The use of swarms of nanobots to perform seemingly miraculous tasks is a common trope in the annals of science fiction.1 Although several of these remarkable feats are still very much in the realm of fiction, scientists have recently overcome many of the physical challenges associated with operating on the small scale and have generated the first generation of autonomous self-powered nanomotors and pumps. The motors can be directed by chemical and light gradients, pick up and deliver cargo, and exhibit collective behavior.