Tiny “submarines” that speed independently through the stomach, use gastric acid for fuel (while rapidly neutralizing it), and release their cargo precisely at the desired pH: Though it may sound like science fiction, this is a new method for treating stomach diseases with acid-sensitive drugs introduced by scientists in the journal Angewandte Chemie. The technique is based on proton-driven micromotors with a pH-dependent polymer coating that can be loaded with drugs.