Researchers from Northwestern University, Princeton, and Argonne National Laboratory used bacteria swimming in liquid to turn tiny gears suspended in the same medium. Various gear designs have already been developed (side image) that can harness the power of the bacteria. We recently reported on a project out of the University of Rome that has achieved what seems like the same feat. If it proves to be practical, this technology may one day power implantable medical microdevices.
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.
The speed at which the gears turn can also be controlled through the manipulation of oxygen in the suspended liquid. The bacteria need oxygen in order to swim, and by decreasing the amount of oxygen available, researchers can slow down the gears’ movement. Eliminating the oxygen halts the movement entirely.
Once the oxygen is reintroduced into the system, the bacteria “wake up” and begin swimming once again.
Press release: Argonne scientists use bacteria to power simple machines
Flashback: Scientists Enslave Bacteria to Power Tiny Microsized Motor