Harvard and Manchester pioneer ’soft’ graphene-containing electrodes that adapt to living tissue

Researchers from The University of Manchester and Harvard University have collaborated on a pioneering project in bioengineering, producing metal-free, hydrogel electrodes that flex to fit the complex shapes inside the human body. The study , led by Harvard's Wyss Institute for Biologically Inspired Engineering in collaboration with the Laboratory of Soft Biolectronic Interfaces at EPFL in Lausanne and Manchester's National Graphene Institute (NGI), mixed carbon nanotubes with a water-based, defect-free solution of graphene, originally developed at the NGI by a team led by Professor Cinzia Casiraghi. Electrodes are frequently used in medicine to monitor or deliver electrical impulses inside and outside the human body, however performance is currently limited by the rigidity of devices that do not match the soft springiness of living tissue, a property known as viscoelasticity. Electrodes may detach under movement or require greater current to affect their intended target because their shape does not fit precisely to the host site. The key, according to lead authors Ms Christina Tringides and Professor David Mooney from Harvard, was a hydrogel that could mimic the viscoelasticity of tissue, alongside a conductive ink that could also perform well under flexion. Replacing rigid metals. Tringides and Mooney, in collaboration with the Nanomedicine Lab in Manchester, identified a mixture of graphene flakes and carbon nanotubes as the best conductive filler, replacing the use of traditional rigid metals.