Reduction of the Nested Solenoid Micro-Coil Size as a Path to Transporter Micro-Actuator Array

In this paper, we report on the novel technological approach for the miniaturization of 3D inductive levitation microactuators (3D-ILMA) realized via the nested solenoid micro-coils. The developed technological approach allows the solenoid micro-coil fabrication separately from each other, beginning with the smallest innermost coil of the nested microstructure. The established process flow helps to overcome fabrication restrictions due to the wirebonding process primarily caused by the size of the bond-head limited to 600 micrometer, and provides the opportunity to fabricate nested 3D micro-coil structures of a smaller size. Here, we fabricated a nested two micro-coil structure, the inner coils having a diameter of 1000 micrometer and 14 windings, the outer coil with a diameter of 1900 micrometer and 8 windings, and demonstrate its application as the inductive levitating micro-suspension. In particular, a fabricated 3D inductive levitating micro-suspension was able to levitate a 1100 micrometer diameter disc-shaped proof mass to a height up to 45 micrometer. Such miniaturization is further utilized for arrays of micro-coils.