Porous Solid Electrolyte Assembly for Membrane-Free Oxygen Sensing
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Solution Overview
Problem
Conventional limiting current type gas sensors require a separate porous membrane, leading to a complex production process and increased lead time, often involving methods like oblique deposition or plasma spraying.
Innovation Solution
A solid electrolyte assembly with a gas-permeable porous first electrode integrated directly with the substrate, eliminating the need for a separate porous membrane, and featuring a specific ratio of electrode overlap areas to ensure efficient oxygen diffusion and linear current-oxygen concentration relationship.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a planar solid electrolyte is used to simplify the structure, then device complexity is reduced, but the oxygen concentration gradient across the electrolyte cannot be established, worsening measurement precision
Solution Approach 1:
The patent transitions from a planar solid electrolyte configuration to a three-dimensional tubular configuration. The solid electrolyte is formed as a tube with inner and outer surfaces, creating a radial geometry that allows oxygen concentration gradients to develop across the wall thickness while maintaining structural simplicity. This dimensional change enables the establishment of concentration gradients perpendicular to the gas flow direction.
Solution Approach 2:
The patent employs porous coating layers on the inner and outer surfaces of the tubular solid electrolyte. These porous layers allow gas permeation while maintaining the structural integrity of the tube. The porous structure enables oxygen to diffuse through the electrolyte wall, creating the necessary concentration gradient for measurement while preserving the simplified tubular geometry.
2Measurement precision
If a tubular solid electrolyte is used to establish oxygen concentration gradient, then measurement precision is improved, but manufacturing complexity increases, worsening ease of manufacture
Solution Approach 1:
The patent employs screen printing as a manufacturing technique to form the tubular solid electrolyte structure. This process allows for direct deposition of electrolyte material onto a support structure in the desired tubular configuration. By controlling printing parameters such as screen mesh size, printing pressure, and firing conditions, the electrolyte can be formed with appropriate wall thickness and porosity, simplifying the manufacturing of complex tubular geometries.
3Productivity
If porous coating layers are added to the tubular electrolyte to enable gas permeation, then gas transport is improved, but structural complexity increases, worsening device complexity
Solution Approach 1:
The patent combines the support structure and the porous functional layers into an integrated assembly. The porous coating layers are directly applied to and bonded with the tubular support structure through sintering or firing processes. This merging eliminates the need for separate support structures and porous layers, reducing assembly steps and overall device complexity while maintaining effective gas permeation pathways through the electrolyte wall.
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 allows for a simpler structure, reduced production time, and effective oxygen concentration measurement at low temperatures and voltages, suppressing sensor deterioration while maintaining linear current-oxygen dependence.
Implementation Method 1
a solid electrolyte assembly (300) comprising a solid electrolyte membrane (310) and a pair of electrodes (320, 330) disposed on opposite sides of the solid electrolyte membrane (310), wherein the solid electrolyte membrane (310) transforms chemical energy to electrical energy through electrochemical reactions
Implementation Method 2
The solid electrolyte assembly enables the construction of a limiting current-type gas sensor that is simple in structure, easy to manufacture, and highly accurate in measurement
Data Source
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AI summary
A solid electrolyte assembly includes a substrate, a solid electrolyte, and a first electrode and a second electrode. The solid electrolyte has oxide ion conductivity, and the first electrode is located under the solid electrolyte and contains a porous material. The first electrode has only one oxygen diffusion path that is formed overlapping the substrate and the solid electrolyte. When Sr represents the smallest cross-sectional area that is a cross-sectional area of the oxygen diffusion path at a location where the area of a cross section of the first electrode taken perpendicularly to an oxygen diffusing direction is smallest in a portion of the oxygen diffusion path where the oxygen diffusion path overlaps the substrate and the solid electrolyte in a plan view of the solid electrolyte assembly, and Sp represents the area of a region where the first electrode and the second electrode overlap each other in a plan view of the solid electrolyte, Sr/Sp is from 1×10-7 to 6.9×10-4.