Using polymer-coated gold nanoparticles, researchers at University of Cambridge and University of Bath developed a nanoscale sized engine that can even enter living cells to fight disease. How does this function? Below is the explanation given in the release from the University of Bath: "The prototype device is made using tiny charged particles of gold, bound together with temperature-responsive polymers in the form of a gel. When the ‘nano-engine’ is heated 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." The results of this research are reported in the journal PNAS. Expanding polymer-coated gold nanoparticles, Yi Ju University of Cambridge. “We know that light can heat up water to power steam engines,” said study co-author Dr Ventsislav Valev, from the University of Bath’s Department of Physics. “But now we can use light to build a piston for engines at the nanoscale.” “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.” If you'd like to what is the amount of force these tiny machines can produce, Researchers claim these nano machines are far more efficient than any motor or muscle, with a force per unit weight nearly a hundred times better than any motor or muscle. They are designed for bio-compatibility and costs lesser to manufacture. Professor Jeremy Baumberg from the Cavendish Laboratory, who led the research, has named the devices as ‘ANTs’, or actuating nano-transducers. “Like real ants, they produce large forces for their weight. The challenge we now face is how to control that force for nano-machinery applications.” The research is about utilising Van de Waals energy which is the attraction between atoms and molecules, Kind of creating elastic energy of polymers and release it very quickly. “The whole process is like a nano-spring,” said Baumberg. “The smart part here is we make use of Van de Waals attraction of heavy metal particles to set the springs (polymers) and water molecules to release them, which is very reversible and reproducible.” Researchers working on is in the area of "microfluidics bio-applications" to commercially apply this research.