The tiny pacemaker sits next to a single grain of rice on a fingertip. The device is so small that it can be non-invasively injected into the body via a syringe.
John A. Rogers/Northwestern University
Engineers at Northwestern University have created a highly advanced, ultra-miniature pacemaker designed for injection via a syringe that is capable of dissolving harmlessly afterward.
This new device, designed for temporary pacing, is particularly useful for infants suffering from congenital heart defects as it provides a less invasive alternative when traditional pacemakers are needed.
The device is smaller than a grain of rice and can be paired with a soft, flexible, wireless wearable designed to be attached to the patient’s chest. The thermostatic device, when worn, monitors the heartbeat of the individual, and when an irregular heartbeat is detected, it emits a light pulse capable of piercing the skin and activating the pacemaker.
“We have developed what is, to our knowledge, the world’s smallest pacemaker,” said Northwestern bioelectronics pioneer John A. Rogers, who led the device development.
“Our major motivation was children,” added study co-lead Igor Efimov. “About 1% of children are born with congenital heart defects — regardless of whether they live in a low-resource or high-resource country. The good news is that these children only need temporary pacing after a surgery. Now, we can place this tiny pacemaker on a child’s heart and stimulate it with a soft, gentle, wearable device. And no additional surgery is necessary to remove it.”
A tiny, body-powered innovation
The most challenging part of shrinking the pacemaker even further was its power supply. The team redesigned the near-field communication-activated antenna system to a light-activated system, which greatly enhanced the effectiveness of the device while also drastically shrinking its size.
To make the device even smaller, the research team had to rethink how to power the device. Rather than using a battery, the pacemaker now works as a small galvanic cell that generates electrical pulses using two different metal electrodes and the biofluids of the body. The chemical reaction produces the electricity required, which then cathodes the heart, hence, stimulating it.
“When the pacemaker is implanted into the body, the surrounding biofluids act as the conducting electrolyte that electrically joins those two metal pads to form the battery,” Rogers said.
“A very tiny light-activated switch on the opposite side from the battery allows us to turn the device from its ‘off’ state to an ‘on’ state upon delivery of light that passes through the patient’s body from the skin-mounted patch.”
Expanding possibilities in medicine
The device uses infrared light, which penetrates deeply and safely into the body. When the wearable detects a dangerously low heart rate, it automatically triggers an LED to flash at a normal heart rhythm, activating the pacemaker accordingly.
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“The heart requires a tiny amount of electrical stimulation,” Rogers said. “By minimizing the size, we dramatically simplify the implantation procedures, we reduce trauma and risk to the patient, and, with the dissolvable nature of the device, we eliminate any need for secondary surgical extraction procedures.”
Due to the small size of these pacemakers, doctors could implant several devices in various locations around the heart and then turn them on separately using different colored lights. This may enable the treatment of other heart rhythms, including arrhythmias.
This advanced technology also has possible other uses under bioelectronics medicine like speeding up healing in nerves and bones, treating wounds, or blocking pain.
The study has been published in Nature.
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Srishti Gupta Srishti studied English literature at the University of Delhi and has since then realized it's not her cup of tea. She has been an editor in every space and content type imaginable, from children's books to journal articles. She enjoys popular culture, reading contemporary fiction and nonfiction, crafts, and spending time with her cats. With a keen interest in science, Srishti is particularly drawn to beats covering medicine, sustainability, gene studies, and anything biology-related.
