Illustration. The real Johns Hopkins robots are about as wide as a pencil tip and as long as a grain of rice. The question is who they'll be built for. This is an opinion piece. The facts are sourced at the bottom. The conclusions are mine. Picture something about the size of a grain of rice. It has no battery. It has no motor. A magnetic field steers it from outside the body, and it carries medicine to exactly the spot where it's needed: an infection sitting on a human heart