Nanosprings in their step

A team of Clemson University researchers led by Apparao Rao, a professor of physics, has invented a way to make beds of tiny, shock-absorbing carbon springs that could be used to protect delicate objects from damaging impacts.

With collaborators at the University of California at San Diego (UCSD), the team has shown that layers of these tiny coiled carbon nanotubes can act as extremely resilient shock absorbers.

Similar coiled carbon nanotubes have been made before, yet Clemson researchers say this method is unique since beds of coiled carbon nanotubes can be grown in a single step using a proprietary hydrocarbon-catalyst mixture.

The group also envisions coiled nanotubes in soldiers’ body armour, car bumpers and bushings and even as cushioning elements in shoe soles.

Rao said: 'The problem we have faced in the past is producing enough of these coiled carbon nanotubes at a reasonable cost.

'Because our current method produces coiled nanotubes quickly in high yield, it can be readily scaled up to industrial levels. After formation, the coiled nanotubes can be peeled off in one piece and placed on other surfaces to form instant cushioning coatings.'

In earlier studies, Rao and his team, along with UCSD collaborators, tested more conventional straight carbon nanotubes against coil-shaped nanotubes. When a stainless steel ball was dropped onto a single nanotube layer, the coiled nanotubes completely recovered from the impact, while the straight ones did not.

In previous work, Rao’s group developed a process that coaxes a traditionally straight carbon nanotube to split into a 'Y' shape when a voltage is applied to it.