Engineers at Northwestern University have unveiled what may be the smallest pacemaker ever created—a rice-grain-sized, fully dissolvable device designed to be injected directly into the body through a syringe. This soft, wireless innovation is specifically tailored for temporary use in patients who require short-term pacing, such as infants recovering from congenital heart defect surgeries.
The pacemaker works in tandem with a soft, wearable patch worn on the chest. This patch continuously monitors the patient’s heartbeat and emits an infrared light pulse when it detects an irregular rhythm. The light safely penetrates the skin and activates the implant to stimulate the heart.
John A. Rogers, who led the device development, described the breakthrough as a major step forward in minimally invasive medical technology. According to Rogers, the dissolvable implant reduces the trauma and complexity typically associated with pacemaker removal, especially in young children.
Co-lead researcher Igor Efimov emphasized the urgent need for such technology, especially for the 1% of infants born with congenital heart defects worldwide. “These children only need temporary pacing after surgery,” Efimov explained. “This system removes the need for a second surgery by dissolving on its own once it’s no longer needed.”
Unlike conventional battery-powered implants, this pacemaker generates power internally using a galvanic cell—two different metal electrodes react with the body’s natural biofluids to produce the electricity needed to stimulate the heart. An ultra-small, light-activated switch on the device allows external control via the skin-mounted wearable.
The wearable patch uses infrared light, chosen for its ability to safely penetrate deep into body tissue. When the heart rate dips too low, the patch flashes an LED at a normal rhythm to activate the implant. The heart only requires a minimal electric pulse to reset, so the power demands of the system are low.
In addition to pacing, the miniaturized format opens the door to more complex therapeutic strategies. Multiple devices could potentially be implanted in various heart regions and selectively triggered with different light wavelengths, allowing for treatment of more intricate arrhythmias.
Researchers also see potential in expanding the technology beyond cardiology. Future applications in bioelectronic medicine could include nerve regeneration, pain modulation, wound treatment, or bone healing—all without the need for surgical extraction.
The full study appears in Nature.
