High up on the list of things that it seems like a very bad idea to swallow are hydrogen-powered rockets. But researchers looking for new ways to deliver drugs inside the stomach have developed little microrockets powered by microbubbles and steered by micromagnets that are apparently perfectly safe to ingest. Yum?
At just ten micrometers long, these rockets are each about the size of one of your red blood cells. They consist of polymer tubes packed with zinc, and when the zinc comes in contact with an acid (like all that stuff bubbling away in your stomach), it reacts to release hydrogen. Jets of tiny hydrogen bubbles shoot out the back of the tube pushing it forward, and bam, you've got yourself a rocket. Its top speed is 100 body-lengths per second, which is hugely fast, and there's a video below with some footage of these things speeding around.
To control the microrockets, a layer of magnetic material is deposited on the outside of the tube, and external magnets are used to start, stop, and steer. The level of control is fine enough to enable the microrockets to pick up and drop off little cargo modules which may eventually contain drugs.
As far as getting the microrockets out of your body, it's not really a problem. All the zinc dissolves within just a few minutes, and then you've just got that tiny little polymer tube left, and that's not going to hurt you. Oh, and there's no word on how these things taste, but we imagine that the flavor is probably something akin to Arugula.