It sounds like the theoretical impossibility of perpetual motion, but engineers at the University of Michigan have created a pacemaker that is powered by the beating of your heart — no batteries required.

The technology behind this new infinite-duration pacemaker is one that we’ve discussed before at length on ExtremeTech: piezoelectricity. Piezoelectricity is literally “pressure electricity,” and it relates to certain materials that generate tiny amounts of electricity when deformed by an external force. Piezoelectricity is exciting because it can harvest energy from kinetic energy that is currently wasted — the vibration of machines, the straining of floorboards in public/commercial spaces, the wobbling of bridges, the soles of your feet as you walk.

the perpetual pacemaker , the vibrations in your chest as your heart pumps blood around your body. Piezoelectric devices generate very small amounts of power — on the order of tens of milliwatts — but it turns out that pacemakers require very power, too. In testing, the researchers’ energy harvester generated 10 times the required the power to keep a pacemaker firing.

Currently, pacemakers are battery powered — and the battery generally need to be replaced every few years, which requires surgery. According M. Amin Karami, the lead researcher, “Many of the patients are children who live with pacemakers for many years,” he said. “You can imagine how many operations they are spared if this new technology is implemented.” This piezoelectric energy harvester is about half the size of a conventional battery, too, which is presumably a good thing.

Moving forward, Karami and his team now plan to integrate its energy harvester with commercial pacemakers, so that it can actually be used by patients. The team has already tested the harvester’s ability to create enough electricity from as few as 20 beats per minute, or as many as 600 — but there’s probably a lot of reliability testing that needs to be done before the FDA or EU approve it. Karami also says that other biomedical devices, such as defibrillators, could also be powered by similar piezoelectric harvesters.

But why stop there? It’s quite alluring to imagine a whole network of computers and sensors and actuators underneath our skin, powered by our body heat and movements. Imagine if everyone, from birth, was given a built-in defibrillator. Would deaths from cardiac arrest plummet? What if we had some kind of battery pack that could save up energy, and then deliver an extra burst of power when fleeing from knife-wielding maniacs? For more on that topic, though, read this story: Will your body be the battery of the future?