Electronic noses hold out the promise of sniffing out criminals

There has been CCTV, finger printing and eye recognition. Now comes body odour profiling. In its ongoing efforts to nail the bad guys, the US Department of Homeland Security is investing heavily in the sniff test: "odourprint".

Plans have quietly appeared on the American government website to announce some serious funding of a study looking at the potential of using people's individual smell to identify criminals and to uncover when they are lying.

There are scientists who claim our smell is just as unique as our DNA, and the work to be funded will look into the chemical nature of the human scent as utilised by crime fighters in the form of the bloodhound. Dogs have clued the scientists into the possibilities of smell technology although their accuracy has been shown to be as low as 85%, with an untrained dog doing no better pure chance.

But now efforts and research is under way to make the scrutiny of smell more exact. Tests have shown that mothers can pick out their babies by smell alone, while humans can be shown to recognise each other through the tang of their armpit BO. The smell of a human has also been shown to vary by gender and by age - one recent study claimed that men smell like cheese while women smell of grapefruit or onions.

There may even be racial differences: Asians, for example, have fewer apocrine sweat glands than black or white people. In a new book about scent called Headspace, Amber Marks reports that in the 1990s a British electronic-nose company was approached by the South African police and asked for the "odour signature" of black people. The company refused.

The electronic nose is being developed widely and last year biological engineers found a way to mass-produce smell receptors in the laboratory, an advance that paves the way for "artificial noses". "Smell is perhaps one of the oldest and most primitive senses, but nobody really understands how it works. It still remains a tantalising enigma," said Shuguang Zhang of MIT, author of a paper on the work in the Proceedings of the National Academy of Sciences.