A study published in the Proceedings of the National Academy of Sciences states that scientists from the University of Cambridge have built the world’s tiniest engines that is powered by light. The engine is just a few billionths of a metre in size and can navigate in water, sense the environment around them or even enter living cells to fight disease.
The prototype device known as ANTs or actuating nano-transducers is made up of tiny charged particles of gold bound together with temperature-responsive polymers in the form of a gel. Whenever the gel is heated with the help of a laser, the polymer gel responds by expelling all its water in a fraction of a second and collapses much like a coiling spring.
The smashing of gold nanoparticles stores large amounts of elastic energy and upon cooling the water gets re-absorbed quickly wherein the stored energy pushes the gold nanoparticles with tremendous force. “It’s like an explosion,” said Dr Tao Ding from Cambridge’s Cavendish Laboratory, and the paper’s first author. “We have hundreds of gold balls flying apart in a millionth of a second when water molecules inflate the polymers around them.” Researchers now need to focus on getting the particles concentrated into something more akin to a piston in a steam engine. In real world applications, the ANTs could be used to power tiny nanobots for targeted drug delivery or robotic surgery.