Modeling and Experimental Characterization of an Untethered Magnetic Micro-Robot

Here we present the control, performance and modeling of an untethered electromagnetically actuated magnetic micro-robot. The microrobot, which is composed of neodymium-iron-boron with dimensions 250 mu m x 130 mu m x 10 mu m, is actuated by a system of six macro-scale electromagnets. Periodically varying magnetic fields are used to impose magnetic torques, which induce stick-slip motion in the micro-robot. These magnetic forces and torques are incorporated into a comprehensive dynamic model, which captures the behavior of the micro-robot. By pivoting the micro-robot about an edge, non-planar obstacles with characteristic sizes comparable to the robot length can be surmounted. Actuation is demonstrated on several substrates with different surface properties, in a fluid environment, and in a vacuum. Observed micro-robot translation speeds can exceed 10 mm s(-1).