In this class we designed and tested mirco robots made from MEMS fabrication, which is similar to computerchip fabrication. The robot contains polymer and metal.
The motion of the robot is generated from the capacitive surface that the robot is on. Changes in electric field will allow the robot to deflect to produce motion.
The design you see in this video contains two hanging masses on feet. The masses resonate at different frequencies allowing the robot to turn when specific electric frequencies are applied.