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Built by a team of engineers led by the University of Massachusetts (UMass) Amherst with colleagues from the Massachusetts Institute of Technology (MIT), the bioelectronic mesh system can simultaneously measure both the electrical signal and the physical movement of cells in lab-grown human cardiac tissue.
Described as a “research first” in a UMass Amherst announcement, the system’s ability to grow alongside cells allows researchers to observe how the heart’s mechanical and electrical functions change during the developmental process.
The device could aid study of cardiac disease and the potentially toxic side effects of drug therapies, the researchers said. Ways of effectively monitoring living cardiac tissue are “extremely limited”, the announcement said, because it is very risky to implant sensors in a living heart and because it is a complex organ with multiple factors that need to be monitored.
“Cardiac tissue is very special,” says Jun Yao, associate professor of electrical and computer engineering and the paper’s senior author. “It has a mechanical activity – the contractions and relaxations that pump blood through our body – coupled to an electrical signal that controls that activity.”
The new device is built of two critical components. The first is a three-dimensional cardiac microtissue (CMT), grown in a lab from human stem cells.
The second critical component is graphene, a pure-carbon substance only one atom thick. Graphene is electrically conductive, so it can sense the electrical charges shooting through cardiac tissue. It is also piezoresistive, which means that as it is stretched – by the beating of a heart, for example – its electrical resistance increases. And because graphene is so thin, it can register the “tiniest flutter” of muscle contraction or relaxation, and can do so without impeding the heart’s function during the maturation process.
“Although there have already been many applications for graphene, it is wonderful to see that it can be used in this critical need, which takes advantage of graphene’s different characteristics,” said research co-author Jing Kong.
The team embedded a series of graphene sensors in a soft, stretchable porous mesh scaffold that has close structural and mechanical properties to human tissue, and which can be applied non-invasively to cardiac tissue.
“No one has ever done this before,” said lead author Hongyan Gao. “Graphene can survive in a biological environment without degrading for a very long time and not lose its conductivity, so we can monitor the CMT across its entire maturation process.”
The work was published in Nature Communications.
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