Hypersensitively sensing

Researchers at the University of Manchester have developed graphene-based sensors that can detect a single molecule of a toxic gas.



Graphene is a one atom-thick gauze of carbon atoms that resembles chicken wire. The scientists have found that the material, which they had thought was chemically inert, is actually extremely sensitive to the presence of tiny amounts of gases, such as alcohol vapour, or extremely toxic carbon monoxides.



The scientists envisaged the sensors being eventually used to detect hidden explosives at airports and carbon monoxide in homes.



The researchers claim to have demonstrated that graphene-based sensors allow individual events to be registered when gas molecules attach to the surface. The gas molecules attach to graphene without disrupting the chicken wire structure and cause notable changes in the material’s electrical conductivity by adding or taking away electrons.



‘This level of sensitivity is typically millions of times higher than for any other gas detector demonstrated before,’ said Dr Kostya Novoselov from the School of Physics and Astronomy at Manchester. ‘Graphene sensors are as sensitive as sensors can be in principle.’



According to the researchers, graphene-based gas detectors could be commercially produced using epitaxial graphene wafers, which is already available on the market. However, the detectors are not yet able to distinguish between individual gases.



‘At present you could not sniff out a flammable substance hidden in luggage because an increase in air humidity would give false readings,’ said Prof Andre Geim, who worked on the project.



‘But this is exactly the same problem that all solid-state gas detectors have encountered, and it can be successfully solved through various detection schemes including filters and analysis of a temperature response. We see no reason why the same cannot be done successfully with graphene.’



Researchers from the Institute for Microelectronics Technology in Russia and the Institute for Molecules and Materials at the University of Nijmegen in the Netherlands also collaborated on the project.