Researchers at Japan's National Institute of Advanced Industrial Science and Technology have crafted a micro-motor powered by the movement of bacteria. 

The device is etched out of silicon and measures 20-microns (about one fifth the width of a human hair).

The micro-motor is shaped like flower with six petals and has 'feet' underneath which drop into a groove which houses the bacteria.

A special protein causes the bacteria to move in one direction, pushing against the feet and thereby spinning the motor at a speed of about two revolutions per minute.

The motor is believed to be the first micromechanical device to combine inorganic materials with living bacteria.

The researchers used a genetically modified version of one of the fastest known micro-organisms, the Mycoplasma mobile. It achieves speeds of up to seven tenths of an inch per hour.

Details of the device were published in the Proceedings of the National Academy of Sciences this week.