A universal electromagnetic microactuator using magnetic interconnection concepts

This paper describes a new universal electromagnetic microactuator that makes use of novel magnetic interconnection concepts. In order to realize the universal actuator, planar microinductors are fabricated on a substrate which already contains anisotropically etched Ni/Fe permalloy-electroplated magnetic vias or through-holes. The inductor, which acts as a flux generator, is physically located on one side of the wafer, but is magnetically connected to the opposite side of the wafer where actuation occurs. This approach to actuator design provides for maximum flexibility in the range of applications. In addition, it allows the actuator to be readily connected to driving circuitry without interfering with the actuating device. Multi-layer 3D inductive components are fabricated using a LIGA-like thick photoresist lithography process. The fabricated coils consist of a horseshoe-shaped permalloy-electroplated magnetic core and electroplated copper conductor lines that form the windings around the core. Initial testing using a prototype cantilever beam structure has proven functionality and indicates that the new device has much potential as a low power magnetic microactuator. Many magnetic MEMS applications require an electromagnetic actuator with high efficiency, and some areas which this device is expected to impact include microfluidics, micromotors, optics, and resonating devices.