It’s no Michael Phelps, but this tiny magnetic robot
The front crawl is the fastest way for humans to swim. So Tianlong Li at the Harbin Institute of Technology in China and his colleagues built their swimming robot to mimic that motion.
Each nano-swimmer is 5 micrometres long and has three main parts, connected together like sausage links by two silver hinges. Its gold body is flanked by two magnetic arms made of nickel, and applying a magnetic field to the tiny robot makes the arms move.