Actively Controlled Hexapole Electromagnetic Actuating System Enabling 3-D Force Manipulation in Aqueous Solutions

This paper presents the design, modeling, and calibration of an overactuated and actively controlled hexapole electromagnetic actuating system, which is implemented to stabilize and propel a microscopic magnetic particle in aqueous solutions. Compared to the 2-D quadruple magnetic tweezers in the paper by Zhang et al. ( IEEE/ASME Trans. Mechatronics, 2010) and the 3-D magnetic actuator in the paper by Zhang and Menq ( IEEE/ASME Trans. Mechatronics, 2011), the new electromagnetic actuating system achieves significantly greater force generation capability and much improved controllability of 3-D force in the workspace. These improvements are accomplished through enhanced design and synthesis of the six electromagnetic poles and improved current allocation of the overactuated system. A lumped parameter hexapole force model of the system is derived and validated through experimental calibration. It is then used to devise inverse modeling, which is implemented to realize real-time current allocation to enable the most effective manipulation of the 3-D magnetic force exerting on the particle at the center of the workspace. The system is designed for use with live cell experiments.