Single nanowire shrinks spectrometer

In use, the single nanowire could be used in potential applications such as assessing the freshness of foods, the quality of drugs, or identify counterfeit objects, all from a smartphone camera. Details are reported in Science.

Most spectrometers are based around the spatial separation of light into different spectral components, which limits their size and makes it difficult to shrink to sizes much smaller than a coin. Now, Cambridge University researchers have overcome this challenge to produce a system up to a thousand times smaller than those previously reported.

The Cambridge team, working with colleagues from the UK, China and Finland, used a nanowire whose material composition is varied along its length, enabling it to be responsive to different colours of light across the visible spectrum. Using techniques similar to those used for the manufacture of computer chips, they then created a series of light-responsive sections on this nanowire.

"We engineered a nanowire that allows us to get rid of the dispersive elements, like a prism, producing a far simpler, ultra-miniaturised system than conventional spectrometers can allow," said first author Zongyin Yang from the Cambridge Graphene Centre. "The individual responses we get from the nanowire sections can then be directly fed into a computer algorithm to reconstruct the incident light spectrum."