The glass nano-devices can push objects 1000 times their own size (Image: 2009 American Chemical Society)

REMOTE-CONTROLLED nano-devices that look like sperm but mimic the corkscrew motion of flagella may one day deliver drugs to where they are needed in the body.

Flagella are the structures some bacteria use to swim through water. Because water is syrupy at small scales, ordinary swimming motions don’t work well. “Picture trying to swim in a pool of asphalt on a hot summer’s day,” says Peer Fischer of The Rowland Institute at Harvard University. Instead, flagella use a corkscrew motion to drive bacteria …