Several scientists and researchers around the world are manufacturing "microbots" -- an assortment of free-roaming robots that carry out precise, delicate tasks inside the human body. For example, a minibot named Steerable Surgeons is made of flat nickel parts assembled to make a 3-D tool that can be used during retinal surgeries, in drug therapy and for ocular disease. Its power sources are external electromagnetic coils, and it uses magnetic field gradients as a steering mechanism.
Similar to Steerable Surgeons are microbots such as Robot Pills and Plaque Busters. Robot Pills are designed as a capsule that contains a magnet, camera, wireless chip and a set of mechanical legs. It's powered by DC motors and magnets outside of the body, and it uses a camera and wireless telemetry system. The Robot Pill is about two centimeters long and clinicians use it in disease screening.
Similarly, Plaque Busters are magnetic capsules equipped with a micro drill head. Surgeons use these microbots, which are 10-mm long, to remove plaque from arteries. They're powered by electromagnetic coils and use magnetic field gradients to steer.