dailymail - A device that smells human fear is being developed by British scientists and could soon be sniffing out anxious terrorists.
The technology relies on recognising a pheromone - or scent signal - produced in sweat when a person is scared.
Researchers hope the 'fear detector' will make it possible to identify individuals at check points who are up to no good.
Terrorists with murder in mind, drug smugglers, or criminals on the run are likely to be very fearful of being discovered.
However calm they might appear on the surface, their bodies could give them away.
Although the research is at an early stage, the aim is to develop a prototype device in the next two to three years.
Evidence that the smell of fear is real was uncovered by US scientists last year who studied the underarm secretions of 20 terrified novice skydivers.
The researchers found that people appear to respond unconsciously to the sweat smell of a frightened person.
Scientists at City University London now hope to develop security sensor systems that can detect the human fear pheromone.
Team leader Professor Tong Tun told The Engineer magazine: 'The challenge lies in the characterisation and identification of the specific chemical that gives away the signature of human fear, especially the fear in relation to criminal acts.'
The project will look at potential obstacles to reliable detection such as the effects of perfume, and natural differences between individuals.
If the initial 18-month feasibility study is successful, the first detectors could be developed in the next two to three years, said Prof Tun.
She added: 'I do not see any particular reason why similar sensor techniques cannot be expanded to identify human smells by race, age or gender to build a profile of a criminal during or after an incident.'
In the US study, scientists at Stony Brook University in New York State used taped absorbent pads to soak up sweat from the skydivers' armpits just before they made their first tandem jump.
Other volunteers, who were not told the true nature of the experiment, were later asked to sniff the samples through a nebuliser. At the same time, their brains were scanned.
The study showed that the scent of sweat from the scared skydivers triggered a heightened response in brain regions associated with fear.
But sweat samples taken from the skydivers as they ran on a treadmill - with their feet safely on the ground - did not have the same effect.
Animals are known to produce 'alarm pheromones' to alert each other to danger.