Nanotechnology researchers headed by a team from Cambridge University have developed a spectrometer made from a single nanowire; a breakthrough with wide ranging applications. In fact, the new sensor is so small it could be inserted into the camera on a mobile phone or similar handheld device. This would allow for ‘on-the-go’ testing of pharmaceutical drug quality, food freshness, or even in identifying counterfeit objects; real-world usage of nanowires that the team expect could be on the market within five years.

The impact of this discovery could be even more powerful, not only for the nanowire industry, but for science and technology in general. As the Cambridge University press release, outlines, “In the 17th century, Isaac Newton, through his observations on the splitting of light by a prism, sowed the seeds for a new field of science studying the interactions between light and matter – spectroscopy. Today, optical spectrometers are essential tools in industry and almost all fields of scientific research. Through analysing the characteristics of light, spectrometers can tell us about the processes within galactic nebulae, millions of light years away, down to the characteristics of protein molecules.”

The researchers were inspired towards this advance when they looked at the innate problems with current spectrometer appliances. As the industry journal Nano Magazine explains, “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.”

By using nanowires to overcome the spatial problems, the team believe that spectrometers could be made as much as 1000 times smaller than the currently available bulky and complex machines.

As the journal describes, “Cambridge University researchers, working with colleagues from the UK, China and Finland, have produced 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.”

The team have now published their findings in the journal Science, where they announced the creation of, “… a microspectrometer based on a single, compositionally engineered nanowire. This result is a practical step forward for the use of other light-sensitive nanomaterials for such ultra-miniaturized spectroscopy platforms.” Adding that, “[These] devices are capable of accurate, visible-range monochromatic and broadband light reconstruction, as well as spectral imaging from centimeter-scale focal planes down to lensless, single-cell–scale in situ mapping.”

“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,” says Zongyin Yangfrom the Cambridge Graphene Centre, and the study’s first author. “The individual responses we get from the nanowire sections can then be directly fed into a computer algorithm to reconstruct the incident light spectrum.”

“When you take a photograph, the information stored in pixels is generally limited to just three components – red, green, and blue,” explains co-first author Tom Albrow-Owen. “With our device, every pixel contains data points from across the visible spectrum, so we can acquire detailed information far beyond the colours which our eyes can perceive. This can tell us, for instance, about chemical processes occurring in the frame of the image.”

The industry journal AZoNano, is quick to note the invention’s potential, writing that, “One of the most promising uses of the nanowire could be in biology. Since the device is so tiny, it can directly image single cells without the need for a microscope. And unlike other bioimaging techniques, the information obtained by the nanowire spectrometer contains a detailed analysis of the chemical fingerprint of each pixel.”

Meanwhile, the researchers themselves see how the platform could be developed to function across the entire spectrum, with, “an entirely new generation of ultra-compact spectrometers working from the ultraviolet to the infrared range.” Making them a practical solution for lab-on-a-chip systems, in smart wearable devices, in biological implants, or other as yet unthought of consumer, research, and industrial applications. They can be used in everyday situations where chemical processes are at work, such as in a supermarket where food is naturally, yet invisibly, decomposing.

With patents still pending, the nanotechnology industry will have to wait until this discovery is applied inside devices before production can begin. But what the advance reiterates, is the ever-increasing influence that nanotechnology products, such as nanowires, graphene, and carbon nanotubes have over the way we will live and the products we will use in the future.

As Dr Tawfique Hasan, who led the study, states, “Our approach [with nanowires] could allow unprecedented miniaturisation of spectroscopic devices, to an extent that could see them incorporated directly into smartphones, bringing powerful analytical technologies from the lab to the palm of our hands.”

Photo credit: Cambridge University, Dynamicsystems, Venturebeat, & Iopscience