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Saturday, 2 June, 2001, 02:01 GMT 03:01 UK
New nanowires could track tiny explosives
A paramilitary force soldier walks past a blasted military in India
Tiny wires will help prevent bomb attacks
By science correspondent Andrew Craig

Chemists in California say they have developed tiny wires that can detect very small amounts of explosives.

They hope that the technology will provide a tool both to prevent bomb attacks, and to detect old unexploded weapons.

The team from the University of California at San Diego describe their new polymer as a nanowire.

It is 2,000 times thinner than a human hair, and consists of a string of silicon atoms surrounded by organic molecules.

When an ultraviolet light is shone on the material, it becomes luminous.

But any trace of the explosive TNT - or of picric acid, which is also used in bombs - short-circuits the effect, and stops it glowing.

Instant result

The researchers, writing in the German journal Angewandte Chemie, say the material could be particularly useful because it is stable in air and water.

The nanowires can even be dissolved in paint, or sprayed on to filter paper.

They can then detect explosive traces in the air or water that surrounds them - or on the hands or clothes of a suspect.

And they give an instant result, without the need for laboratory tests.

Members of the team also foresee a use for their invention in finding unexploded bombs and mines left over from wars, which may have TNT leaking out of them into the earth or the sea.

Levels can be detected even when they are as low as one part per billion in air, and 50 parts per billion in seawater.

The material has yet to go into production, but samples are being tested by the FBI and the US Marines.

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