Micro Ultrasonic Motor Using a Cube with a Side Length of 0.5 mm

Actuator miniaturization to submillimeter scales encounters difficult fabrication and serious torque dissipation caused by adhesion forces. This study presents a design for micro ultrasonic motors that enables microfabrication and motor actuation. The stator prototype, which is the smallest ultrasonic motor reported to date, comprises a metallic cube with a side length of 0.5 mm and a through-hole of 0.33-mm diameter at its center, and two piezoelectric elements adhered to its sides. Under two different applied voltages, the stator generates a driving force and transfers it to the rotor inserted in the through-hole. Performance assessments show that this micromotor generates an average angular velocity of 123 rad/s and a peak torque of 0.2 μN·m. This torque value exceeds that of the existing micromotors.