A tiny zinc object that can propel itself from one end of a capillary tube to the other holds promise for those striving to make minuscule motors.
Gabriel Loget and Alexander Kuhn at the University of Bordeaux in France immersed their micrometre-sized zinc 'swimmer' in a solution of zinc sulphate and applied a relatively weak external electric field. The field promotes oxidation on one side of the swimmer, dissolving the zinc, and reduction on the other, which deposits zinc, thus moving the object along. The swimmer reached speeds of 80 micrometres per second.
The authors suggest that their method could be an efficient way to control the motion of metallic micro-objects in engineered micromotors — or perhaps even nanomotors.