Trapping and orientation control of parametrically excited magnetic particles

Trapped micro-particles are used as end-effectors in many micro-manipulation technologies. Recently, magnetic particles were shown to be trapped by means of parametric excitation. In this paper, a system is proposed to add angular degrees of freedom to the trapped magnetic end-effector about two independent axes. First, a dynamic model is developed for a trapped magnetic particle oriented at an arbitrary fixed direction. Next, the stability of trapped magnetic particles is studied and is shown that the particle stays trapped even for large changes in orientation. Dehmelt approximation has been employed to obtain the approximate secular dynamics of the particles and the simulation results are shown to be in good agreement with numerical calculations. Next, an experimental setup has been developed to trap and orient magnetic particles. The setup has been employed to demonstrate the ability to trap magnetic particles and change their orientation by large angles. Such reoriented particles have also been moved and shown to track square trajectories. Finally, the step-response of the trapped particle has been obtained and is shown to display second-order secular dynamics, which is in alignment with the proposed theoretical model.