Two-Cell Electrochemical Sensor for Sulfur Oxide Detection
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Solution Overview
Problem
Existing gas concentration detecting devices face challenges in accurately measuring sulfur oxide (SOx) concentrations in exhaust gas from internal combustion engines due to low concentration levels and interference from other gases like oxygen and nitrogen oxides, making it difficult to distinguish and detect the decomposition current specific to sulfur oxide.
Innovation Solution
A gas concentration detecting device utilizing a two-cell limiting current-type gas sensor configuration, where the upstream cell removes oxygen and the downstream cell decomposes water and sulfur oxide at specific voltages, allowing for the separation of decomposition currents and accurate measurement of sulfur oxide concentration based on electrode current changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-cell gas sensor is used to detect sulfur oxide, then the device structure is simple, but the measurement precision is low due to interference from other gases
Solution Approach 1:
The sensor is divided into two separate electrochemical cells: an upstream cell that detects oxygen and a downstream cell that detects sulfur oxide. This segmentation allows each cell to be optimized for its specific detection function, with the upstream cell removing oxygen interference before the downstream cell measures SOx concentration, thereby resolving the contradiction between simple structure and precise measurement.
2Measurement precision
If the applied voltage is increased to enhance the decomposition current of sulfur oxide, then the detection sensitivity improves, but the interference from other oxygen-containing gases increases
Solution Approach 1:
The upstream electrochemical cell performs preliminary action by removing oxygen from the exhaust gas before it reaches the downstream cell. By applying a voltage to the upstream cell that causes oxygen decomposition, the system eliminates the primary interfering gas, allowing the downstream cell to measure sulfur oxide with higher sensitivity without excessive interference from other oxygen-containing gases.
3Measurement precision
If the upstream cell removes oxygen to reduce interference, then the measurement precision of SOx improves, but the device complexity increases
Solution Approach 1:
Two electrochemical cells are merged into a single integrated sensor assembly with a shared exhaust gas flow path. The upstream cell removes oxygen while the downstream cell measures sulfur oxide, and both functions are combined in one device structure. This merging approach achieves precise SOx measurement through oxygen removal while maintaining a relatively compact and integrated design rather than using separate independent systems.
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
Enables precise detection of sulfur oxide concentration in exhaust gas by isolating the decomposition current specific to sulfur oxide, reducing interference from other gases, and providing a high level of accuracy in SOx concentration measurement.
Implementation Method 1
the oxygen contained in the test gas becomes an oxide ion (O2−) through reductive decomposition. This oxide ion is conducted to the anode via the solid electrolyte body
Implementation Method 2
the flow rate of the test gas reaching the electrode (cathode) is limited by the diffusion resistance unit
Implementation Method 3
the oxygen contained in the test gas becomes an oxide ion (O2−) through reductive decomposition
Data Source
AI summary
A gas concentration detecting device includes a gas concentration detecting element and an electronic control unit. The gas concentration detecting element includes a first electrochemical cell and a second electrochemical cell. The electronic control unit is configured to detect the concentration of the sulfur oxide contained in the test gas based on a first detected value correlated with a current flowing through the first electrochemical cell acquired when a first removing voltage is applied to the second electrochemical cell and a measuring voltage is applied to the first electrochemical cell.