive film includes a matrix resin and a plurality of conductive domains contained in the matrix resin, the conductive domains include a conjugated polymer and a dopant, and the number of structural units constituting the conjugated polymer is 65 or less.