Single-Chamber CO Sensor Using Short-Circuit Current Detection

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Solution Overview

Problem

Existing carbon monoxide gas sensors face issues with complex structures and insufficient measurement accuracy, particularly in high-temperature environments, and are susceptible to combustible gases other than carbon monoxide.

Innovation Solution

A single-chamber carbon monoxide gas sensor utilizing an anion-conductive solid electrolyte layer with a first electrode active for carbon monoxide oxidation and a second electrode less active for oxidation, measuring a short-circuit current between the electrodes, and employing a solid electrolyte layer with a rare-earth oxide and specific complex oxide compositions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a two-chamber type sensor is used to isolate electrode atmospheres, then measurement accuracy is improved, but device complexity increases due to airtight structure requirements

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidstructure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the atmosphere exposure for both sensing electrode and counter electrode into a single chamber, eliminating the need for complex airtight isolation structures while maintaining measurement functionality through the solid electrolyte's selective ion conduction properties

Inventive Principle:

Principle #5Merging (Combining)

2Measurement precision

If voltage measurement method is used as in JP 2012-42222A, then measurement capability is achieved, but sufficient voltage value cannot be obtained resulting in insufficient measurement accuracy

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidvoltage value

Core Design Contradiction:

Measurement precisionVSPower

Solution Approach 1:

The patent replaces the voltage measurement method with a short-circuit current measurement method, utilizing the electrochemical reaction between carbon monoxide and oxygen on the electrodes to generate measurable current signals that provide sufficient measurement accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If controlled potential electrolysis gas sensor is used in high-temperature environment, then carbon monoxide measurement capability is achieved, but lifespan is reduced due to electrolyte solution degradation

Engineering Contradiction:

Improvemeasurement capabilityVSAvoidlifespan

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent transitions from using liquid electrolyte solution to solid electrolyte, eliminating the phase change and chemical degradation issues that occur in high-temperature environments, thereby extending sensor lifespan while maintaining measurement capability

Inventive Principle:

Principle #36Phase transitions

4Speed

If semiconductor type gas sensor is used, then response speed is improved, but susceptibility to combustible gases other than carbon monoxide increases

Engineering Contradiction:

Improveresponse speedVSAvoidsusceptibility to interfering gases

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by using a solid electrolyte with specific ionic conduction properties that selectively allows oxide ion transport, creating a localized chemical environment that enables carbon monoxide-specific detection while maintaining fast response characteristics

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

The sensor achieves high measurement accuracy and a simple structure, enabling accurate carbon monoxide gas concentration detection over a wide range, even at low concentrations, without the need for hermetic isolation of electrode atmospheres.

Implementation Method 1

an anion-conductive solid electrolyte layer

Methodology Applied

Scientific EffectOxide ion conduction: Conduction (electrical)

Implementation Method 2

the first electrode is active for oxidation of carbon monoxide gas

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 3

the carbon monoxide gas sensor is configured to measure a short-circuit current between the electrodes

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Data Source

PatentUS12578298B2Carbon monoxide gas sensor

Publication Date: 2026.03.17 MITSUI MINING & SMELTING CO LTD

AI summary

A carbon monoxide gas sensor is a single-chamber sensor for measuring the carbon monoxide gas concentration in a gas phase. The carbon monoxide gas sensor has electrodes disposed on respective sides of a solid electrolyte layer. One of the electrodes is active for oxidation of carbon monoxide gas, and the other of the electrodes is more inactive for oxidation of carbon monoxide gas than the one electrode. The carbon monoxide gas sensor is configured to measure a short-circuit current between the electrodes. In the carbon monoxide gas sensor, the solid electrolyte layer has oxide ion conductivity.