Optical dog's nose to detect diseases

Researchers from the University of Adelaide are developing an instrument they equate to an ‘optical dog’s nose’, which uses a special laser to measure the molecular content of a sample of gas. Their work has been detailed in the journal Optics Express.

Lead researcher Dr James Anstie, ARC Research Fellow with the university’s Institute for Photonics and Advanced Sensing (IPAS), said the aim of the device is to replicate the effect of a dog detecting disease through the smell of its owner’s breath. “We think that dogs are great,” said Dr Anstie, “but they’re not as easy to tame as light, and so what we want to do is use light in place of a dog’s nose to detect the molecules out in your breath and also to figure out what’s going on inside.”

The system uses a specialised laser — an optical frequency comb — that sends up to a million different light frequencies through the sample in parallel. Dr Anstie said the light ‘senses’ the range of molecules that are present in the sample, each of which absorbs the light at different optical frequencies and therefore has a unique molecular fingerprint.

“Those molecules are by-products of metabolic processes in the body,” said Dr Anstie, “and their levels change when things go wrong. There have been good studies undertaken around the world which show that diseases like lung and oesophageal cancer, asthma and diabetes can be detected in this way, even before external symptoms are showing.”

The system is fast, non-invasive, highly sensitive and has the ability to test for — and detect concentrations of — a range of molecules in a sample all at once. Dr Anstie said, “The next step is to work out how to accurately sample and interpret the levels, which will naturally vary from person to person.”

Dr Anstie believes the group will approach part-per-million sensitivity within the next few months, have a working prototype in 2-3 years and hopefully release a commercial ‘plug and play’ product in 3-5 years. Other potential applications for the device include measuring trace gases, such as atmospheric carbon dioxide, and detecting impurities in natural gas streams.

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