Micromachined Graphite Rotor Based on Diamagnetic Levitation

This letter reports the first micromachined rotor of highly oriented pyrolytic graphite (HOPG), a strong diamagnetic material. The HOPG rotor is levitated above a permanent magnet structure to allow for its friction-free rotation. The 600- $\mu $ m-thick HOPG rotor is micropatterned to have four blades with 1-mm inner diameter disc and 2-mm outer diameter including the blades. The levitation height of 132 $\mu $ m measured for the rotor matches well with a simulation result. The revolution of the rotor is demonstrated by applying gas flow, showing stable continuous actuation with the maximum rate of 500 r/min. These promising results suggest potential applications of the mechanism toward frictionless microsensors and microactuators.