Science: No business like nose business: Susan Watts on a chemist who believes in the romantic and healing uses of smell

If George Dodd has his way, singles parties will never be the same. Dr Dodd studies smells, and dreams of building a pocket 'nose' to help guests sniff out others with compatible body odours.

The device would take the hit and miss out of the search for a partner by tuning into the 'smellprints' of those in the room, picking up the hormones of attraction - pheromones - and alerting its owner to the mixture most likely to appeal.

This is the stuff of fantasy for now, but Dr Dodd is determined to put the science of smells to work. As a chemistry lecturer at the University of Warwick and director of its Institute of Olfactory Research, Dr Dodd has been personally responsible for a string of commercial spin-offs.

Smell, he says, is the most underrated of senses: 'The vast bulk of what we call our sense of taste is in fact smell.' He suggests a simple test for sceptics. 'Next time you are in a restaurant, order a bowl of fine french onion soup, but hold your nose well before it arrives. Once it is in front of you, taste the soup and all you will detect is that it is hot, wet and salty.'

'The onion flavours will only become apparent as you release your grip. This allows the soup vapours to waft into your nostrils and flow up from the back of your mouth through the linking canal that leads to the nose.' He describes three independent sets of chemical sensors involved in detecting the onion aroma.

The first is the severely limited sense of taste, located exclusively on the tongue. The second is the sense of smell, far up inside the nose, and the third the trigeminal sense, the least known of all senses.

Some of the most powerful 'smells' possess only a barely detectable aroma. Human pheromones are an example. Their perceptible smell is mild, but their attractive lure is famous. Certain foods with mythical notoriety as aphrodisiacs are known to contain the same pheromones as humans, including oysters, caviar and certain wines.

Dr Dodd, in collaboration with a London company called Interactive Fragrance Technologies, has developed a pounds 30 pack containing a human pheromone for sexual attraction. Ten drops, added to perfume, should do the trick, the company claims.

This product, 'Pheromone Factor', will soon be available on mail order, with another, called 'Nature's Tranquilliser', following close behind. This is a laboratory recreation of the smell of the skin of a woman who has just given birth - a sort of 'essence of mother', Dr Dodd explains. Virgin Airlines has bought 50,000 sachets for gifts to first-class passengers.

The soothing aroma, named Osmone 1, is being sold as an alternative to tranquillisers. Dr Dodd claims a few sniffs a day is enough to evoke the feelings of comfort and reassurance experienced when newborn babies are in their mothers' arms. Each pounds 9.99 pack lasts about three months.

Dr Dodd's other main commercial excursion has been the development of the artificial nose. In collaboration with Neotronics, a Hertfordshire-based company, he has produced an electronic nose, which he claims can outsniff the most sensitive analytical equipment, yet costs half as much.

The company believes its pounds 20,000 Neotronics Olfactory Sensory Equipment (Nose) is a world first, and is anticipating commercial interest from a wide range of companies. One of its earliest uses has been in sniffing and discerning aromas and vapours for food and drinks manufacturers.

It is a simple task to teach the nose to spot the difference between white wine and champagne. It can be trained to identify the smell of fresh crisps and reject batches that fall below par. The nose can distinguish fake perfume from the real thing, and separate young cheeses, wines and spirits from those that have matured.

Neotronics is talking to a range of household names interested in using the nose, including Weetabix, Coca-Cola, Pedigree Pet Foods and Walkers crisps.

Early research with Bass, the brewers, already holds commercial promise. The nose is used to detect a chemical in beer called diacetyl, which can be produced during fermentation and give beer an unpleasant buttery taste. Just one molecule in a million of this chemical is enough to ruin the taste.

Dr Dodd's fake nose is the culmination of more than 30 years' research into its human counterpart - one of the most complex of our sensory organs. Noses are remarkably perceptive - capable of detecting only a handful of molecules diluted in air a million million times. We instantly recognise the smell of coffee, even though it contains 670 different types of smelly molecules. This skill is thought to be the result of repeated exposure to the smells around us, fine tuning our ability to recognise them.

Like the human version, the electronic nose has all the apparatus it needs to recognise hundreds of distinct smells, but it must first be taught to spot these by being presented with samples.

Dr Dodd describes the sense of smell as 'a shape-sorting exercise'. The artificial nose mimics in electronics the functions of its human counterpart, using an array of twelve sensors instead of the 10,000 or so in the human nose.

Each sensor consists of a tiny patch of polymers, long-chained molecules, the width of a human hair. The patches are designed with gaps, shaped so that key smell molecules will slip in and fill them. The smell molecules alter the ability of the polymer to conduct electricity. The pattern of gaps filled or left empty on each sensor, and the corresponding amount of electricity each sensor conducts, becomes the smell fingerprint of the sample.

Computer software plays the role of the human brain, comparing this smell fingerprint with known patterns stored in its memory. If it finds a match, the nose 'recognises' the smell image.

But Dr Dodd's plans lie elsewhere. He intends to dedicate the next 10 years to what he calls 'body odour imaging'. He is optimistic that by using the nose to smell people's breath he can open up a new discipline of non-invasive clinical diagnosis. He has developed a system now in use in Gambia to identify people with gastritis.

His ultimate dream is to develop a system capable of reading the smell fingerprint of lung cancer, Britain's biggest killer among cancers. He says that several published studies suggest that the breath of people with lung cancer contains chemicals that might form a pattern the electronic nose can recognise.

(Photograph omitted)