Magnetic Induction Micromachine—Part II: Fabrication and Testing

Abstract

This paper presents the realization of a magnetic induction machine. The development of this machine is part of an ongoing project to create high-power density electric microgenerators for use in portable-power applications. The results reported here focus on testing a first-generation nonlaminated electromagnetic actuator, a metrology device designed for exploring and characterizing the fabrication process and the operating behavior of the magnetic induction micromachine. Achieving high power density requires large electrical currents and magnetic fluxes, which necessitate thick, multilayered microstructures that are difficult to fabricate. The batch-fabrication schemes developed as part of this work are based on low-temperature micromolding that makes extensive use of various ultra-thick photoresists and electroplating of electrical conductors (Cu) and ferromagnetic materials (Ni-Fe 80%-20%), resulting in the successful fabrication of a multilayer two-phase planar stator and a planar rotor. To evaluate the performance of the complete machine (stator plus rotor), a 4-mm-diameter, 500-m-thick electroplated Ni-Fe rotor is tethered to a series of flexible structures that prevent it from making a complete revolution, but allow accurate torque performance extraction. The tethered induction micromotor studied here exhibits torque production as high as 4.8 N m.[1436]

Design and modeling of a six DOFs MEMS-based precision manipulator

“…Another example where four wafers are stacked is given in [27] for a 2 DOFs tilt mirror with buried actuators. An assembled magnetic induction machine is presented in [28] and [29]. Here, a rotor structure is assembled on top of a molded coil structure.…”

Development of an Axial Flux MEMS BLDC Micromotor with Increased Efficiency and Power Density

“…In reference [1], a micromotor was designed with special emphasis on the maximization of its efficiency. The Joule efficiency obtained is about 42%, which is much higher than those reported for electromagnetic MEMS micromotors [4,5]. However, the capability of its output torque is only 3.78 nNm due to its micro dimensions (external diameter is 2.6 mm).…”

A brief review of actuation at the micro-scale using electrostatics, electromagnetics and piezoelectric ultrasonics

“…The induced eddy currents in the rotor interacts with the travelling magnetic wave, resulting in a net torque and an attractive force between the stator and rotor. Two top-drive micromotors using Ni-Fe cores have recently been reported: one with a 10-mm-diameter-rotor and a stall torque of up to 2.5 mNm [22], and one with a 4-mm-diameter-rotor and a stall-torque of up to 4.8 mNm [23]. Both were fabricated and tested with a tethered rotor to avoid the complexity of designing the bearing.…”