Robot nose given keen smell sense

A layer of artificial mucus has been found to improve the ability of an "electronic nose" to precisely sniff out aromas in foods and perfumes.

Coating the accurate sensors with a mixture of polymers allowed the nose to pick out a diverse range of smells.

The synthetic mucus mimics that found in human noses and controls the rate at which different odours bombard sensors.

Electronic noses have been used for many years in the food and beverage industry for quality control.

The new enhanced nose had found smells such as bananas and milk challenging but it is now able to tell them apart.

"Our artificial mucus not only offers improved odour discrimination for electronic noses it also offers much shorter analysis times than conventional techniques," said Professor Julian Gardner of the University of Warwick and one of the team behind the work.

Smell control

Electronic noses have started to be used for a number of different applications. The US space agency Nasa has also developed an electronic nose to detect pollutants inside space craft to prevent the build up of potentially lethal concentrations.

Doctors have also started to trial the sensors to detect odours specific to diseases.

Artificial noses function in a similar way to the human olfactory but are much less sensitive and able to detect far fewer smells.

"Compared to the olfactory system, they neither mimic the complexity or the structure," said Dr James Covington of the University of Warwick. Smells consist of a number of molecules, each of which has a specific size and shape.

The human nose contains more than 100 million receptors which are able to dock with these molecules.

A layer of mucus dissolves the arriving scents and separates out different odour molecules so that they arrive at the receptors at different speeds and times. The brain is able to interpret this pattern to distinguish a diverse range of smells.

Mucus challenge

In contrast, an artificial nose consists of a much smaller array of chemical sensors, typically between six and 12, connected to a computer or neural network capable of recognising patterns of molecules.

A neural network is a collection of computer processors that function in a similar way to a simple animal brain.

As artificial noses have fewer sensors and, until now, no mucus to sieve the arriving molecules they were able to discern far fewer smells.

But the new work at the University of Warwick and Leicester University has found that applying a 10 micron (one thousandth of a centimetre) layer of a polymer inside the sensor significantly improves the performance of the nose.

"We can separate milk from cream, for example," said Dr Covington.

The team believe the enhanced electronic nose could be on sale in two years .

"We're thinking about healthcare applications to diagnose eye infections, skin diseases and urinary infections," he said.

The research is published in the journal Proceedings of the Royal Society A.

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