It's difficult to spot cancer cells -- just one in a billion blood cells are cancerous. How do you isolate them to know the trouble someone is facing and eventually treat it? By drawing the kind of mazes you enjoyed as a kid, apparently. Researchers have developed a microfluidic chip that uses a circular labyrinth to separate cancer cells from the rest of your bloodstream and spot the stem-like cells that will aggressively spread that cancer. Ultimately, it's a creative use of physics. The curves tend to push larger cancer cells forward (smaller regular cells cling to the walls), while the corners mix things up and put white blood cells in an ideal position.