An innovative graphene sensor capable to detect explosive gases ten times more effectively than any device on sale was created at the labs of the American Rensselaer Polytechnic Institute, in co-operation with the Chinese Shenyang National Laboratory for Materials Science.
Several studies had already demonstrated that individual nanostructures (e.g. nanotubes or graphene sheets) are extremely sensitive to a variety of gases. However, the tiny size of such elements made it almost impossible to create a true detector.
The new system, conceived by Professor Nikhil Koratkar alongside his colleague Hui-Ming Cheng, managed to overcome this barrier. How? The researchers produced a larger graphene structure using a sort of nickel sponge. They “grew” graphene on the metal surface and, once their goal was achieved, removed the nickel frame, thus obtaining a three-dimensional, strong and flexible graphene lattice – roughly as large as a post stamp – ideal to resist to time wear.
Despite its size, this graphene foam (as it is called) behaves just like an individual nanostructure: it is, in fact, a seamless, continuous complex, where electrons can move freely without resistance.
The sensor absorbs the gases easily (in the tests ammonia and nitrogen dioxide were used as the by-products of a number of explosives), and changes its electric resistance, highlighting any hazards in a simple, cheap, and much more accurate way compared to any devices available to date. The achieved results are consistent, repeatable, and very promising.
Lastly, the structure is extremely easy to clean: applying a 100 mA current (quite strong) is enough to eliminate all the absorbed compounds. This process does not alter the functionality of the system, and makes it completely reversible.
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The Editorial Staff
Published on Tuesday, March 26, 2013