14 January 2013

Graphene Plasmonics Lead To Development of Molecular Sensitive Sensing Devices

Plasmonic nanostructures coupled with graphene
A device that can see one molecule though a simple optical system and can analyse its components has been developed through the technology of graphene and plasmonics; graphene plasmonics.

Rapid oscillations of the electron density in conducting media such as plasma or metals result in plasma oscillations. These waves of electrons are called plasmons. Plasmonics is the study of how to use these plasmons in applications such as transmission of data and information.

Graphene possess plasmons that are both tunable and adjustable.

Graphene plasmonics takes advantage of the electronic properties of graphene combined with optical properties of plasmonic metamaterials to create new and advanced applications.

Two main directions on graphene plasmonics are in graphene phtovoltaics and optical plasmonic systems. With graphene photovoltaics, plasmons can be used to modify the opto-electronic properties of graphene for fast photo-detectors and effective photocells.

With optical plasmonic systems, graphene can be used to manipulate the optical properties which may lead to the development of inexpensive, fast and small active optical elements.

Writing in Nature Materials, the scientists, working with colleagues from Aix-Marseille University, have created a device which potentially can see one molecule though a simple optical system and can analyse its components within minutes. This uses plasmonics – the study of vibrations of electrons in different materials.

The breakthrough could allow for rapid and more accurate drug testing for professional athletes as it could detect the presence of even trace amounts of a substance.

It could also be used at airports or other high-security locations to prevent would-be terrorists from concealing explosives or traffickers from smuggling drugs. Another possible use could be detecting viruses people might be suffering from.

Graphene, isolated for the first time at The University of Manchester in 2004, has the potential to revolutionise diverse applications from smartphones and ultrafast broadband to drug delivery and computer chips.

It has the potential to replace existing materials, such as silicon, but University of Manchester researchers believe it could truly find its place with new devices and materials yet to be invented.

Video: Manipulating light with graphene

The researchers, lead by Dr Sasha Grigorenko, suggested a new type of sensing devices: artificial materials with topological darkness. The devices show extremely high response to an attachment of just one relatively small molecule. This high sensitivity relies on topological properties of light phase.

To test their devices, researches covered them with graphene. They then introduced hydrogen onto the graphene, which allowed them to calibrate their devices with far superior sensitivity than with any other material.

Testing for toxins or drugs could be done using a simple blood test, with highly-accurate results in minutes. The researchers found that the sensitivity of their devices is three orders of magnitude better than that of existing models.

The academics, from the School of Physics and Astronomy, hope the research will show the practical applications from an emerging area of research – singular optics.

Dr Grigorenko said: "The whole idea of this device is to see single molecules, and really see them, under a simple optical system, say a microscope.

"The singular optics which utilize the unusual phase properties of light is a big and emerging field of research, and we have shown how it can have practical applications which could be of great benefit.

"Graphene was one of the best materials we could have used to measure the sensitivity of these molecules. It is so easy to put the hydrogen on to it in controlled way.

"We are only starting to scratch the surface of what this research might tell us but it could have profound implications for drug detection, security and viruses."


University of Manchester
Nature Materials
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