Graphene Field Effect Transistors For Chemical Sensing

Graphene Field Effect Transistors For Chemical Sensing - Featured Sensors
Figure: Sensitivity of to various gases (Sens. Actuators B 163(1), 107–114 (2012)).

Graphene produced with chemical vapor deposition (CVD) will form the cornerstone of future graphene-based chemical, biological, and other types of sensors. The 2D nature of the material provides intrinsic advantages for sensing applications, because the entire material volume acts as a sensing surface. Furthermore, graphene provides excellent mechanical strength, thermal and electrical conductivity, compactness, and potentially low cost, which is necessary for competing on the crowded sensor market.

Graphene-based gas/vapor sensors have attracted much attention in recent years due to their variety of structures, unique sensing performance, room-temperature working conditions, and tremendous application prospects. Apart from water vapor, graphene has been used to sense gases such as NH3, NO2, H2, CO, SO2, H2S, as well as vapor of volatile organic compounds, resulting in a dramatic rise in scientific publication numbers on this topic. Graphene has also been used to detect traces of opioids in concentrations as low as 10 picograms per milliliter of liquid.

The most simple and common configuration for graphene-based sensors is the graphene field-effect transistor (GFET), a sheet of graphene with a sensing area between two metal contacts. The carrier mobility can be tuned using the electric field effect with a back gate, yielding tunable sensitivity. Such a device was shown to have even single molecule detection capability (Nat. Mater. 6(9), 652–655 (2007)). The detection and working principle of GFET chemical sensors are also very simple: the electrical resistance of the device changes when something attaches to the graphene. Certain gases have shown up to 15% change in resistance, with others like methanol showing an easily detectable change of ~5% (see figure below).

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Source: Graphenea

Graphene Field Effect Transistors For Chemical Sensing - Featured Sensors
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