December 3, 2023

A team of researchers led by Northwestern University and The University of Texas at Austin (UT) has developed a new graphene heart implant about the thickness of a strand of human hair that uses light to monitor and correct abnormal heart rhythms.

Cardiac arrhythmias – arrhythmias – are caused by faulty electrical signals in the heart, causing the heart to beat too fast or too slow. In some cases, this can lead to heart failure, stroke, and even sudden death.

Arrhythmias are often treated with implanted pacemakers and defibrillators, which monitor and correct abnormal rhythms. But these devices are not flexible enough to compress the heart, causing tissue damage and discomfort and increasing the risk of complications such as swelling, perforation, blood clots and infection.

The new pacemaker is the first to be made from the strong, lightweight, biocompatible “supermaterial” graphene, and the thinnest to date. Unlike existing implantable pacemakers and defibrillators, the pacemaker shapes itself to the heart tissue while being strong enough to withstand the rigors of a beating heart.

“One of the current challenges with pacemakers and defibrillators is that they are difficult to attach to the surface of the heart,” said Igor Efimov, the study’s senior author. “For example, defibrillator electrodes are basically coils of very thick wires. These wires are not flexible and can snap. A rigid interface with soft tissue like the heart can lead to all kinds of complications. In contrast, we are soft, flexible The device is not only unobtrusive, but fits directly and seamlessly over the heart, providing more precise measurements.”

UT researchers are already developing a sensing-enabled graphene electronic tattoo that can adhere to the skin to continuously monitor vital signs such as blood pressure and electrical activity. For the current study, the researchers used UT’s e-tattoo design to develop a device that can operate inside the body.

They first wrapped the e-tattoo in a flexible silicon membrane, then placed a gold tape about 10 microns thick on top of it. Gold acts as an electrical link between the graphene and the electronics used to measure and stimulate the heart. All in all, the total thickness of the device is about 100 microns. For context, the average human hair is about 70 microns thick.

Graphene heart implants on tattoo paper
Graphene heart implants on tattoo paper

The researchers tested their device in mice and found that it could accurately sense arrhythmias and then deliver electrical stimulation without restricting the heart’s natural movement. It is stable on an actively beating heart at body temperature for 60 days, around the same time a temporary pacemaker is used as a bridge to a permanent pacemaker.

What’s more, the device’s transparency offers added advantages, say the researchers, who used light to monitor and control the heart rhythm (electrocardiogram) of their rat subjects. Light stimulation is a more precise method of correcting cardiac arrhythmias than electrical stimulation, and light can be used to track specific enzymes and study heart, nerve and muscle cells.

“We can basically combine electrical and optical functionality into one biological interface,” Efimov said. “Because graphene is optically transparent, we can actually read it, which gives us a higher read density.”

Using light in this way could provide a new way to diagnose and treat heart disease, the researchers say.

The study will be published in the journal on April 20, 2023 advanced materials.

source: Northwest University