Blast-proof curtain that gets thicker when it is stretched to be used to protect terror targets

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A new type of blast-proof curtain that gets thicker rather than thinner when stretched is being developed to protect potential terrorist targets.

The new curtain remains intact and captures debris such as flying glass when windows are blown in.

The project is primarily designed to be fixed over the windows of potential terrorist targets, such as Government and high-profile commercial properties.

Professor Ken Evans, at the University of Exeter, who is leading the project, said: 'In the 1995 Oklahoma City bombing, glass accounted for nearly two thirds of all eye and head injuries.

'The blast curtain we're working on, which will be capable of dispersing the shock from an explosion extremely effectively, will be backed up by robust scientific understanding vital to ensuring it really can block flying debris and achieve widespread use.'

Potential uses could also include protecting people in buildings from the effects of severe weather events such as typhoons and hurricanes, the university said.

The new curtain aims to remove the need for anti-shatter films by using stronger, more resilient fibres woven into a carefully controlled textile structure.

The secret lies in the yarn the curtain is made from, the university said. The yarn is an ‘auxetic’ material – one that gets thicker when stretched.

A stretchy fibre provides the core of the yarn and a stiffer fibre is then wound around it.

When the stiffer fibre is put under strain, it straightens, causing the stretchy fibre to bulge out sideways - increasing the yarn's diameter.

As well as thickening, small pores open up in the fibres when they are stretched.

These pores are designed to let through some of an explosion's shock wave, ensuring it doesn't rip.

At just 1-2mm thick, the new type of curtain can also be designed to let in a reasonable amount of natural light. It is currently being tested in situations similar to car bomb explosions.

Testing at a Government-approved facility has already started, and after rigorous certification procedures, the new curtain could be on the market within three to five years.

Researchers also believe that the technology could have applications in other fields, including 'self-healing' bandages.

Wounds that swell would put the bandage under tension opening up pores that are impregnated with an antibiotic which would then be released.

It could also be used to manufacture dental floss that expands when you pull it, to fill in gaps to make cleaning more effective for teeth.