Scientists build World’s Tiniest Machine | Can Bring Revolution in Medicine

Scientists at the University of Cambridge have built the world’s tiniest engine which is powered by light. Dubbed “ANTs” (for actuating nano transducers), these itsy-bitsy devices are actually a million times smaller than a black and small ant.

The nanoscale engine works like this: at the heart of the device are lots of charged gold nanoparticles, held together by a polymer gel that responds to changes in temperature. The gel is heated by zapping it with a laser. The polymer gel responds by expelling all its water in a fraction of a second and collapsing, much like coiling a spring. This stores elastic energy as the gold nanoparticles cling together and form tight clusters thanks to the van der Waal’s force.

As the device cools, the gel will re-absorb water to expand just as quickly, releasing that stored energy to push the gold nanoparticles apart with tremendous force.
The ANTs convert energy from the molecular attraction between heavy metal particles into elastic energy to create a kind of nano-spring—a true transducer. But to make a bona fide actuator, the researchers need to figure out how to focus the forces—which currently push in every direction—into something more akin to a piston in steam engine.

As for real-world applications, the ANTs could indeed power tiny nanobots someday for things like targeted drug delivery or robotic surgery. In the short term, the Cambridge team is tackling the far simpler goal of making tiny light-controlled pumps and valves for better microfluidic chips—the sort used in diagnostic kits and biosensors. “No electric wires would be needed, so we could put many on a small chip,” said Baumberg.

The research was published in the Proceedings of the National Academy of Sciences.

Prapti Shah Gandhi
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