Moving coil type electromagnetic microactuator using metal/silicon driving springs and parylene connecting beams for pure in-plane large motion in three axes

In this paper, we report a three-degree-of-freedom electromagnetic microactuator with pure in-plane bi-directional displacement in X and Y and rotation about Z. Moving coil scheme was adopted because pure in-plane actuation without vertical displacement was possible under a uniform magnetic field. The actuator mainly consists of four driving units and a center moving stage within a footprint of 6 mm × 6 mm. Each of the driving unit is formed by four driving springs made of silicon and gold and connected by a moving shuttle. Parylene was employed to make spring beams to connect the center moving stage and the shuttles of four driving units. In-plane Lorentz force was generated by the coupling between current in the driving springs and a uniform outer magnetic field. By controlling the strength of current and outer magnetic field, an in-plane bi-directional displacement as large as ± 40 µm in X and Y and rotation angle of ± 2 degrees about Z were measured, the corresponding resonant frequencies were 650 Hz and 780 Hz, respectively.