Researchers at the U.S. Department of Energy’s (DOE) Argonne National Laboratory and Northwestern University have discovered a way to let common bacteria turn microgears when suspended in a solution. The microgears are just 380 microns long but are a million times more massive than the bacteria. Several hundred bacteria work together in order to turn the gear, and the rotation speed can be controlled by adjusting the oxygen levels.
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“The ability to harness and control the power of bacterial motion is an important requirement for further development of hybrid biomechanical systems driven by microorganisms," said Argonne physicist and principal investigator Igor Aronson. “In this system, the gears are a million times more massive than the bacteria."
The microgears, just 380 microns long with slanted spokes, are produced in collaboration with Northwestern University and placed in the solution along with the common aerobic bacteria Bacillus subtilis. Andrey Sokolov of Princeton University and Igor Aronson from Argonne, along with Bartosz A. Grzybowski and Mario M. Apodaca from Northwestern University, observed that the bacteria appeared to swim at random—but occasionally the organisms collided with the spokes of the gear and began turning it in a definite direction.
A few hundred bacteria work together in order to turn the gear. When multiple gears are placed in the solution with the spokes connected as in a clock, the bacteria will turn both gears in opposite directions, causing the gears to rotate in synchrony—even for long stretches of time.
“There exists a wide gap between man-made hard materials and living tissues; biological materials, unlike steel or plastics, are 'alive,'" Aronson said. "Our discovery demonstrates how microscopic swimming agents, such as bacteria or man-made nanorobots, in combination with hard materials, can constitute a ‘smart material’ which can dynamically alter its microstructures, repair damage, or power microdevices."