Stick-slip Motion Style of Magnetic Field Actuated Microrobots

In this paper, we report a novel motion style of microrobots actuated by magnetic field. The instability introduced by the alternative magnetic field leads to the stick-slip pattern of microrobot movement. And, by combining two iron balls at microscale together, the dimer microrobots are fabricated and studied in the motion experiment. The dependencies of stick-slip motion speed on the frequency, waveform of actuation signal and the size of both monomer and dimer microrobots are systematically investigated to clarify the underlying mechanism of this motion style. Motion speed tends to increase as signal frequency increases first, and then decrease when the frequency goes high. Smaller size of microrobots can move faster. And waveform is demonstrated to have significant impact on the motion speed. Finally, we reveal that alternative magnetic field drive both monomer and dimer microrobots with size of hundreds of microns to move in a stick-slip style; and the motion speed can be tuned through the actuation signal frequency. Furthermore, through modulating the generated magnetic field, the motion direction is promised to be controlled as well.