Gas Sensor Electrode Pore Size Optimization
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Solution Overview
Problem
Gas sensors with porous electrodes of large peak pore size exhibit low reactivity with detection gases, leading to increased electrode interface resistance and detection errors due to reduced three-phase interfaces between metal, solid electrolyte, and gas, which results in unstable sensor outputs.
Innovation Solution
A gas sensor element with a sensor electrode having a porous body containing a solid electrolyte and precious metal, where the peak pore size is adjusted to a range of 0.03 μm to 0.3 μm, increasing the three-phase interface and enhancing gas conversion efficiency while maintaining electrical conductivity and preventing peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the peak pore size of the sensor electrode is increased to relax internal forces and prevent peeling, then the electrode stability is improved, but the reactivity with detection gas deteriorates due to decreased three-phase interface
Solution Approach 1:
The patent applies parameter changes by precisely controlling the peak pore size within the range of 0.03 μm to 0.3 μm. This specific parameter range allows the electrode to maintain sufficient three-phase interface for high reactivity while also providing adequate pore space for stress relief, thus resolving the contradiction between stability and reactivity.
Solution Approach 2:
The sensor electrode is constructed as a composite material consisting of solid electrolyte and precious metal components with controlled porosity. This composite structure enables simultaneous achievement of high reactivity (through three-phase interface) and stability (through stress-relief pores), resolving the technical contradiction.
2Strength
If the peak pore size of the sensor electrode is increased to relax internal forces, then peeling is prevented, but the electrode interface resistance increases due to reduced three-phase interface
Solution Approach 1:
By changing the pore size parameter to a specific range (0.03 μm to 0.3 μm), the patent simultaneously achieves adequate electrode strength for preventing peeling while maintaining sufficient three-phase interface for low interface resistance and high detection precision.
3Stress or pressure
If the peak pore size of the sensor electrode is increased to relax internal forces, then internal stress is reduced, but the conversion efficiency of detection gas molecules into ions decreases
Solution Approach 1:
The patent resolves this contradiction by optimizing the peak pore size parameter to fall within 0.03 μm to 0.3 μm. This range provides sufficient pore volume for stress relief while maintaining adequate surface area and three-phase interface for high gas conversion efficiency.
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 adjusted peak pore size reduces electrode interface resistance, stabilizes sensor outputs, and minimizes detection errors by improving the conversion of detection gas molecules into ions, resulting in more accurate and consistent gas sensor readings.
Implementation Method 1
This increases the three-phase interface between a measurement gas, a precious metal in the sensor electrode, and a solid electrolyte. Thus, the measurement gas can be converted to ions in the sensor electrode with greater efficiency.
Implementation Method 2
a solid electrolyte body (2) having oxygen ion conductivity
Data Source
AI summary
A gas sensor element including a solid electrolyte body, a sensor electrode, and a reference electrode is provided. The solid electrolyte body has oxygen ion conductivity and includes a measurement gas surface to be exposed to a measurement gas introduced from the exterior and a reference gas surface to be exposed to a reference gas introduced from the exterior. The sensor electrode is provided on the measurement gas surface of the solid electrolyte body. The reference electrode is provided on the reference gas surface of the solid electrolyte body. The sensor electrode includes a porous body containing a solid electrolyte having oxygen ion conductivity and a precious metal, the peak pore size of the sensor electrode being 0.03 μm to 0.3 μm.