Scientists create world's tiniest light-powered engine

British researchers said Monday they have developed the world's tiniest engine -- just a few billionths of a meter in size -- which uses light to power itself.

The nanoscale engine, published in the U.S. journal Proceedings of the National Academy of Sciences, could form the basis of future nano-machines that can navigate in water, sense the environment around them, or even enter living cells to fight disease, researchers at the University of Cambridge said.

The prototype device is made of tiny charged particles of gold, bound together with temperature-responsive polymers in the form of a gel.

When the nano-engine is heated to a certain temperature with a laser, it stores large amounts of elastic energy in a fraction of a second, as the polymer coatings expel all the water from the gel and collapse, forcing the gold nanoparticles to bind together into tight clusters.

But when the device is cooled, the polymers take on water and expand, and the gold nanoparticles are strongly and quickly pushed apart, like a spring.

The research suggested how to turn Van de Waals energy -- the attraction between atoms and molecules -- into elastic energy of polymers and release it very quickly.

"The whole process is like a nano-spring," said Professor Jeremy Baumberg from Cambridge's Cavendish Laboratory, who led the research.

"The smart part here is we make use of Van de Waals attraction of heavy metal particles to set the springs (polymers) and water molecules to release them, which is very reversible and reproducible."

Baumberg named the devices ANTs, or actuating nano-transducers.

"Like real ants, they produce large forces for their weight. The challenge we now face is how to control that force for nano-machinery applications," Baumberg added. Endit