Scientists have long envisioned building tiny robots capable of navigating environments that are inaccessible or too dangerous for humans -- but finding ways to keep them powered and moving has been impossible to achieve. A team at the University of Southern California has now made a breakthrough, building an 88-milligram (one three hundredth of an ounce) "RoBeetle" that runs on methanol and uses an artificial muscle system to crawl, climb and carry loads on its back for up to two hours.