Scientists unveil world's tiniest engine

CAMBRIDGE, England, May 2 (UPI) -- Researchers at the University of Cambridge have built a nano-engine small enough to fit inside a living cell. The engine, which measures a few billionths of a meter in size, is composed of gold particles bound together by a temperature-sensitive, gel-like polymer.

The polymer reacts to heat, expelling water when warmed by a laser and taking on water as it cools. This expansion and contraction, pushes the gold particles apart and pulls them back together, creating a spring or piston-like action capable of generating a force many times its energy potential.

"It's like an explosion," Cambridge researcher Tao Ding said in a news release. "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," said researcher Ventsislav Valev, who now works at the University of Bath. "But now we can use light to power a piston engine at the nanoscale."

The force per unit of weight generated by the new motor bests those acheived by previous attempts to construct a nano-engine, and are 100 times greater than the forces generated by larger motors and animal muscles.

The tiny engines are also bio-compatible and energy efficient. Researchers say they can build them cost-effectively and at scale.

Past attempts at creating a reliable nanoscale motor have run into problems with control and predictability. It doesn't matter how a great a force an engine can create if the force can't be easily manipulated.

Researchers say the molecular and atomic forces of attraction the polymer takes advantage of are predictable and controllable.

The team of Cambridge scientists, who detailed their accomplishments in the journal PNAS, are now working with several companies to commercialize the technology for variety of biological applications.