A first functional current excited planar rotational magnetic micromotor

Complete integration and successful testing of a planar rotational magnetic micromotor have been demonstrated. The configuration is that of a three-phase variable reluctance stepping motor with 6 stator poles and 4 rotor poles. Stator and rotor heights of up to 300 mu m are available and rotor diameters of 285 mu m and 423 mu m were tested. Maximum rotational speeds which have been achieved with open loop excitation exceed 30000 rpm and show no change with operation in vacuum. After testing to more than 5*10/sup 7/ rotation cycles, deviations from initial operation are not observed. Vertical reluctance forces are used to levitate the rotor up to 50 mu m over the substrate. Position signals are available via integrated photodiodes which allow the rotor speed to be monitored and provide the groundwork for an active closed-loop system.<>