By Rebecca Morelle
Electronically tagging passengers at airports could help the fight against terrorism, scientists have said.
The tag would track passengers' movements
The prototype technology is to be tested at an airport in Hungary, and could, if successful, become a reality "in two years".
The work is being carried out at a new research centre, based at University College London, set up to find technological solutions to crime.
Other projects include scanners for explosives and dirty bomb radiation.
Dr Paul Brennan, an electrical engineer, is leading the tagging project, known as Optag.
He said: "The basic idea is that airports could be fitted with a network of combined panoramic cameras and RFID (radio frequency ID) tag readers, which would monitor the movements of people around the various terminal buildings."
The plan, he said, would be for each passenger to be issued with a tag at check-in.
He said: "In our system, the location can be detected to an accuracy of 1m, and video and tag data could be merged to give a powerful surveillance capability."
The tags do not store any data, but emit a signal containing a unique ID which could be cross-referenced with passenger identification information. In the future, added Dr Brennan, this could incorporate biometric data.
The project still needs to overcome some hurdles, such as finding a way of ensuring the tags cannot be switched between passengers or removed without notification.
The issue of infringement of civil liberties will also be key.
But potentially, said Dr Brennan, the tags could aid security by allowing airports to track the movement patterns of passengers deemed to be suspicious and prevent them from entering restricted areas.
It could also aid airports by helping evacuation in case of a fire, rapidly locating children, and finding passengers who are late to arrive at the gate.
The "proof of concept" of the system is about to be tested at Debrecen airport in Hungary. If successful, claimed Dr Brennan, it could be available elsewhere within two years.
The new centre will also be investigating a range of other airport security tools.
Professor Robert Speller has been developing scanners to detect explosives and drugs. The devices could be used at airports or other ports of entry.
The scanners work by firing an x-ray at an item and then detecting how light particles called photons are scattered.
A reader would detect where the passengers were located
Different materials, he said, produce unique patterns of photon scattering, and this can be used to identify whether an explosive or type of drug is present. The scanners, he said, could be incorporated into the machines being used by airports to scan bags.
He is also developing a prototype "Compton camera".
This portable device, he said, could be used if a suspected dirty bomb had been exploded. It is able to detect if any radiation is present, and if so, its precise location.
He said it would help the emergency services identify dangerous areas, and would aid the possible clear-up operation.
The UCL Centre for Security and Crime Science, which opens on Friday, works across many different areas in science and is investigating a number of security and crime issues.
Professor Gloria Laycock, director of the centre, said: "Security is a major issue in today's society and can take many forms.
"We've got rising crime across the developing world, and that has been linked to rising opportunities for crime. The most effective means of tackling this is by tackling those opportunities. Science and technology can help us to do this."