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Measurement is core to understanding graphene according to researcher

Graphene is one of the materials that is the subject of considerable research and has the potential to be used in a variety of applications. One of the major applications of the material could be in computer CPUs.

Researchers say that the properties of graphene could allow the construction of computer processors that run at 1000GHz frequencies. The material also has potential applications in sensing instruments, chemical sensors, and other biosensors thanks to its low capacitance, which makes a very low signal to noise ratio.

Researcher N.J. Tao from the Biodesign Institute at Arizona State University says that graphene is comprised of a two-dimensional honeycomb structure of carbon atoms and is very strong and versatile. According to Tao, graphene is roughly 200 times stronger than steel and is very light. A sheet of graphene one atom thick and large enough to cover an entire football field would weigh under a gram.

The excitement about graphene isn’t about its strength of lightweight nature, but about its unusual electronic properties. The Biodesign Institute at Arizona State University explains that graphene has a unique and outstanding ability to allow electricity to flow through its material with little impedance.

Tao has been able to measure the quantum capacitance of graphene, which he stresses is an essential part of understanding  of graphene and its use in microprocessors and other applications. The quantum capacitance of a material is the result of the Pauli exclusion principal that states two fermions can't occupy the same location at the same time. That means that when one quantum state inside graphene is filled, fermions are forced to occupy successively higher energy states.

Tao explains the process, "it’s just like in a building, where people are forced to go to the second floor once the first level is occupied."

Tao's study placed two electrodes on to a graphene structure and voltage was applied across the materials two-dimensional surface with a third gate electrode. The ability of graphene to store charge according to the laws of quantum capacitance were directly measured and did not conform to predictions of the behavior of graphene.

One possible future use for graphene in biosensor applications involves putting antibodies onto the surface of graphene to study the interaction of the antibodies with specific antigens. The sensor would be able to detect individual binding events given a suitable sample. The material could also be used in the future as an ultracapacitor to store massive amounts of energy form solar or wind power plants.

Tao said, "You can imagine an atomic sheet, cut into different shapes to create different device properties."




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