We can't even design water pipes and valves that don't degrade over time. Limescale builds up and clogs the works. There's only a tiny amount of minerals in wat

We can't even design water pipes and valves that don't degrade over time. Limescale builds up and clogs the works. There's only a tiny amount of minerals in water, and yet that happens. Blood -- as they say -- is much thicker than water, and contains components specifically designed to clot. It's not wonder that this is a tricky problem to solve.