Rare Earth Oxide CO2 Sensor Selectivity
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Solution Overview
Problem
Current carbon dioxide gas sensors, particularly Non Dispersive Infrared (NDIR) sensors, are expensive and bulky, making them difficult to install, and there is a need for a high-performance, cost-effective chemoresistive CO2 gas sensor with a simple structure.
Innovation Solution
A carbon dioxide gas sensor utilizing a gas sensing layer composed of rare earth oxides with a cubic crystal structure, such as Sm2O3, Eu2O3, Dy2O3, Er2O3, or Yb2O3, which are used alone as chemoresistive materials without semiconductor components like SnO2, enhancing selectivity against interfering gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If NDIR CO2 gas sensor is used, then detection accuracy is improved, but device size and cost increase
Solution Approach 1:
The patent extracts and eliminates the semiconductor component (SnO2) from the traditional composite sensing layer, using only rare earth oxide. This simplification reduces device complexity and size while maintaining CO2 detection capability through the specific cubic crystal structure of rare earth oxide that provides high selectivity.
Solution Approach 2:
The patent changes the crystal structure parameter of the sensing material by selecting rare earth oxide with cubic crystal structure (space group Ia-3) instead of conventional materials. This parameter change enables high CO2 selectivity without requiring complex composite structures, thereby reducing device size while maintaining detection accuracy.
2Measurement precision
If NDIR CO2 gas sensor is used, then detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent removes the semiconductor component from the composite material system, using pure rare earth oxide with cubic crystal structure. This simplification reduces material costs and manufacturing complexity while achieving high CO2 detection accuracy through the inherent properties of the cubic rare earth oxide structure.
Solution Approach 2:
By changing to cubic crystal structure of rare earth oxide, the patent achieves high CO2 selectivity with a simpler material system that is easier and cheaper to manufacture compared to composite semiconductor materials, while maintaining high detection accuracy.
3Measurement precision
If composite material with semiconductor is used, then sensitivity is improved, but selectivity against interfering gases deteriorates
Solution Approach 1:
The patent extracts and removes the semiconductor component (SnO2) that causes poor selectivity, retaining only rare earth oxide with cubic crystal structure. This elimination resolves the selectivity problem while maintaining sensitivity through the optimized cubic structure that specifically interacts with CO2 molecules.
Solution Approach 2:
The patent changes the material composition parameter by using pure rare earth oxide with cubic crystal structure instead of composite semiconductor materials. This parameter change provides inherent selectivity against interfering gases (H2, CO, ethanol) while maintaining high sensitivity to CO2 through the specific crystallographic properties.
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 solution provides a compact, high-performance CO2 gas sensor with improved selectivity and stability, capable of detecting CO2 while distinguishing it from other gases like H2, CO, and ethanol, with enhanced durability and sensitivity.
Implementation Method 1
a gas sensing layer which contains a rare earth oxide... the rare earth oxide comprises a rare earth oxide having a cubic crystal structure as a main component
Data Source
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Figure 3A~3C
Figure 4~5
AI summary
A highly stable gas sensor capable of detecting carbon dioxide is provided. A carbon dioxide gas sensor includes an insulating substrate and a gas sensing layer formed on one major surface of the insulating substrate via electrodes, in which the gas sensing layer comprises one or more rare earth oxides represented by Ln2O3, Ln being at least one rare earth metal element selected from Sc, Y, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Pr, Yb and Lu, and a method for producing the gas sensor are provided.