Can robots travel inside living animals? It sounds like science fiction, but scientists have just made it a reality by implanting tiny nano-robots inside living mice. Researchers from the Department of Nanoengineering at the University of California, San Diego, published their report on the first successful tests of implanting micro robots designed to disperse drugs within a body, reports SmithsonianMag.com.

As the research report states, these kinds of robots have been tested “in vitro,” or outside the body, in the past, while this is the first time that this technology has been studied “in vivo,” or inside the body. The zinc-based robots — only the width of a strand of human hair — were ingested orally by the mice. The zinc reacted with the animal’s stomach acid, producing hydrogen bubbles that propelled the robots into the stomach lining. As soon as the robots attached to the stomach, they dissolved, delivering the medicine into the stomach tissue, i09 reports.

For the researchers, this work could pave the way for implanting similar robots in humans. This could be an effective way of delivering drugs to the stomach in order to treat something like a peptic ulcer, the BBC reports.

“While additional ‘in vivo’ characterizations are warranted to further evaluate the performance and functionalities of various man-made micromotors in living organisms, this study represents the very first steps toward such a goal,” reads the research report. According to the researchers, this work moves toward “expanding the horizon of man-made nanomachines in medicine.”