Graphene FET Sensor with Photogating for Selective Gas Detection
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Solution Overview
Problem
Conventional graphene FETs are limited in detecting target substances and struggle to identify them through selective detection, requiring strongly charged odorant molecules and being unable to detect a wide range of gases effectively.
Innovation Solution
A graphene FET sensor element that utilizes a photogating effect by employing a first substance with changing charge conditions under light irradiation and darkness, allowing for the detection of target substances through changes in source/drain current, without requiring the odorant molecules to be strong donors or acceptors, and is capable of detecting substances in high-humidity environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional graphene FETs are used for gas detection, then the structure is simple, but the detection capability is limited and selective identification is difficult
Solution Approach 1:
The patent introduces an organic compound layer as an intermediary substance between the graphene FET and target gases. This organic compound specifically binds to target substances like 2-phenylethylamine, enabling selective detection. The organic compound acts as a mediator that enhances the interaction between graphene and specific odor molecules, solving the limitation of conventional graphene FETs that cannot effectively detect certain gases.
Solution Approach 2:
The patent creates a composite structure combining graphene with organic compounds. This composite material leverages the high electrical conductivity and sensitivity of graphene alongside the specific binding properties of organic compounds. The composite graphene-organic compound structure enables both high sensitivity and selective detection capabilities that neither material could achieve alone.
2Adaptability or versatility
If conventional graphene FETs require strongly charged odorant molecules for detection, then the detection mechanism is simple, but the range of detectable substances is limited
Solution Approach 1:
The organic compound layer serves as a mediator that facilitates detection of substances regardless of their charge strength. The organic compound specifically binds to target molecules through molecular recognition, transferring this binding information to the graphene FET as electrical signal changes. This mechanism allows detection of weakly charged or neutral molecules that conventional graphene FETs cannot detect.
Solution Approach 2:
The patent utilizes changes in electrical parameters (conductivity, carrier concentration) of graphene when organic compounds bind to target substances. By monitoring these parameter changes, the system can detect a wide variety of substances. The detection mechanism measures changes in source-drain current and gate voltage that occur when the organic compound-layer-graphene structure interacts with target gases.
3Reliability
If conventional graphene FETs are used in high-humidity environments, then the device structure remains unchanged, but detection accuracy deteriorates
Solution Approach 1:
The organic compound layer acts as a protective intermediary that shields the graphene from direct interaction with humidity while still allowing specific target molecules to bind. This intermediary layer maintains stable binding characteristics in high-humidity environments, preventing humidity from interfering with the detection mechanism while preserving the ability to detect target substances accurately.
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 element can detect a variety of target substances, including those difficult to detect with conventional graphene FETs, such as 2-phenylethylamine and DMTS, with high sensitivity and selectivity, and can distinguish between different odor components like 2-phenylethylamine and methyl benzoate, enabling real-time detection and identification.
Implementation Method 1
a first substance provided on the graphene and having a charge condition is changed when irradiation of light and stopping of the irradiation of the light are performed
Data Source
AI summary
According to one embodiment, a sensor element capable of detecting a target substance contained in an atmosphere is disclosed. The sensor includes a graphene, a drain electrode provided on the graphene, a source electrode adhered to the graphene, and a first substance provided on the graphene and having a charge condition. The charge condition is changed when irradiation of light and stopping of the irradiation of the light are performed. The target substance is detectable by measuring current that flows between the source electrode and the drain electrode. The measuring of the current is performed in a period during which the irradiation of the light and the stopping of the irradiation of the light are repeated above the sensor element.