You'll be injecting robots into your bloodstream to fight disease soon

What if there was a magical robot that could cure any disease? Everyone knows there's no one machine that could do that. But maybe a swarm made up of tens of thousands of tiny autonomous micro-bots could? That's the premise laid out by proponents of nanobot medical technology. In science fiction, the big idea usually involves creating tiny metal robots via some sort of magic-adjacent miniaturization technology.