A Technological Approach for Miniaturization of Three-Dimensional Inductive Levitation Microsuspensions

In this letter, we report on a technological approach for miniaturization of a inductive levitating microsuspension based on nested three-dimensional (3-D) microcoil structures. In the developed approach, each 3-D microcoil is fabricated separately, beginning with the innermost and thus the smallest coil diameter of the nested microstructure. This helps to overcome fabrication restrictions due to the wire-bonding process and is primarily caused by the size of the bond-head and provides the opportunity to fabricate smaller nested 3-D microcoil structures. We fabricated a nested two-microcoil structure, the inner coil having a diameter of 1000 $\mu$ m and 14 windings, the outer coil with a diameter of 1900 $\mu$ m and eight windings, and demonstrated its application as an inductive levitating microsuspension. In particular, a fabricated 3-D inductive levitating microsuspension was able to levitate a 1100 $\mu$ m diameter disc-shaped proof mass at a height up to 45 $\mu$ m.