Gas Sensor Blocking Layer Suppresses Oxygen Ion Migration
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Solution Overview
Problem
Existing gas sensors face accuracy issues due to electrode-less migration of oxygen ions, which occurs at higher temperatures or with significant oxygen concentration differences, leading to noise in current measurements and reduced accuracy in detecting specific gas concentrations.
Innovation Solution
Incorporating a blocking portion with an inner and outer blocking layer that covers exposed solid-electrolyte surfaces, these layers being non-conductive to oxygen-containing substances, thereby suppressing oxygen ion migration without electrode intervention, and optimizing the area ratio and thickness of these layers for enhanced effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor element uses a multilayer structure with solid-electrolyte layers for gas detection, then the detection capability is improved, but oxygen ion migration occurs through exposed solid-electrolyte surfaces without electrodes, causing measurement noise and reduced accuracy
Solution Approach 1:
The patent introduces a blocking layer as an intermediary substance between the exposed solid-electrolyte surface and the external environment. This blocking layer specifically prevents oxygen ion migration while allowing the sensor to maintain its detection function, thus resolving the contradiction between measurement precision and harmful oxygen ion migration.
Solution Approach 2:
The blocking layer is designed as a simple, easy-to-apply coating that can be deposited on the exposed surfaces. It serves as a sacrificial or protective layer that prevents oxygen ion migration without interfering with the core sensing mechanism, effectively eliminating measurement noise caused by electrode-less ion migration.
2Measurement precision
If the sensor operates at higher temperatures to enhance gas detection sensitivity, then the detection sensitivity is improved, but oxygen ion migration increases due to thermal activation, leading to more noise in current measurements
Solution Approach 1:
The blocking layer is applied in advance to the exposed solid-electrolyte surfaces before the sensor operates at high temperatures. This preliminary protective measure prevents thermally activated oxygen ion migration from occurring in the first place, allowing the sensor to operate at elevated temperatures for enhanced sensitivity without suffering from increased ion migration noise.
3Speed
If the exposed surface area of solid-electrolyte layers is increased to improve gas access, then the response speed is improved, but the area available for unwanted oxygen ion migration is also increased, causing more noise
Solution Approach 1:
The blocking layer is selectively applied to specific exposed surfaces of the solid-electrolyte layers where oxygen ion migration would occur, rather than uniformly coating all surfaces. This localized treatment prevents ion migration on surfaces exposed to the external environment while maintaining gas access pathways, thus preserving fast response speed without increasing noise from unwanted ion migration.
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 effectively suppresses electrode-less migration of oxygen ions, improving the accuracy of specific gas concentration detection by minimizing noise in current measurements and maintaining consistent oxygen concentrations within the sensor element.
Implementation Method 1
a blocking portion (65) is provided. The blocking portion (65) includes at least one of an inner blocking layer (66) and an outer blocking layer (67)... The inner blocking layer (66) and the outer blocking layer (67) do not each conduct one or more kinds of substances that contain oxygen... the migration of oxygen ions is suppressed
Implementation Method 2
a multilayer structure including fine oxygen-ion-conductive solid-electrolyte layers (4, 6)... the solid electrolyte is exposed... oxygen ions occasionally pass through the solid-electrolyte layer (6)
Data Source
Figure 1
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Figure 4~5
AI summary
A gas sensor includes a blocking portion 65 including an inner blocking layer 66 and outer blocking layer 67. The inner blocking layer 66 covers at least part of an exposed portion where solid-electrolyte layers are exposed as inner surfaces of a third internal cavity 61. The outer blocking layer 67 covers at least part of a nearest portion 6a that is at the shortest distance from the third internal cavity 61 among portions of outer surfaces of a multilayer structure where the solid-electrolyte layers are exposed. The inner blocking layer 66 and the outer blocking layer 67 do not each conduct one or more kinds of substances that contain oxygen. The outer blocking layer 67 covers the entirety of the nearest portion 6a. An area ratio A/B of a covered area A by which the blocking portion 65 covers the solid-electrolyte layers to an exposed area B by which the solid-electrolyte layers are exposed as the inner surfaces of the third internal cavity 61 is 0.3 or greater.