This robot is modeled on the peekytoe crab. It is small enough to walk on the edge of a coin. They are only half a millimeter wide.
These robots are very rudimentary, but I can see a great many applications. Imagine programming a swarm of these to remove cancer inside your body. Would be very efficient and not as invasive as surgery.
Of course, these kinds of robots are also the stuff of dystopian science fiction. Read “Prey” by Michael Crichton.
But the tech is way cool.