A tiny artificial pacemaker that can be implanted via injection without incision has been developed. It is expected that multiple units can be attached to the heart's surface for precise treatment without surgical burden.
John Rogers, a professor of biomedical engineering and neurosurgery at Northwestern University in the United States, noted on the 3rd that his research team developed a tiny pacemaker that operates using light passing through the skin. The research findings were published in the international journal Nature. Research Institute Jeong Jin-hun and Professor Choi Jun-hwan of the University of Incheon were also listed as co-authors in the paper.
A pacemaker is an artificial device that delivers electrical stimulation to ensure the heart beats regularly. Typically, it is implanted under the chest skin and connected to wires sutured to the heart. However, during the process of replacing the pacemaker or wires through surgery, side effects such as bleeding and tissue damage may occur. In fact, Apollo 11 astronaut Neil Armstrong died from excessive bleeding during wire removal surgery.
The research team first introduced a coin-sized biodegradable artificial pacemaker in 2021. The first author of the paper published in Nature Biotechnology was Dr. Choi Yeon-sik. It was designed to naturally decompose and be absorbed by the body when its lifespan ends, eliminating the need for a secondary surgery for removal. Subsequently, the research team conducted studies to create even smaller pacemakers that could be used by young patients, making it possible to inject them through blood vessels instead of performing surgery.
To reduce the pacemaker's size, the research team chose a light-control method instead of wireless control using an antenna. When a wearable device attached to the skin detects irregular heartbeats, it sends infrared light to the heart. This activates the light-responsive switch in the tiny pacemaker, delivering electrical stimulation to the heart without the need for an additional battery. This is possible because the galvanic cell generates current on its own through the oxidation-reduction reaction of body fluids.
As the antenna required for wireless communication was removed, the pacemaker's dimensions were significantly reduced to 1.8 mm wide, 3.5 mm long, and 1 mm thick, which is smaller than a grain of rice. It can be injected into the body via injection without surgery and will dissolve naturally after use. The research team confirmed that the pacemaker operated stably for several days in experimental animals and in the hearts of brain-dead individuals before completely decomposing and being absorbed by the body.
This pacemaker can be placed in multiple locations on the heart and controlled independently with light of different wavelengths. This allows for more precise treatment of arrhythmias, which can alter or become irregular in heartbeat speed, by stimulating different areas of the heart with various rhythms, the research team explained.
Due to its small size, it can be easily consolidated with other implantable medical devices. Professor Rogers said, "The newly developed pacemaker is so small that it can be used with almost any type of implantable medical device," adding that "it can enhance performance by adding functions to existing devices."
References
Nature (2025), DOI: https://www.nature.com/articles/s41586-025-08726-4
Nature Biotechnology (2021), DOI: https://doi.org/10.1038/s41587-021-00948-x