![\"\"](\"https:\/\/www.europesays.com\/uk\/wp-content\/uploads\/2025\/04\/worlds-smallest-pacemaker-on-finger-credit-Credit-John-Rogers-Northwestern-University-press-release-.jpeg\")
World\u2019s smallest pacemaker next to a grain of rice \u2013 Credit: John Rogers \/ Northwestern University press release<\/p>\n World\u2019s smallest pacemaker next to a grain of rice \u2013 Credit: John Rogers \/ Northwestern University press release<\/p>\n
Northwestern University engineers have developed a pacemaker so small that it can fit inside the tip of a syringe and be non-invasively injected into the body, according to a new study published in Nature.<\/p>\n
Although it can work with hearts of all sizes, the pacemaker is particularly well-suited to the tiny, fragile hearts of newborn babies with congenital heart defects.<\/p>\n
A pacemaker is an implantable device that helps maintain an even heart rate, either because the heart\u2019s natural cardiac pacemaker provides an inadequate or irregular heartbeat, or because there is a block in the heart\u2019s electrical conduction system.<\/p>\n
Smaller than a single grain of rice, the pacemaker is paired with a small, soft, flexible, wireless, wearable device that mounts onto a patient\u2019s chest to control pacing. When the wearable device detects an irregular heartbeat, it automatically shines a light to activate the pacemaker.<\/p>\n
These short light pulses, which penetrate through the patient\u2019s skin, breastbone, and muscles, control the pacing.<\/p>\n
Designed for patients who only need temporary pacing, the pacemaker simply dissolves after it\u2019s no longer needed. All the pacemaker\u2019s components are biocompatible, so they naturally dissolve into the body\u2019s biofluids, bypassing the need for surgical extraction.<\/p>\n
The paper demonstrates the device\u2019s efficacy across a series of large and small animal models as well as human hearts from deceased organ donors.<\/p>\n
\u201cWe have developed what is, to our knowledge, the world\u2019s smallest pacemaker,\u201d said John A. Rogers, PhD, professor of Neurological Surgery, Dermatology, and in the McCormick School of Engineering, who led the device development.<\/p>\n
\u201cThere\u2019s a crucial need for temporary pacemakers in the context of pediatric heart surgeries, and that\u2019s a use case where size miniaturization is incredibly important. In terms of the device load on the body\u2014the smaller, the better.\u201d<\/p>\n
\u201cOur major motivation was children,\u201d said<\/a> Igor Efimov, PhD, professor of Medicine in the Division of Cardiology and in the McCormick School of Engineering, who co-led the study.<\/p>\n \u201cAbout 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. In about seven days or so, most patients\u2019 hearts will self-repair. But those seven days are absolutely critical. Now, we can place this tiny pacemaker on a child\u2019s heart and stimulate it with a soft, gentle, wearable device. And no additional surgery is necessary to remove it.\u201d<\/p>\n This work builds on a previous collaboration between Rogers and Efimov, in which they developed the first dissolvable device for temporary pacing. Many patients require temporary pacemakers after heart surgery \u2014 either while waiting for a permanent pacemaker or to help restore a normal heart rate during recovery.<\/p>\n For the current standard of care, surgeons sew the electrodes onto the heart muscle during surgery. Wires from the electrodes exit the front of a patient\u2019s chest, where they connect to an external pacing box that delivers a current to control the heart\u2019s rhythm.<\/p>\n When the temporary pacemaker is no longer needed, physicians remove the pacemaker electrodes. Potential complications include infection, dislodgement, torn or damaged tissues, bleeding, and blood clots.<\/p>\n \u201cThat\u2019s actually how Neil Armstrong died,\u201d Efimov said. He had a temporary pacemaker after a bypass surgery. When the wires were removed, he experienced internal bleeding.\u201d<\/p>\n ADVANCES TO GET YOU EXCITED: <\/strong>Tiny Implantable Sensors Helped Broken Bones Heal in Weeks Rather Than Months<\/a><\/p>\n In response to this clinical need, Rogers, Efimov, and their teams developed their first dissolvable pacemaker, which was introduced in Nature Biotechnology in 2021. The thin, flexible, lightweight device eliminated the need for bulky batteries and rigid hardware, including wires.<\/p>\n To help further reduce the device\u2019s size, the researchers also reimagined its power source. Instead of using near-field communication to supply power, the new, tiny pacemaker operates through the action of a galvanic cell, a type of simple battery that transforms chemical energy into electrical energy. Specifically, the pacemaker uses two different metals as electrodes to deliver electrical pulses to the heart. When in contact with surrounding biofluids, the electrodes form a battery. The resulting chemical reactions cause the electrical current to flow to stimulate the heart.<\/p>\n \u201cWhen 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,\u201d Rogers said. \u201cA very tiny light-activated switch on the opposite side from the battery allows us to turn the device from its \u2018off\u2019 state to an \u2018on\u2019 state upon delivery of light that passes through the patient\u2019s body from the skin-mounted patch.\u201d<\/p>\n