Parallel Assembly of Hinged Microstructures Using Magnetic Actuation

We have developed a new surface-micromachining process for realizing three-dimensional MEMS devices from hinged planar stmchlres. Magnetic actuation, which is provided by Permalloy material attached to hinged plates, provides efficient and highyield out-of-plane actuation. Parallel actuation of large arrays of hinged microstructures is achieved under a globally applied external magnetic field. The magnitude of the actuation can be controlled by either the volume of the magnetic piece or the stiffness of a flexural-beam loading spring. Asynchronous displacement of hinged structures allow these devices to lock into three dimensional assemblies that remain stable after the activation magnetic field is removed. no influence on existing designs and recipes. If an external magnetic field is applied perpendicular to the substrate (Fig. Ic), the Pemuxlloy material develops a magnetization, M. It subsequently interacts with Hex, to induce a torque, T, on the hinged structure and causes it to deflect away from the substrate plane. ‘Ibe magnitude of T is given by: where A and lnog are the cross-sectional area and the length of the Permalloy piece, respectively, and 0 represents the angle between the flap and the substrate.