Gas Sensor Standard Lead Segmentation for Conductivity and Permeability

Solution Overview

Problem

In self-generating type gas sensors, balancing the electric connection property and oxygen permeability in the standard lead is challenging due to the conflicting requirements of increasing precious metal content for better conductivity and decreasing it for improved porosity and oxygen permeability.

Innovation Solution

The standard lead is divided into a lead portion for securing electric connection and a porous portion for oxygen permeability, with the lead portion formed primarily of precious metal and the porous portion formed primarily of ceramic, allowing for individual optimization of their functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the precious metal content in the standard lead is increased to improve electric connection property, then the conductivity is improved, but the porosity and oxygen permeability decrease

Engineering Contradiction:

Improveelectric connection propertyVSAvoidoxygen permeability

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The standard lead is divided into two distinct portions: a lead portion made of precious metal for electrical connection and a porous portion made of ceramic material for oxygen permeability. This segmentation allows each portion to be optimized for its specific function without compromise, resolving the contradiction between conductivity and oxygen permeability requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the standard lead are assigned different material compositions and properties. The lead portion uses precious metal with high conductivity but low porosity, while the porous portion uses ceramic material with high oxygen permeability but lower conductivity. This local differentiation of quality allows simultaneous optimization of both electric connection and oxygen supply functions.

Inventive Principle:

Principle #3Local quality

2Quantity of substance

If the precious metal content in the standard lead is decreased to improve porosity and oxygen permeability, then the oxygen permeability is improved, but the electric connection property decreases

Engineering Contradiction:

Improveoxygen permeabilityVSAvoidelectric connection property

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The standard lead is divided into two distinct portions: a lead portion made of precious metal for electrical connection and a porous portion made of ceramic material for oxygen permeability. This segmentation allows each portion to be optimized for its specific function without compromise, resolving the contradiction between conductivity and oxygen permeability requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the standard lead are assigned different material compositions and properties. The lead portion uses precious metal with high conductivity but low porosity, while the porous portion uses ceramic material with high oxygen permeability but lower conductivity. This local differentiation of quality allows simultaneous optimization of both electric connection and oxygen supply functions.

Inventive Principle:

Principle #3Local quality

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 enhances the electric connection property of the lead portion while improving the oxygen permeability of the porous portion, facilitating easier design and stabilizing oxygen flow rates, thereby improving the overall performance of the gas sensor.

Implementation Method 1

oxygen ions move from the detection electrode to the standard electrode

Methodology Applied

Scientific EffectOxygen ion conduction: Conduction (electrical)

Implementation Method 2

a porous portion, which extends to the inner portion of the sensor element along the surface of the solid electrolyte body, has a gas permeability higher than that of the lead portion

Methodology Applied

Scientific EffectGas permeation: Permeation

Data Source

PatentUS9513251B2Gas sensor

Publication Date: 2016.12.06 NITERRA CO LTD

AI summary

A gas sensor having a sensor element including: a plate-shaped solid electrolyte body; and a pair of electrodes sandwiching the electrolyte body. The electrodes include a measurement electrode portion, and a standard electrode portion disposed in an inner portion of the sensor element. A lead portion, which extends along the surface of the solid electrolyte body, is connected to the standard electrode portion. The standard electrode portion is mainly formed with a precious metal and contains a ceramic. The lead portion is mainly formed of a precious metal and has a ceramic content smaller than the standard electrode portion. A porous portion, which extends to the inner portion of the sensor element along the surface of the solid electrolyte body, has a gas permeability higher than the lead portion, is mainly formed with a ceramic, and is connected to the standard electrode portion.