Carbon dioxide bubble-propelled microengines in carbonated water and beverages.

We demonstrate a new type of gaseous fuel for rolled-up tubular Ti/Cr microengine powered by carbon dioxide microbubbles in carbonated water and brewed beverages. Existence of microbubble pockets is revealed using on-chip integrated transparent microtubes. Vertical position, angle of rotation and buoyancy of ferromagnetic Ti/Fe/Cr microengines are controlled using an external magnetic field.