Gas Sensor System Using FET Electrode Materials
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Solution Overview
Problem
Existing gas sensor systems are unable to effectively distinguish between different gases, particularly alkenes, which is crucial for applications such as monitoring ethylene levels in fruit ripening and flower opening processes.
Innovation Solution
A gas sensor system utilizing field-effect transistors with different source and drain electrodes, specifically a gold layer and an oxide layer, which provides an irreversible response to 1-MCP and a reversible response to ethylene, allowing for differentiation between these gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single type of field effect transistor is used for gas detection, then the device structure is simple, but the ability to distinguish between different gases is lost
Solution Approach 1:
The gas sensor system is segmented into multiple field effect transistor units, each with identical semiconductor layers but different source and drain electrode materials. This segmentation allows each transistor to respond differently to various gases, enabling gas differentiation while maintaining a relatively simple overall structure.
Solution Approach 2:
Different source and drain electrode materials are applied locally to specific field effect transistor units within the sensor system. This local differentiation in electrode composition creates distinct electrical responses to different gases at specific sensor locations, enabling precise gas identification.
2Measurement precision
If field effect transistors with different source and drain electrodes are used, then gas differentiation capability is improved, but the manufacturing complexity increases
Solution Approach 1:
The invention changes the material parameter of the source and drain electrodes across different field effect transistor units. By varying electrode materials (e.g., gold, silver, aluminum, copper) while keeping the semiconductor layer consistent, the system achieves enhanced gas differentiation without fundamentally altering the manufacturing process flow.
Solution Approach 2:
The sensor system employs composite material structures where different metal electrodes are combined with identical organic semiconductor layers in separate transistor units. This composite approach leverages the unique properties of different metals (work function, reactivity, conductivity) to create distinct gas response patterns while maintaining manufacturing efficiency.
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 accurate detection and differentiation of alkenes like ethylene and 1-MCP, facilitating controlled environments for fruit storage and flower maintenance by determining gas presence and concentration, and automatically triggering 1-MCP release when necessary.
Implementation Method 1
The use of thin film transistors as gas sensors is disclosed in, for example, Feng et al, 'Unencapsulated Air-stable Organic Field Effect Transistor by All Solution Processes for Low Power Vapor Sensing'
Implementation Method 2
The present inventors have surprisingly found that a field effect transistor having source and drain electrodes comprising a gold layer and an oxide layer gives an irreversible response in the presence of 1-MCP
Data Source
AI summary
A gas sensor system (100) comprising at least one first field effect transistor (200) comprising first source and drain electrodes and at least one second field effect transistor (300) comprising second source and drain electrodes different from the first source and drain electrodes. Different responses of the first and second FETs to gases in an environment may be used to differentiate between the gases, for example to differentiate between 1-methylcyclopropene and ethylene in locations where fruit is stored.