World's Tiniest Engine Is Nanoscale Device Made Of Tiny Charged Gold Particles

The tiniest engine in the world, just a few billionths of a meter in size has been created by a team of researchers from the University of Cambridge. The nanoscale engine can power itself with light and also use the framework for many nano-machines in the future, such as entering living cells to combat illnesses and navigate water.

Made of tiny charged gold particles that are bound with temperature-responsive polymer gels, the engine's temperature rises and stores large amounts of elastic energy as the polymer coating releases water and shatters.

The gold nanoparticles cluster tightly, but with cooling, the polymer gels absorb water and then expand to push the nanoparticles apart.

"It's like an explosion," said Tao Ding from the University of Cambridge and first author of the study. "We have hundreds of gold balls flying apart in a millionth of a second when water molecules inflate the polymers around them."

"We know that light can heat up water to power steam engines," added Ventsislav Valev, a co-author of the study who is currently at the University of Bath. "But now we can use light to power a piston engine at the nanoscale."

The new technique can solve the problem of making nano-machines move and exert large forces.

The new engine creates forces that are huge. It creates a force per unit weight that is one hundred times that created by a motor or a muscle. Moreover, the engines are cost-effective, bio-compatible and energy efficient.

"Like real ants, they produce large forces for their weight," said Jeremy Baumberg from the Cavendish Laboratory, who led the study and has named the devices "ANTs." "The challenge we now face is how to control that force for nano-machinery applications."

The team hopes to put the technology to use in microfluidics bio-applications.

The findings were published in the May 2 issue of the Proceedings of the National Academy of Sciences.