FET Gas Sensor With Electrochemical Interference Removal
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Solution Overview
Problem
Field effect transistor (FET) gas sensors often measure interfering gases, leading to distorted target gas measurements due to superimposed signals and decreased signal levels, with existing methods like optimizing materials, reference sensors, and filters facing limitations such as cross-sensitivity and operational temperature constraints.
Innovation Solution
Incorporating an electrochemical element within the gas channel of the FET sensor to selectively convert interfering gases into non-interfering components, allowing target gases to pass through for detection, using active electrodes and ion conductors to manage gas flow and conversion at typical operating temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a filter is used to suppress interference from interfering gases, then measurement accuracy is improved, but the filter capacity is limited and requires replacement or regeneration
Solution Approach 1:
The sensor system performs self-diagnosis and self-monitoring by comparing measurements from the gas-sensitive layer with reference measurements, automatically detecting filter saturation and triggering replacement alerts without external intervention
Solution Approach 2:
The patent replaces passive mechanical filters with active electrochemical conversion elements that continuously transform interfering gases, providing unlimited service life without saturation
2Object-affected harmful factors
If catalytic filter is used to transform interfering gases, then interference suppression is improved, but operating temperature must be above 300° C. which exceeds silicon chip limits
Solution Approach 1:
The patent changes the operating temperature parameter from high-temperature catalytic conversion (>300°C) to low-temperature electrochemical conversion (<150°C), enabling compatibility with silicon chip constraints while maintaining interference suppression effectiveness
Solution Approach 2:
The patent substitutes thermal catalytic conversion with electrochemical conversion, replacing the heat-based mechanism with an electricity-based mechanism that operates at lower temperatures
3Measurement precision
If reference sensor is used to compensate for interfering gases, then measurement accuracy is improved, but cross-sensitivity limits the compensation effectiveness
Solution Approach 1:
The patent introduces electrochemical conversion elements as intermediary components that actively transform interfering gases before they reach the sensor, providing more effective compensation than passive reference sensors
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 approach enhances selectivity by removing interfering gases, preventing filter saturation, enabling stable long-term operation and self-monitoring, and improving measurement accuracy by minimizing incorrect signals.
Implementation Method 1
an electrochemical element is at least partially disposed within the gas channel to at least one of electrochemically convert interfering gases and activate a target gas
Implementation Method 2
The gas-sensitive layer 16 is adapted such that its surface potential changes upon contact with a gas within the air gap 14, and thus controls the transistor 12
Implementation Method 3
The FET gas sensor has a gas channel for diffusion of a gas to be measured to a gas-sensitive layer that is in active connection with a field effect transistor for readout of a measurement signal, in which an electrochemical element is at least partially disposed within the gas channel
Data Source
AI summary
An operating method is disclosed for the selective detection of a target gas in a gas mixture to be measured by a field effect transistor with a gas-sensitive layer disposed on a carrier substrate, wherein the gas mixture to be measured is prepared by an electrochemical element such that the measured gas mixture includes minimal amounts of interfering gases that interfere with the measurement of the target gas, and/or at least one target gas is activated such that it is detected by the gas-sensitive layer.