TL;DR
Every science-fiction nanobot, from the ones that swim through blood vessels to the ones that repair cells, needs an engine, and engines are hard to build when the whole machine is a few billionths of a meter across. A team led from the University of Augsburg has built one kind: a single spiral-shaped molecule, shaped like an Archimedes screw, that spins when electric current runs through it and spins the other way when the voltage flips. Better still, it gets up to 100 times better at carrying current while it turns. It is a lab prototype held between two gold tips, a building block rather than a robot, but it points at tiny machines powered by plain electricity instead of light or chemical fuel. To see our odds on when molecular motors like this end up inside working nanoscale devices, and the timeline of breakthroughs that leads to medical nanorobots, subscribe.
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