A research team led by Northwestern University and the University of Texas at Austin (UT) has developed a novel hair-thick graphene heart implant that uses light to monitor and modify abnormal heart rhythms.
Heart rhythm disorders (cardiac arrhythmias) are caused by abnormalities in the heart’s electrical signals, causing it to beat too fast or too slow. In some cases, it can lead to heart failure, stroke, and even sudden death.
Arrhythmias are usually treated with implanted pacemakers and defibrillators that monitor and correct abnormal rhythms. However, these devices are inflexible and can bind 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 pacemaker made from the strong, lightweight, biocompatible “supermaterial” graphene, and is the thinnest yet. Unlike existing implantable pacemakers and defibrillators, this one is molded to the heart tissue and strong enough to withstand the rigors of a beating heart.
“One of the challenges with current pacemakers and defibrillators is that they are difficult to attach to the surface of the heart,” said senior author Igor Efimov of the study. “Defibrillator electrodes, for example, are essentially coils of very thick wires. In contrast, our soft, flexible device is not only discreet, but also fits seamlessly and snugly directly over the heart, providing more accurate measurements.”
Researchers at UT had already developed graphene electronic tattoos with sensing capabilities that attach to the skin to continuously monitor vital signs such as blood pressure and electrical activity. In the current study, researchers used his UT’s electronic tattoo design to develop a device that works inside the body.
First, the e-tattoo was wrapped in a flexible silicone membrane, on which a gold tape about 10 microns thick was placed. Gold serves as an electrical connection between graphene and the electronics used to measure and stimulate the heart. The overall device thickness was approximately 100 microns. For context, the average human hair is about 70 microns thick.
Researchers tested the device on rats and found that it could accurately sense arrhythmias and deliver electrical stimulation without restricting the heart’s natural movements. was stable for 60 days. This is about the same time that temporary pacemakers are used as bridges to permanent pacemakers.
What’s more, the device’s transparency offers even more advantages, say researchers who used light to monitor and control the heart rhythm of rat subjects (electrocardiography). Photostimulation is a more precise method of correcting arrhythmias than electrical stimulation, using light to track specific enzymes and allow interrogation of heart, nerve, and muscle cells.
“Essentially, we can combine electrical and optical functions in one biointerface,” says Efimov. “Graphene is optically transparent, so you can actually read through it, allowing for much higher density readings.”
Researchers say using light in this way could provide new ways to diagnose and treat heart conditions.
The study will be published in the journal on April 20, 2023. advanced materials.
Source: Northwestern University
