Linear variable reluctance (VR) micro motors with compensated attraction force:: Concept, simulation, fabrication and test

This paper reports on optimized fabrication technologies for electromagnetic actuator systems and their characterization. These actuators consist of three-dimensional microstructures of increasing complexity like electroplated micro coils, flux guidances, insulation and planarization layers. The microstructures are fabricated by UV depth lithography using AZ9260, electrodepositable photo resist and Epon SU-8. Electroplated nickel iron and copper is used for the generation of flux guidance and coils. The magnetic flux is generated and guided in plane by a three dimensional double meander coil wound around laterally toothed stator poles. The traveller's comb shaped poles reach in between the stator poles and, therefore, are attracted from both sides. Thus, the attraction forces exceeding thrust, common to any VR-motor concept, are eliminated. The micro actuator was simulated, fabricated and successfully tested.