For a machine the size of a virus, the rules of locomotion are weird and surprising. Water behaves like jittery molasses. Solids are sticky. Just hovering near certain surfaces can repel a tiny vehicle like a same-pole magnet would.
The nanoworld is also vast compared to the macroscopic one, and suitable materials to build motors for nanobots are limited at best.
“Trying to move a nano device at the speed and direction you want is like fighting a hurricane,” said nanotechnologist Daniela Wilson of Radboud University in the Netherlands. “It’s a real challenge to have complete control over the movement.”