Researchers from Argonne National Lab and elsewhere are finding ways to use the motion of swimming bacteria to move very tiny gears. The gear's shape directs a group of unsuspecting bacteria in such a way as to cause rotary motion. This motion can then be used to power tiny mechanical systems - possibly medical devices or maybe even tiny robots. Speed of the gears can be controlled by modulating the oxygen level within the suspension fluid - since bacteria love o2, feeding them more increases the speed while cutting off the supply stops motion.