Gas Sensor Electrode Overlap for Thermoelectromotive Force Stabilization
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Solution Overview
Problem
Gas sensors face reduced detection accuracy due to unstable thermoelectromotive forces caused by temperature variations between reference and measurement electrodes, leading to prolonged stabilization times and steady thermoelectromotive forces.
Innovation Solution
A sensor element design with a reference electrode center of gravity overlapping the measurement electrode, both having lengths less than or equal to 1.1 mm in the front-rear direction, and a distance between them of 50 μm to 500 μm in the thickness direction, along with a reference electrode area greater than or equal to 1.0 mm², to reduce temperature differences and stabilize thermoelectromotive forces quickly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the length of reference electrode and measurement electrode in the front-rear direction is increased, then the steady thermoelectromotive force decreases, but the stabilization time of thermoelectromotive force increases
Solution Approach 1:
The patent optimizes the length parameter of electrodes in the front-rear direction to be less than or equal to 1.1 mm, and sets the area of reference electrode to be greater than or equal to 1.0 mm². These parameter changes achieve a balance between reducing steady thermoelectromotive force and shortening stabilization time.
Solution Approach 2:
The patent positions the center of gravity of the reference electrode to overlap with the measurement electrode as viewed in the thickness direction. This spatial arrangement in the thickness dimension reduces temperature differences between electrodes without requiring changes in the front-rear length, thereby reducing steady thermoelectromotive force without increasing stabilization time.
2Measurement precision
If the length of reference electrode and measurement electrode in the front-rear direction is increased, then the steady thermoelectromotive force decreases, but the detection accuracy is reduced due to prolonged stabilization time
Solution Approach 1:
The patent specifies that the length of both reference electrode and measurement electrode in the front-rear direction should be less than or equal to 1.1 mm, and the area of reference electrode should be greater than or equal to 1.0 mm². These parameter optimizations simultaneously reduce steady thermoelectromotive force and maintain short stabilization time, thereby preserving detection accuracy.
Solution Approach 2:
By overlapping the center of gravity of the reference electrode with the measurement electrode in the thickness direction view, the patent reduces temperature differences between electrodes through spatial arrangement in the thickness dimension, achieving reduced steady thermoelectromotive force without the penalty of increased stabilization time.
3Measurement precision
If the area of reference electrode is increased, then the steady thermoelectromotive force decreases, but the manufacturing precision requirements increase
Solution Approach 1:
The patent sets the area of the reference electrode to be greater than or equal to 1.0 mm², which reduces steady thermoelectromotive force. The overlapping center of gravity configuration in the thickness direction provides a clear positioning target, helping to maintain manufacturing precision during electrode fabrication and assembly.
Solution Approach 2:
The patent positions the center of gravity of the reference electrode to overlap with the measurement electrode as viewed in the thickness direction. This spatial relationship provides a clear alignment target that simplifies manufacturing and assembly processes, reducing the actual positioning precision requirements despite the larger electrode area.
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 shortens the stabilization time of thermoelectromotive forces and decreases their steady value, enhancing the detection accuracy of specific gas concentrations by minimizing residual voltages and preventing crack formation in the sensor element.
Implementation Method 1
a heater disposed in the element body and configured to heat the solid electrolyte layer
Implementation Method 2
an element body including an oxygen-ion-conductive solid electrolyte layer
Implementation Method 3
a voltage between both electrodes includes the thermoelectromotive force
Data Source
AI summary
A sensor element includes an element body including an oxygen-ion-conductive solid electrolyte layer, the element body having a longitudinal direction, a measurement electrode disposed in the element body, a reference electrode disposed in the element body so as to come into contact with a reference gas, and a heater configured to heat the solid electrolyte layer. A center of gravity of the reference electrode overlaps the measurement electrode as viewed in a thickness direction of the solid electrolyte layer. A length of each of the reference electrode and the measurement electrode in a front-rear direction is less than or equal to 1.1 mm, the front-rear direction being a direction along the longitudinal direction of the element body. An area of the reference electrode as viewed in the thickness direction is greater than or equal to 1.0 mm2.