Scientists can simulate organs on chips when testing medicine, but mimicking your natural rhythm is another matter -- it's hard to know if those drugs will behave properly under the stresses of your body. That won't be a problem when the University of Michigan's newly developed testing chip comes into play. The device uses microscopic, gravity-powered fluid channels to replicate heartbeats and other natural flows (such as brain signals) when testing chemicals. You'll know if that treatment works properly when the patient's heart is racing, for example. And unlike previous attempts at emulating heartbeats, you don't need to stick around pumping fluid yourself -- you can conduct long-term tests that reflect what would happen in a real body over time.