A new nanoscale transducer, created by researchers at the University of Cambridge, is the world’s tiniest engine at just a few billionths of a metre in size. The engine, which uses light to power itself, could be the basis of future nano-machines that can navigate in water, sense the environment around them, or even enter living cells to fight disease.
The prototype device is comprised of tiny charged particles of gold, held together with temperature-responsive polymers in the form of a gel.
When this nano-engine is heated up 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. This has the effect of 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.
Nano-machines have long been a goal of scientists, but since ways to actually make them move have yet to be developed, they have remained in the realm of science fiction. The new method developed by the Cambridge researchers is incredibly simple, but can be extremely fast and exert large forces.
Study co-author Dr Ventsislav Valev, now based at the University of Bath, said:
Dr Tao Ding from Cambridge’s Cavendish Laboratory, and the paper’s first author, added:
The forces created by these tiny devices are several orders of magnitude larger than those for any other previously produced device, with a force per unit weight nearly a hundred times better than any motor or muscle. According to the researchers, the devices are also bio-compatible, cost-effective to manufacture, fast to respond, and energy efficient.
Professor Jeremy Baumberg from the Cavendish Laboratory, who led the research, has named the devices ‘ANTs’, or actuating nano-transducers.
Image: Yi Ju/University of Cambridge NanoPhotonics