3D micro-machined inductive contactless suspension: Testing and modeling

We present herewith detailed theoretical modeling coupled with experimental analysis of a micromachined inductive suspension (MIS). The reported MIS is based on two coaxial 3D solenoidal microcoils realized using our wirebonding technology. The two coils are excited using an AC signal with 180° phase-shift and a conductive proof mass (PM) is stably levitated on top of the coils. Using a micromechanical displacement sensor, we experimentally derive the lateral, vertical and angular stiffness constants of our MIS. Based on the analytical model presented here, we discuss the stability of the levitated proof mass as a function of the geometrical parameters of the design. We further test our model by applying it to another previously reported MIS structure realized using planar technology, providing stability diagrams as well as design guidelines for further developments of the micromachined inductive suspension as, for instance, miniature rotating gyroscopes.