Mixed-Potential Gas Sensor with Segmented Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gas sensors are limited in measuring hydrocarbon gas concentrations beyond 2000 ppmC and cannot accurately detect a wide range of concentrations, from low to high, which is necessary for diagnosing exhaust emission control system failures in engines.
Innovation Solution
A mixed-potential gas sensor with a sensor element made of an oxygen-ion conductive solid electrolyte and multiple sensing electrodes with different Au abundance ratios, including a first sensing electrode with an Au abundance ratio of 0.7 or more and a second sensing electrode with an Au abundance ratio of 0.1 to 0.7, allowing for precise measurement of hydrocarbon gas concentrations across a broader range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single sensing electrode with fixed Au abundance ratio is used, then the sensor can accurately measure hydrocarbon gas concentration in a specific range, but it cannot measure a wide concentration range from low to high
Solution Approach 1:
The sensing electrode is divided into multiple regions with different Au abundance ratios (first region with 0.01-0.3, second region with 0.3-0.7, third region with 0.7-1.0). Each region is optimized for different concentration ranges, enabling the single electrode to measure a wide concentration range from low to high while maintaining measurement accuracy in each segment.
Solution Approach 2:
Different regions of the sensing electrode have different local compositions (Au abundance ratios) tailored to specific measurement needs. The first region with lower Au abundance is suitable for high concentration measurement, while regions with higher Au abundance are suitable for low concentration measurement, allowing each part to perform its function optimally.
2Measurement precision
If the Au abundance ratio in the sensing electrode is increased to enhance sensitivity, then the detection ability for low concentration improves, but the measurement capability for high concentration deteriorates
Solution Approach 1:
The sensing electrode is segmented into multiple regions with progressively increasing Au abundance ratios. This segmentation allows the electrode to simultaneously provide high sensitivity for low concentration detection (in regions with higher Au abundance) and maintain measurement capability for high concentration (in regions with lower Au abundance), resolving the trade-off between sensitivity and range coverage.
3Reliability
If the Au abundance ratio is set to enhance selective decomposition ability for oxygen, then the sensor performance for oxygen detection improves, but the electrode impedance increases when Au abundance ratio exceeds 0.3
Solution Approach 1:
The sensing electrode is divided into regions with different Au abundance ratios to balance oxygen decomposition ability and impedance. Regions with Au abundance ratio of 0.01-0.3 provide good electrical conductivity with adequate oxygen decomposition, while regions with 0.3-0.7 provide enhanced oxygen decomposition ability. This segmentation allows the electrode to maintain overall low impedance while having sufficient oxygen decomposition capability in specific regions.
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
Enables accurate measurement of hydrocarbon gas concentrations from 0 to 10000 ppmC, overcoming the limitations of conventional sensors by utilizing the varying Au abundance ratios to enhance sensitivity characteristics for different concentration ranges.
Implementation Method 1
a sensor element mainly made of an oxygen-ion conductive solid electrolyte
Implementation Method 2
a catalytic activity against a hydrocarbon gas is disabled, inducing a mixed potential having correlation with the concentration of the hydrocarbon gas
Data Source
AI summary
A mixed-potential gas sensor for measuring a concentration of a predetermined gas component of a measurement gas includes sensing electrodes mainly made of an oxygen-ion conductive solid electrolyte and located on a surface of a sensor element, and at least one reference electrode including a cermet including Pt and an oxygen-ion conductive solid electrolyte. The sensing electrodes each include a cermet including a noble metal and an oxygen-ion conductive solid electrolyte. The noble metal includes Pt and Au. A Au abundance ratio, which is an area ratio of a portion covered with the Au to a portion at which the Pt is exposed in a surface of noble metal particles forming each of the sensing electrodes, differs among the sensing electrodes. The gas sensor determines a concentration of the predetermined gas component based on a potential difference between each of the sensing electrodes and the at least one reference electrode.