Micromachined Active Magnetic Bearings

A disc-shaped rotor of 8 mm diameter and 1mm thickness has been levitated and rotated up to 3000 rpm in a miniature magnetic-bearing-motor combination. The levitation type is actively controlled using an optical sensing system in two radial directions. A second rotor of 5 µm thickness and 3 mm diameter is now being built along with four miniature stator magnets using micromachining technology of read-write magnets of disc storage devices. The machining consists of lithographic and electroplating processes. The bearing will be combined with an induction motor. Possible applications could include rate gyros.