Nanostructure research serves security and medical sectors

According to the UK, Belgian and US research groups, the new nanosensors could also be used to detect the presence of particular molecules or proteins in patients' blood samples, with high sensitivity. The nanostructures are each about 500 times smaller than the width of a human hair. One is shaped like a flat circular disk while the other looks like a doughnut with a hole in the middle. When brought together they interact with light very differently to the way they behave on their own. The team, led by Imperial College London physicists, discovered that by putting together two nanostructures made of gold and silver, they could make an early prototype device that, once optimised, exhibited an ability to detect particular chemicals in the immediate surroundings. The nanostructures, when paired together, scattered specific colours within white light much less, leading to an increased amount of light passing through the structure undisturbed. The research team realised that this was different to how both structures scattered light separately. This decrease in the interaction with light was in turn affected by the composition of molecules in close proximity to the structures. Prof Stefan Maier from Imperial's department of physics, hopes that this effect can now be harnessed to produce sensor devices. He explained: "Pairing up these structures has a unique effect on the way they scatter light – an effect which could be very useful if, as our computer simulations suggest, it is extremely sensitive to changes in surrounding environment. With further testing we hope to show that it is possible to harness this property to make a highly sensitive nanosensor." Although metal nanostructures have been used as sensors before, this is the first time a pair with such a carefully tailored interaction with light has been created.