Qin’s colleagues at Tsinghua University had previously developed a model to precisely simulate the interactions between atoms in graphene and water, using density functional theory - a computational modeling technique that considers the structure of an atom’s electrons in determining how that atom will interact with other atoms. “So we came up with a sandwich model for graphene, water, and membrane, that is a crystal clear system for seeing the thermal conductance between these two materials.” “In the body, water is everywhere, and the outer surface of membranes will always like to interact with water, so you cannot totally remove it,” Qin says. To do this, they considered the simplest interface, comprising a small, 500-nanometer-square sheet of graphene and a simple cell membrane, separated by a thin layer of water. The researchers sought to accurately characterize the way heat travels, at the level of individual atoms, between graphene and biological tissue. As a surface heats up, its atoms vibrate even more, causing collisions with other atoms and transferring heat in the process. These atoms are always vibrating, at frequencies that depend on the properties of their materials. Typically, heat travels between two materials via vibrations in each material’s atoms. Qin’s co-authors include Markus Buehler, head of CEE and the McAfee Professor of Engineering, along with Yanlei Wang and Zhiping Xu of Tsinghua University. “But sometimes we might want to intentionally increase the temperature, because for some biomedical applications, we want to kill cells like cancer cells. “We’ve provided a lot of insight, like what’s the critical power we can accept that will not fry the cell,” Qin says. The results are published today in the journal Nature Communications.Ĭo-author Zhao Qin, a research scientist in MIT’s Department of Civil and Environmental Engineering (CEE), says the team’s simulations may help guide the development of graphene implants and their optimal power requirements. They also identified the critical power to apply to the graphene layer, without frying the cell membrane. While direct contact between the two layers inevitably overheats and kills the cell, the researchers found they could prevent this effect with a very thin, in-between layer of water.īy tuning the thickness of this intermediate water layer, the researchers could carefully control the amount of heat transferred between graphene and biological tissue. Now, engineers from MIT and Tsinghua University in Beijing have precisely simulated how electrical power may generate heat between a single layer of graphene and a simple cell membrane. Because of this, any power applied to operate a graphene implant could precipitously heat up and fry surrounding cells. Graphene is composed of a single sheet of carbon atoms, linked together like razor-thin chicken wire, and its properties may be tuned in countless ways, making it a versatile material for tiny, next-generation implants.īut graphene is incredibly stiff, whereas biological tissue is soft. In the future, our health may be monitored and maintained by tiny sensors and drug dispensers, deployed within the body and made from graphene - one of the strongest, lightest materials in the world.
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