Homopolar Micromotor with Liquid Metal Rotor

In this paper, we present fabrication, test, and simulation results of a homopolar micromotor with liquid metal rotor. The micromotor´s stator is fabricated in a highly doped silicon wafer in which a droplet of liquid metal (rotor) is placed. The stator-rotor assembly is attached on top of the neodymium magnet. A DC current in the x-y plane in the presence of the magnetic field in the z direction generates an electromagnetic force which rotates the liquid metal. Using liquid rotor simplifies electrical connection to the rotating part and reduces friction and power loss in the micromotor. A 4times4times5 mm³ prototype of such a homopolar micromotor was fabricated. A rotation speed of 100 rpm was measured at 0.5 V (14 mA current consumption).