Every heartbeat creates movement, and researchers in Wisconsin want to put that movement to work.
A new experimental device can turn the motion of a beating heart into electricity for a pacemaker. The approach could eventually reduce the need for batteries inside some heart implants.
The idea addresses a problem that has followed pacemakers for decades. These devices can keep working only while they have enough power, and their batteries do not last forever. When the battery becomes depleted, patients may need another medical procedure.
A pacemaker helps people whose hearts beat too slowly or have certain abnormal rhythms. It sends carefully timed electrical signals that tell the heart muscle when to contract. Over the past 70 years, pacemakers have become dramatically smaller and smarter.
One important development has been the leadless pacemaker. Instead of placing a device under the skin of the chest and running wires into the heart, doctors can guide a tiny capsule through a vein in the leg and attach it directly inside the heart. These devices can reduce some problems associated with traditional pacemaker wires and chest implants.
The Micra leadless pacemaker, introduced commercially in 2016, is roughly the size of a large vitamin capsule. Yet a large share of its space and weight is still devoted to its battery. That battery generally lasts about seven to 10 years.
Replacing a leadless pacemaker is not always simple because it sits inside the heart. In some cases, an expired device may remain there while a new pacemaker is added. For someone who needs heart pacing from a relatively young age, repeated replacements could become an important long-term issue.
Researchers have therefore been looking for ways to create power inside the body. Some experimental systems use pressure, stretching or friction to generate tiny amounts of electricity. The difficulty is producing enough dependable power while keeping the generator small enough for an implant.
Pengfei Chen, a postdoctoral scholar in materials science and engineering at the University of Wisconsin–Madison, and colleagues developed a generator specifically with those limits in mind. Professor Xudong Wang oversaw the work. The study appeared in the Aug. 19, 2026, issue of Science Advances.
Rather than building a larger pacemaker around their generator, the researchers tried to fit the new power system into the battery space of an existing Micra device. They created tiny moving structures that sit around the pacemaker’s electronic parts. These structures contain surfaces that develop opposite electrical charges.
As the heart moves, the structures are squeezed and released. The charged surfaces come together and separate, producing electricity from the repeated motion. Some of that power can be used immediately, while some can be stored for later use.
The engineering challenge was enormous because the parts must be both flexible and durable. A human heart beats around 100,000 times on a typical day, meaning an implanted generator could experience hundreds of millions of movements over many years. A design that works briefly in a laboratory would not be enough.
In laboratory tests, the generator produced 276.6 microwatts per cubic centimeter. The researchers said this was sufficient to operate the pacemaker and represented a major improvement in power output compared with previous small generators based on similar ideas. The design is also relatively inexpensive to make, according to the team.
The next question was whether it could work in a living heart. Researchers implanted a prototype in a pig and followed its performance for one month. During testing, electricity from the generator successfully supported the stimulation needed to pace the heart.
The team also examined how the animal’s body responded to the implant. They reported no adverse reaction beyond what would be expected with a conventional battery-powered leadless pacemaker. This provided an early sign that the design could be compatible with living tissue.
However, the experiment also revealed an important weakness. The generator did not produce as much power inside the animal as it did under laboratory conditions. Heart muscle is soft, so some of the movement was absorbed instead of being transferred efficiently to the generator.
The shape of a heartbeat creates another challenge. The heart contracts with a complex squeezing and twisting motion rather than the simple straight movement that produces the generator’s highest output. Chen and Wang are now working on ways to convert this irregular motion into more useful movement inside the device.
From a medical perspective, the potential benefit is easy to understand. Dr. Daniel Modaff, a heart-rhythm specialist and co-author of the study, noted that replacing a pacemaker generator after a battery runs out requires another procedure. A reliable self-powered device could potentially remove that problem.
The research is an important engineering advance, but it should not yet be described as a lifetime pacemaker for humans. The animal test lasted only one month, and the device still needs to produce stronger and more stable power inside a beating heart. Researchers will also need much longer studies before they can know how well the moving parts survive years of constant use.
There are also questions that only future clinical studies can answer, including whether the device remains safe, whether scar tissue changes its performance and whether it can reliably power a pacemaker under different heart rates and levels of physical activity. Commercial use is therefore likely to be years away.
Even with those limits, the study points toward a fascinating future for medical implants. If engineers can reliably collect energy from normal body movement, future heart devices may need smaller batteries or perhaps no conventional battery at all. The same idea could eventually provide power for sensors and other implanted technologies that continuously watch or treat the heart.
Source: University of Wisconsin–Madison.
