
The device is etched out of silicon and measures 20-microns (about one fifth of a human hair). It's shaped like flower with six petals and feet stick out from underneath. The feet drop into a groove which houses the bacteria. A special protein causes the bacteria to all move in one direction, pushing against the feet and thereby spinning the motor at a speed of about two rotations per minute.
The device is believed to be the first example of a 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.