A team of scientists has created a material that is thousands of times thinner than a sheet of paper, and is strong enough to maintain its shape even after being bent.

The tiny plates, made of aluminium oxide, are the first of their kind that can be manipulated by hand despite their nanoscale thinness.

A material of this strength and size could have applications in aviation, and even spur the development of insect-inspired flying robots.

A team of scientists has created a material that is thousands of times thinner than a sheet of paper, and is strong enough to maintain its shape even after being bent. The tiny plates, made of aluminium oxide, are the first of their kind that can be manipulated by hand despite their nanoscale thinness

TINY ALUMINIUM OXIDE PLATES Scientists from the University of Pennsylvania have created a material that is thousands of times thinner than a sheet of paper. The material, made of aluminium oxide, is strong enough to maintain its shape even after being bent. It is the first material this small that can be manipulated by hand. Scientists have been working for years to design the thinnest, lightest material possible that is as strong as something of its size can be. Such a material would be useful in aviation, which demands lightness. Advertisement

Scientists have been working for years to design the thinnest, lightest material possible that is as strong as something of its size can be.

Now, researchers at the University of Pennsylvania have created just that.

'Materials on the nanoscale are often much stronger than you'd expect, but they can be hard to use on the macroscale,' says Igor Bargatin, Class of 1965 Term Assistant Professor of Mechanical Engineering and Applied Mechanics in Penn's School of Engineering and Applied Science, who led the study.

'We've essentially created a freestanding plate that has nanoscale thickness but is big enough to be handled by hand. That hasn't been done before.'

Normally, an object of such thinness will lose its original shape after being bent and twisted.

Graphene, a Nobel Prize winning material which can be as thin as a single carbon atom, must be stretched on a canvas in a frame in order to prevent curling.

This design, however, can return to its shape without any outside help.

'The problem is that frames are heavy, making it impossible to use the intrinsically low weight of these ultra-thin films,' Bargatin says.

'Our idea was to use corrugation instead of a frame.

'That means the structures we make are no longer completely planar, instead, they have a three-dimensional shape that looks like a honeycomb, but they are flat and contiguous and completely freestanding.'

'It's like an egg carton, but on the nanoscale,' added Prashant Purohit, an associate professor of mechanical engineering who also led the study.

Scientists have been working for years to design the thinnest, lightest material possible that is as strong as something of its size can be. Now, researchers have created just that. A material of this strength and size could have applications in aviation, and even spur the development of insect-inspired flying robots

The aluminium oxide plates are between 25 and 100 nanometers thick, and are stacked one atomic layer at a time.

Aluminium oxide, Bargatin explains, is actually a ceramic, which one would expect to crack easily. To the researchers' surprise, it did not crack.

'The plates bend, twist, deform, and recover their shape in such a way that you would think they are made out of plastic,' Bargatin says.

'The first time we saw it, I could hardly believe it.'

The honeycomb structure of the plates makes the material stiffer, preventing it from folding upon itself or getting stuck to something else. While a crack is possible, the structure prevents it from running all the way across.

'If a crack appears in our plates, however, it doesn't go all the way through the structure,' says Keivan Davami, a postdoctoral scholar who also led the study.

'It usually stops when it gets to one of the vertical walls of the corrugation.'

An insect wing is only a few microns thick, one researcher says, limited in size only by the thickness of cells.

This material, which weighs as little as a tenth of a gram per square meter, is up to ten times thinner than the thinnest man-made wing material.