Graphene 'tattoo' helps researchers develop ultra-thin and flexible pacemakers

Device measures just 100 microns and can adjust to the heart’s delicate contours.
Jijo Malayil
Illustration of the implant on a human heart
Illustration of the implant on a human heart

Zexu Lin 

The thinnest known cardiac implant to date, and the first one made of graphene has been developed by a team of researchers from Northwestern University and the University of Texas in Austin.

Graphene is a two-dimensional supermaterial, which offers high strength, yet is lightweight, and displays conductive properties.

The implant resembles a kid's temporary tattoo and is thinner than a "single strand of hair yet still functions like a classical pacemaker," according to a statement by the team. 

Arrhythmia - or an irregular heartbeat - claims about 300,000 lives in the United States annually. Implantable pacemakers and defibrillators are used to detect abnormal heartbeats, and to regulate the rhythm with electrical stimulation. 

Most pacemakers and implanted defibrillators currently in use are made using rigid materials that are often incompatible with the human body. Due to their inflexible nature, the foremost challenge with current pacemakers and defibrillators is the difficulty of attaching them to the heart's surface, restricting the heart’s natural motion, and causing injuries to its soft tissues that may result in complications like painful swelling, perforations, blood clots and infections.

Size and flexibility make it an ideal implant

According to the team, the graphene implant "softly melds to the heart to simultaneously sense and treat irregular heartbeats".

As the implant is thin and flexible, it can adjust to the heart’s delicate contours as well as stretchy and strong enough to withstand the dynamic motion of a beating heart.

The device is "not only unobtrusive but also intimately and seamlessly conforms directly onto the heart to deliver more precise measurements," said Igor Efimov, the study’s senior author and professor at Northwestern. 

Graphene offers bio-compatibility

Researchers used an atomically thin form of carbon, known as graphene, which has the desired properties for use in many applications like high-performance electronics, high-strength materials and energy devices.

Graphene is bio-compatible as "carbon is the basis of life, so it’s a safe material that is already used in different clinical applications. It also is flexible and soft, which works well as an interface between electronics and a soft, mechanically active organ,” said Efimov. 

The team has already developed graphene electronic tattoos (GETs) with sensing capabilities that attach to the skin to monitor the body’s vital signs. Researchers used this material and covered it with an elastic silicone membrane with a "hole punched in it to give access to the interior graphene electrode".

A gold tape serves as an electrical interconnect between the graphene and the external electronics used to measure and stimulate the heart. The total thickness of the device stands at just about 100 microns. 

Tests have shown that the device remains stable for 60 days on an "actively beating heart at body temperature, which is comparable to the duration of temporary pacemakers used as bridges to permanent pacemakers or rhythm management after surgery or other therapies."