A battery-free pacemaker powered by the motion of a beating heart could one day eliminate the repeated replacement surgeries faced by many patients with implanted cardiac devices. Researchers at the University of Wisconsin–Madison have developed an oscillating triboelectric nanogenerator designed to generate electricity inside a leadless intracardiac pacemaker, potentially allowing the device to operate for the patient’s entire lifetime. The technology converts the mechanical movement of the heart into electrical energy and, in early animal testing, successfully powered cardiac stimulation without producing complications beyond those associated with conventional battery-powered pacemakers.
The device was developed by Pengfei Chen, a postdoctoral scholar in materials science and engineering at UW–Madison, under the supervision of Professor Xudong Wang. Their research is reported in Science Advances on August 19, 2026. The team focused on a central challenge in implantable electronics: producing enough power in an extremely small volume. “For a device like this, it’s not just about producing energy. Power density is the most important part,” Wang says. “You need to get enough power in a small enough volume.” According to the researchers, their nanogenerator achieves a power output density roughly an order of magnitude greater than that of earlier miniature nanogenerators.
Pacemakers have changed dramatically since the first bulky systems were implanted roughly seven decades ago. Traditional transvenous pacemakers contain a battery-powered generator implanted beneath the skin of the chest and use electrical leads threaded through veins to stimulate the heart. Modern versions are smaller and more sophisticated, able to monitor cardiac rhythms and adjust stimulation automatically. In 2016, the introduction of the Micra leadless intracardiac pacemaker offered another major advance. Encased in a titanium shell about the size of a large vitamin capsule, the device can be delivered through a catheter inserted into the femoral vein and secured inside the right ventricle, avoiding both a chest incision and the long leads associated with conventional pacemakers.
The leadless design, however, creates a difficult long-term problem. More than half of the Micra device’s size and weight is associated with its battery, which typically lasts between seven and 10 years. Once the battery is depleted, removing a pacemaker from inside the heart can be challenging and potentially risky. In many cases, the inactive device is left in place while another pacemaker is implanted. For younger patients, who may require several replacements over a lifetime, the accumulation of multiple devices could complicate future treatment. A self-sustaining power source would address one of the most persistent limitations of leadless cardiac technology while also making it possible to develop smaller and more capable implants.
The UW–Madison team designed its nanogenerator to fit inside the battery compartment of a Micra pacemaker without increasing the overall dimensions of the implant. The system uses specialized oscillating structures positioned above and below the pacemaker’s central electronics package. Each oscillator contains paired electrode plates connected electrically to one another. One side is coated with copper, while the opposite side is covered with fluorinated ethylene propylene, or FEP, a polymer capable of holding a contrasting triboelectric charge. As the heart contracts and relaxes, the resulting motion compresses and releases the oscillators, repeatedly bringing the oppositely charged surfaces together and pulling them apart.
This contact-and-separation cycle produces electricity through the triboelectric effect. When two materials with different tendencies to gain or lose electrons touch, charge is transferred between their surfaces. Separating the materials creates a changing electric field that drives current through an external circuit. In the pacemaker prototype, the generated energy can be delivered directly to the electronics or stored temporarily in a small onboard capacitor. The approach differs from a conventional battery because it does not rely on a finite chemical fuel supply. Instead, it harvests mechanical energy that is continuously available as the heart beats.
Creating a structure capable of surviving millions of cycles inside the heart required extensive mechanical optimization. The oscillators had to be flexible enough to move with very small cardiac forces, yet stable enough to maintain their performance over long periods. The researchers adjusted the placement and width of conductive wires, the thickness of electrode plates and supporting substrates, and the balance between rigidity and elasticity. Their laboratory tests showed that the nanogenerator could produce 276.6 microwatts per cubic centimeter, a power density sufficient to operate the pacemaker and substantially higher than previously reported miniature piezoelectric and triboelectric systems. The result is particularly significant because cardiac implants must generate useful power while occupying only a few cubic centimeters or less.
The researchers then evaluated the system in a pig, whose cardiovascular anatomy and cardiac physiology make it an important model for translational heart-device research. A prototype was implanted and monitored for one month to assess both performance and biocompatibility. During functional testing, the nanogenerator supplied enough energy for cardiac stimulation, and the animals did not show adverse reactions beyond those observed with conventional battery-powered intracardiac pacemakers. The study involved collaboration among materials engineers, cardiovascular biologists, large-animal cardiac specialists and clinical electrophysiologists, including Bo Liu, Eric Schmuck and Daniel Modaff. Their combined expertise helped the team assess not only whether the device could generate power, but also whether its design was compatible with the biological and clinical realities of implantation.
The early results nevertheless reveal important engineering obstacles before human trials can be considered. The nanogenerator produced less power inside the pig’s heart than it did under laboratory conditions because soft cardiac tissue dampened the oscillator’s movement. In addition, the heart does not move only along a simple vertical axis. Its natural motion includes twisting and multidirectional deformation, whereas the prototype generates its maximum output when movement is more directly aligned with the oscillator. Wang and Chen are now working to capture irregular cardiac motion more efficiently and convert it into the controlled mechanical oscillation needed for reliable energy generation. The device has been registered with the Wisconsin Alumni Research Foundation, but commercialization and clinical deployment are expected to require years of further testing.
If those challenges can be overcome, the technology could influence more than pacemakers. A reliable, self-sustaining energy source might allow future cardiac implants to combine stimulation with continuous diagnostics, wireless communication or advanced therapeutic functions without requiring a large battery. For patients, the most immediate benefit would be the possibility of avoiding repeated procedures to replace depleted generators. For device designers, removing or reducing the battery could create additional space for sensors and electronics while lowering the size and weight of implants. The UW–Madison team’s prototype remains an experimental technology, but its ability to transform the heartbeat into usable electrical power marks a significant step toward implants that draw their energy directly from the body.
Subject of Research: A battery-free, self-sustaining leadless intracardiac pacemaker powered by an oscillating triboelectric nanogenerator.
Article Title: Self-Sustaining Leadless Intracardiac Pacemaker Powered by Triboelectric Nanogenerator
News Publication Date: 19-Aug-2026
Web References: https://doi.org/10.1126/sciadv.aef8903
References: Science Advances, “Self-Sustaining Leadless Intracardiac Pacemaker Powered by Triboelectric Nanogenerator,” DOI: 10.1126/sciadv.aef8903.
Image Credits: Joel Hallberg / UW–Madison
Keywords
Triboelectric nanogenerator, battery-free pacemaker, leadless pacemaker, intracardiac pacemaker, cardiac implants, biomedical engineering, energy harvesting, implantable electronics, heart-powered technology, nanotechnology, Science Advances, UW–Madison
