Multi-Gas Sensor Reference Electrode Segmentation
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Solution Overview
Problem
Existing multi-gas sensors face challenges in reliably detecting multiple target gases in the presence of interfering gases, such as ethanol, and are susceptible to transient signals due to temperature changes, especially in miniaturized designs.
Innovation Solution
A multi-gas sensor design featuring two working electrodes made of different materials and a reference electrode with two single electrodes made of different materials, connected conductively, to minimize the influence of interfering gases and reduce transient signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mixed-metal reference electrode (platinum and iridium) is used for detecting multiple target gases, then the sensor can detect both gases, but a mixed potential develops that affects measurement accuracy
Solution Approach 1:
The reference electrode is divided into two separate single electrodes made of different metals (platinum and iridium), which are connected conductively. This segmentation allows each metal to respond to different gases independently, eliminating the mixed potential problem while maintaining multi-gas detection capability
Solution Approach 2:
Different regions of the reference electrode have different metal compositions tailored to specific gas detections. The platinum single electrode is optimized for certain gas responses while the iridium single electrode handles other gases, providing localized optimization of electrochemical properties
2Volume of moving object
If the sensor is miniaturized to reduce size, then portability is improved, but transient signals occur more frequently due to temperature changes
Solution Approach 1:
The electrode materials are selected and configured to have compensating temperature coefficients. By carefully choosing the metal compositions and their arrangements, the temperature-induced potential changes in different electrodes counterbalance each other, reducing transient signals while maintaining compact sensor design
3Adaptability or versatility
If platinum reference electrode is used, then gas detection is enabled, but the potential is strongly affected by ethanol and other alcohols causing false readings
Solution Approach 1:
The iridium single electrode acts as an intermediary that does not react with alcohols like ethanol. This non-reactive electrode provides a stable reference potential in the presence of interfering gases, allowing the sensor to distinguish between target gases and alcohol interferents
Solution Approach 2:
The reference electrode uses a composite structure with two different metals (platinum and iridium) that have different chemical properties. This composite approach combines the gas-detection capability of platinum with the alcohol-resistance of iridium
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 effectively minimizes the impact of interfering gases and reduces transient signals caused by temperature changes, enhancing its reliability and performance, especially in compact configurations.
Implementation Method 1
A reaction of the target gas, which can be used for obtaining qualitative and quantitative data by means of unambiguously measurable electrical variables on the basis of their selectivity and their accessibility, takes place at a measuring electrode reacting selectively with the gas to be detected
Implementation Method 2
The electrochemically active material of the reference electrode consists in this case, as a rule, either of iridium or of platinum or of a mixture of iridium and platinum
Implementation Method 3
Usual electrochemical gas sensors have a plurality of electrodes, which communicate with one another via an electrolyte
Data Source
AI summary
A multi-gas sensor includes a defined arrangement of working electrodes and a reference electrode. The reference electrode has two conductively connected single electrodes formed of respective different electrode materials. The working electrode and the single electrodes are preferably each disk-shaped and are arranged in two stacks one on top of another. A process is provided for a quantitative or qualitative determination of two target gases with the multi-gas sensor.