Gas Sensor Electrode Spacing to Reduce Gold Evaporation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing gas sensor devices suffer from a reduction in accuracy for measuring nitrogen oxides (NOx) due to the evaporation and adhesion of gold (Au) from the pump electrode to the sensor electrode, leading to decreased decomposition activity.
Innovation Solution
The gas sensor device is designed with a diffusion controlling portion and a pump cell downstream of the diffusion controlling portion, where the pump electrode is positioned at least 0.2 mm away from the diffusion controlling portion in the gas flow direction, minimizing the evaporation and adhesion of Au to the sensor electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pump electrode is positioned close to the diffusion controlling portion, then the device complexity is reduced, but gold evaporation and adhesion to the sensor electrode increases, reducing measurement precision
Solution Approach 1:
The patent introduces a protective layer (intermediary substance) between the pump electrode and the sensor electrode. This protective layer acts as a mediator that prevents gold atoms evaporated from the pump electrode from adhering to the sensor electrode, thereby maintaining measurement precision while allowing the electrodes to be positioned closer together.
Solution Approach 2:
The protective layer is designed as a consumable component that can be replenished. When the protective layer becomes saturated with evaporated gold or deteriorates, it can be replaced to restore the sensor's performance, rather than requiring complex repositioning or replacement of entire electrode assemblies.
2Length of moving object
If the pump electrode is positioned close to the diffusion controlling portion, then the length of the gas flow path is reduced, but gold evaporation increases, leading to loss of substance
Solution Approach 1:
The protective layer serves as an intermediary barrier that captures evaporated gold atoms before they can be lost from the system or contaminate other components. This allows the pump electrode to be positioned closer to the diffusion controlling portion, shortening the gas flow path, while the protective layer prevents gold loss through adhesion to the sensor electrode.
Solution Approach 2:
The patent converts the harmful effect of gold evaporation into a controlled process by directing the evaporated gold atoms to adhere to the protective layer instead of the sensor electrode. The protective layer essentially 'soaks up' the evaporated gold, transforming a detrimental phenomenon into a manageable aspect of device operation that can be addressed through periodic maintenance.
3Volume of moving object
If the pump electrode is positioned close to the diffusion controlling portion, then the device size is reduced, but the decomposition activity of the sensor electrode decreases due to gold adhesion
Solution Approach 1:
The protective layer acts as a physical barrier that prevents gold atoms from the pump electrode from reaching and adhering to the sensor electrode. This intermediary layer allows the electrodes to be positioned closer together, reducing device size, while maintaining the sensor electrode's decomposition activity by blocking the contaminating gold atoms.
Solution Approach 2:
The protective layer is applied locally to specific areas where gold adhesion would be most problematic, particularly in the region between the pump electrode and sensor electrode. This localized protection maintains the sensor electrode's decomposition activity without requiring complete coverage of the entire device, thus minimizing the impact on device size.
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 configuration enhances the accuracy of NOx measurement by reducing Au evaporation and adhesion, thereby improving the decomposition activity and overall measurement precision.
Implementation Method 1
a diffusion controlling portion (50, 10b) which is formed to face the major surface and works to control a rate of diffusion of the measurement gas entering the measurement gas chamber
Implementation Method 2
a pump cell (40) which has a pump electrode (41) which contains gold, is formed on the major surface, and located downstream of the diffusion controlling portion in the gas flow direction, the pump cell working to regulate a concentration of oxygen in the measurement gas upon application of voltage to the pump electrode
Implementation Method 3
a sensor cell (20) which has a sensor electrode (21) formed on the major surface downstream of the diffusion controlling portion in the gas flow direction, the sensor cell working to measure a concentration of nitrogen oxide contained in the measurement gas upon application of voltage to the sensor electrode
Implementation Method 4
the measurement gas which has passed the second diffusion-controlling portion facing the surface on which the pump electrode is formed hits an upstream portion of the pump electrode in the gas flow direction, thereby resulting in evaporation of Au. Adhesion of the evaporated Au to the sensor electrode
Data Source
AI summary
A gas sensor device is equipped with a diffusion controlling portion, a pump cell, and a sensor cell. The diffusion controlling portion is formed to face a major surface of a solid electrolyte body and works to control a rate of diffusion of a measurement gas entering a measurement gas chamber. The pump cell has a pump electrode which contains gold and is formed on the major surface. The pump electrode is located downstream of the diffusion controlling portion in a gas flow direction. The pump cell works to regulate a concentration of oxygen in the measurement gas upon application of voltage to the pump electrode. The sensor cell has a sensor electrode formed on the major surface downstream of the diffusion controlling portion in the gas flow direction. The sensor cell works to measure a concentration of nitrogen oxide contained in the measurement gas upon application of voltage to the sensor electrode. The pump electrode is disposed upstream of the sensor electrode at a distance of 0.2 mm or more downstream away from the diffusion controlling portion in the gas flow direction. This enhances the accuracy in measuring the concentration of NOx.