A Heartbeat-Powered Pacemaker Worked in a Pig for One Month

A pacemaker that draws electricity from the heart's own movement has crossed an important preclinical test. University of Wisconsin-Madison engineers placed their generator inside a leadless pacemaker-sized capsule and showed that it could deliver cardiac stimulation during a month-long implant study in one pig.

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The prototype remained implanted for one month, far short of the years of reliable operation a clinical pacemaker must prove.

Why removing the battery could matter

Leadless pacemakers sit inside the heart rather than connecting to it through wires from a chest implant. Their compact design avoids a surgical pocket and transvenous leads, but the battery still lasts roughly seven to ten years and accounts for more than half of the device's size and weight, according to the University of Wisconsin-Madison project report.

Removing a depleted capsule can be difficult, so clinicians may leave it in place and implant another device. A generator that reliably runs for decades could reduce repeated procedures, especially for younger patients. That potential resembles the long-term promise of other implants, including the approved PRIMA retinal implant, but this pacemaker has not reached human testing.

How the tiny generator makes electricity

The team replaced the battery compartment with pairs of small plates coated with copper and fluorinated ethylene propylene. Heart motion presses the oppositely charged surfaces together and separates them again, producing electricity through the triboelectric effect. A capacitor can store part of that charge for pacing pulses.

Bench tests reported a power density of 276.6 microwatts per cubic centimetre. The peer-reviewed Science Advances paper describes the design as a self-sustaining leadless intracardiac pacemaker. The researchers sized the generator to fit the space occupied by a battery in a Micra-style capsule, whose clinical format is described in Medtronic's patient information.

What the pig experiment actually showed

The team implanted one prototype and monitored performance and tissue compatibility for a month. During functional testing, the generator supplied cardiac stimulation, while the study reported no adverse response beyond what would be expected from a conventional leadless pacemaker.

This is not the first attempt to harvest heartbeat energy. An earlier pig study published in 2024 also demonstrated a self-powered intracardiac system. The new result matters because the oscillating structure was designed for higher power density within an established leadless-pacemaker envelope, not because it proves lifelong operation.

What must happen next

The engineers need to convert irregular cardiac motion into stable oscillation, then show consistent power across animals, heart rates and body positions. Long-duration fatigue testing must also demonstrate that millions of contact cycles do not weaken the plates or surrounding materials.

The useful milestone is narrower than the headline promise of a lifetime pacemaker: the team fitted an energy harvester inside a realistic leadless form and made it pace a pig's heart. The unresolved test is whether that power remains sufficient, stable and safe for years rather than one month.