Magnetically actuated microrotors with individual pumping speed and direction control

We demonstrate an experimental realization of a microscale pump self-assembled from superparamagnetic colloidal spheres and driven by an external magnetic field, where a system of microelectrodes controls the pump rotor by dielectrophoretic force. Whereas an external magnetic field is used to assemble and drive the rotor, which allows parallel fabrication and actuation of many such devices, the microelectrodes enable control of an individual rotor and thus regulate pumping speed and direction of any single pump in the microfluidic device. Dielectrophoretically controlled micropumps can be fabricated with existing microfabrication techniques and can be easily integrated into complex microfluidic devices.