A team of researchers from the University of Pennsylvania and the University of Michigan has developed a new robot that is smaller than a grain of salt, measuring only 200 x 300 x 50 micrometers. This experimental robot is smaller than a grain of salt. Fish and other large aquatic organisms move forward due to the reaction of water pushing backward, in accordance with the third law of motion in Newtonian mechanics. But pushing water on a microscopic scale is like pushing sludgy tar. The robot exploits the phenomenon that moving charged particles drag nearby water molecules, creating a water current around the robot.