Engineers at the University of Colorado Boulder have designed tiny, self-propelled robots, each measuring only 20 micrometres in width, that can transport medication throughout the liquid-filled areas of the human body. Ride of that size is capable of travelling at speeds of up to 3 millimeters per second, and tests on lab mice suggest that microrobots could be used to treat bladder disease and other illnesses in humans. The specially designed robots, which look similar to small rockets, are made of materials called biocompatible polymers and each contain a small air bubble that vibrates when exposed to an ultrasound, propelling the robot’s forward motion.
https://www.colorado.edu/today/2023/05/24/these-tiny-medical-robots-could-one-day-travel-through-your-body