Composite Thermistor Coating for Tunable Baseline Resistance
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Solution Overview
Problem
Existing thermistor technologies are limited in their ability to modulate electrical properties, restricting their applicability to specific temperature ranges due to fixed conductivity levels, which hinders their use in various sensing applications.
Innovation Solution
A composite thermistor element is developed, comprising semiconducting ceramic particles with a core and an inorganic cover layer, where the cover layer's thickness and composition are controlled to modulate the baseline resistance without affecting the temperature-dependent resistance, allowing for a tailored resistance range suitable for different temperature regimes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the composition and doping level of ceramic particles are controlled to achieve desired conductivity, then the electrical conductivity is improved, but the temperature-dependent resistivity can no longer be changed, limiting the applicability to specific temperature ranges
Solution Approach 1:
The patent segments the particle structure into two distinct parts: a ceramic core maintaining temperature-dependent resistivity properties and a shell layer providing adjustable baseline conductivity. This segmentation allows each component to fulfill its specific function independently, resolving the contradiction between achieving desired conductivity and maintaining temperature range adaptability.
Solution Approach 2:
The patent employs composite materials by combining ceramic particles with a shell layer made of different material (metal oxide, semiconductor, or conductor). This composite structure enables the particle to exhibit both the temperature-dependent properties of the ceramic core and the conductivity characteristics of the shell, thereby achieving both improved electrical conductivity and extended temperature range applicability.
2Reliability
If a cover layer is added to particles to impose baseline resistance, then the electrical resistance is improved, but the temperature-dependent coefficient of resistance must be preserved
Solution Approach 1:
The patent applies local quality by assigning different functional properties to different regions of the particle: the core maintains high temperature-dependent sensitivity while the shell provides stable baseline resistance. This spatial differentiation of properties allows the particle to simultaneously achieve improved electrical resistance characteristics and preserve the temperature-dependent coefficient of resistance for accurate measurements.
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
This approach enables the selection of thermistors with desired electrical properties and temperature coefficients, extending their operational range without compromising sensitivity, thus enhancing their applicability in temperature sensing applications.
Implementation Method 1
The thickness of the cover layer is within a range that enables electron tunneling between cores of the contacting particles
Implementation Method 2
The particles have a core comprising a semiconducting ceramic material having temperature dependent resistance, e.g. a material specific temperature dependent coefficient of resistance
Data Source
AI summary
A composite thermistor element is described. The element includes a sensor material that is disposed between a pair of electrodes. The sensor material includes particles in a dielectric matrix. Each of the particles have: a core having a temperature dependent resistance, and a cover layer of an inorganic material. The particles form an electron conducting pathway between the electrodes having a temperature dependent resistance and a base-line resistance. Further aspects relate to a method of manufacturing the thermistor, the coated particles, a composition for use in the manufacturing of composite thermistors that includes the particles, and to a temperature sensor including the thermistor described herein.