Scientists at the University of Wisconsin–Madison have developed an experimental pacemaker that can collect energy from the beating heart instead of depending on a conventional battery.
If the technology eventually works safely in people, it could help solve one of the biggest limits of today’s tiny pacemakers: batteries that eventually run out.
Pacemakers are small medical devices that send electrical signals to the heart when its natural rhythm becomes too slow or irregular. Modern pacemakers can watch the heartbeat and deliver electrical stimulation only when it is needed. For millions of patients, these devices can improve daily life and sometimes provide lifesaving support.
Traditional pacemakers are usually placed under the skin in the chest and connected to the heart with thin wires. Newer leadless pacemakers are much smaller and can be placed directly inside the heart through a blood vessel. This avoids the chest pocket and connecting wires that can sometimes cause complications.
But making a pacemaker smaller does not eliminate the battery problem. In some leadless devices, the battery accounts for more than half of the device’s size and weight and may last roughly seven to 10 years. Replacing a device inside the heart can be difficult, and an old unit may sometimes be left in place when another one is implanted.
That can become a particular concern for younger patients who may need pacing for decades. A person could potentially require several replacement devices during a lifetime. Each additional procedure can bring costs and medical risks.
The Wisconsin team asked whether the heart itself could supply the needed energy. Led by postdoctoral researcher Pengfei Chen and professor Xudong Wang, the engineers designed a very small generator that turns movement from each heartbeat into electricity. Their research was published Aug. 19, 2026, in Science Advances.
The generator was designed to fit into the space normally occupied by the battery in a Medtronic Micra leadless pacemaker without making the overall implant larger. Inside are tiny structures that move as the heart beats. Two surfaces with different electrical properties repeatedly touch and separate as the device moves.
That movement creates a small electrical charge. The electricity can then be used to operate the pacemaker or stored temporarily in a small component inside the device. The basic idea is similar to collecting tiny amounts of energy that would otherwise be lost as mechanical motion.
Producing enough electricity in such a tiny space was a major challenge. Wang said the important measure is not simply total energy but how much power can be produced within a very small volume. The researchers reported a laboratory power output of 276.6 microwatts per cubic centimeter.
According to the team, this was enough to operate the pacemaker and was much higher than the output of earlier miniature devices designed to collect energy from movement. The engineers also had to make the moving parts flexible enough to respond to each heartbeat but strong enough to survive millions of repeated movements.
The researchers then moved beyond laboratory testing and implanted a prototype in a pig. They monitored it for one month and tested whether the generator could support electrical stimulation of the heart.
The device successfully powered cardiac stimulation during functional testing, and the researchers reported no unexpected harmful reactions beyond those associated with conventional leadless pacemakers.
The animal experiment is an encouraging step, but the device is not ready for patients. The generator produced less power inside the pig than it had during laboratory tests. Soft heart tissue absorbed some of the movement that the generator needed to produce electricity.
The heart also does not simply move straight up and down. It bends, squeezes and twists as it pumps blood, while the experimental generator works best with a more regular back-and-forth movement. The researchers are now trying to redesign the system so it can capture more energy from the heart’s complicated natural motion.
Cardiac electrophysiologist Dr. Daniel Modaff, a study co-author, said avoiding battery replacement could be an important advance for patients. The long-term goal is an implant that could potentially remain useful for a person’s lifetime rather than requiring another procedure when its battery is exhausted.
The study is impressive because the researchers did not merely demonstrate energy production on a laboratory bench. They built the generator around the strict size limits of an existing leadless pacemaker and tested a prototype in a large animal. That makes the work more relevant to possible future medical use.
Still, the lifetime-pacemaker idea remains a goal rather than a proven result. A one-month pig study cannot show whether the generator will keep working reliably for 10, 20 or 30 years, and the lower energy output inside the body is an important problem that must be solved. Human trials will also be needed to examine safety, reliability and long-term performance.
If those challenges can be overcome, the technology could have uses beyond pacemakers. A dependable source of electricity harvested from the body might allow engineers to build smaller implants with more sensors and other functions. For now, the research provides an intriguing demonstration that the heart may one day help power the very device that keeps it beating properly.
Source: University of Wisconsin–Madison.
