Researchers led by Bradley Nelson of the Swiss Federal Institute of Technology (Zurich) have developed a method of propelling micro-robots inspired by the flagella of bacteria. Magnetic fields caused coils 27 nanometers think and 40 micrometers long to rotate at up to 60 revolutions per minute, which could propel an object at up to 5 micrometers per second. In comparison, bacteria use molecular motors that can rotate the helical filaments of their flagella at up to 1,000 revolutions per minute.
The technique allows micro-robots to overcome the increasing viscosity of liquids at microscopic scales. It could lead to delivery devices that can be steered to a precise site and more effectively deliver drugs.