A Four-magnet System for 2D Wireless Open-Loop Control of Microrobots

This paper presents a novel permanent magnets based actuator capable of injecting and 2D wireless control the motion of an untethered microrobot. The actuator is obtained with a simple, but an effective arrangement of four permanent magnets. Its novelty is that it creates local maxima of the magnetic field magnitude in a planar workspace. This results in a convergence point for magnetic microrobots that are in its influence zone. Trapping microrobots in the local maxima makes their open-loop guidance possible, even in presence of reasonable perturbations. Actually, open-loop control is the only way to achieve some drug delivery when there are no sensors to provide us a feedback on the microrobot's positions. With the proposed actuator, the workspace is reduced, the movement is simplified and the actuator orientation is not needed anymore. Experimental results are provided in the paper to show the soundness of the proposed actuator design.