Dogs are smelling champions – their sense of smell is up to 10 million times more sensitive than humans. From explosives to drug trafficking, we’ve used a dog’s unique ability as a basis to develop electronic systems that can sniff out toxic gases, chemical weapons, blood alcohol levels and carbon monoxide poisoning.

With technological advancements, there is a growing interest in chemical sensors – or e-noses – in the healthcare sector. The hope is these will have a role as early diagnostics to ease the reliance on expensive tests and procedures, such as biopsies or CT scans. 

The science behind the concept is based on human metabolism, where our bodies produce chemicals known as volatile organic compounds that evaporate on the breath or are removed as other waste products. “For example, cancerous cells have a different metabolism from normal cells and therefore emit a different pattern of chemicals and a different odour,” explains Billy Boyle, co-founder of Owlstone Nanotech. While 'breathalysers' and giant mass spectrometers have been around for a number of years, pocket-sized electronic chemical sensor breathalysers specific to disease biomarkers are now being developed.

These e-noses, which are still in early development, could be used to detect a number of diseases, such as lung cancer, TB, asthma, cystic fibrosis, COPD, breast cancer, kidney and liver disease and even organ failure. The science is also being used to develop diagnostics to detect colon cancer from urine samples. And it could even be used to predict the risk of disease or an individual’s potential response to medication. “It’s very early days for this area of research. Tried and tested diagnostic techniques – scanners, biopsies and blood tests – are not being replaced just yet,” says James Gingell, science communications manager at Cancer Research UK.

But early studies are promising – research in Amsterdam found an electronic nose could detect five subgroups of asthma, which would allow for more tailored treatment, and studies in lung cancer have been found to predict the disease with 95% accuracy.

What is revolutionary about the technology is it would be cheap, hand-held, and available in doctors’ surgeries at point of care, says Peter Sterk from the University of Amsterdam. “This provides cheap technology close to the patient – and fits nicely into many other developments of having personal technology.” These factors could be particularly transformative in developing countries.

The health outcomes also speak for themselves – detecting diseases early could save lives and healthcare costs. “For the first time there is real potential for routine screening and improved rates of early diagnosis,” says Mr Boyle, adding that Owlstone is involved with the LuCID project, which aims to save 10,000 lives from lung cancer and the NHS £245 million by 2020.

There are a number of obstacles, however, including: standardising the technology; linking devices to databases and the cloud; getting independent external validation in clinical trials, which can be timely and costly; and ensuring the technology is cost-effective. The accuracy of the system could also be a sticking point – while 95% accuracy may be good enough for asthma, Prof Sterk says this is not sufficient for TB or cancer. Meanwhile, medical device regulations will also apply before any e-noses would be allowed onto the market. The other challenge, Sterk adds, is separating the good from the bad developments.

E-noses are definitely going to happen, says Mr Boyle. “There has been a lot of talk and a lot of activity over the years, but I think that sensor technology is finally catching up to the point where the promise can become a reality.”

Indeed, the first breath test for tuberculosis, which could help rapidly identify drug-resistant bacteria, has been developed, according to a paper published in the journal Nature Communications last month. TB infects 8.6 million people every year and is fatal for 1.3 million of those infected.

In the future, we could expect to see these sensors integrated with our smartphones – something Nokia has considered. And while the early models will be aimed at doctors’ surgeries, it is highly likely that in the future, these e-noses will be part of the home-monitoring kit. 

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This article was published in the October issue of PharmaTimes Magazine. You can access the digital issue here