An interdisciplinary research team of the Research Training Group (RTG) 2154 "Materials for Brain" at Kiel University (CAU) has developed a method to produce graphene-enhanced hydrogels with an excellent level of electrical conductivity. What makes this method special is that the mechanical properties of the hydrogels are largely retained. The material is said to have potential for medical functional implants, for example, and other medical applications.

"Graphene has outstanding electrical and mechanical properties and is also very light," says Dr. Fabian Schütt, junior group leader in the Research Training Group, thus emphasizing the advantages of the ultra-thin material, which consists of only one layer of carbon atoms. What makes this new method different is the amount of graphene used. "We are using significantly less graphene than previous studies, and as a result, the key properties of the hydrogel are retained," says Schütt about the current study, which he initiated.

In order to achieve this objective, the scientists thinly coated a fine framework structure of ceramic microparticles with graphene flakes. Then they added the hydrogel polyacrylamide, which enclosed the framework structure, which was finally etched away. The thin graphene coating in the hydrogel remains unaffected by this process. The entire hydrogel is now streaked with graphene-coated microchannels, similar to an artificial nervous system.

Special 3D images by the Helmholtz-Zentrum Geesthacht (HZG) demonstrate the highly electronic conductivity of the channel system: "Due to a multitude of connections between the individual graphene tubes, electrical signals always find their way through the material and make it extremely reliable", says Dr. Berit Zeller-Plumhoff, Head of Department for Imaging and Data Science at HZG and an associate member in the RTG. With the help of high-intensity X-rays the mathematician took the images in a short time frame at the imaging beamline operated by the HZG at the storage ring PETRA III at the Deutsche Elektronensynchrotron DESY. And the three-dimensional network has yet another advantage: its stretchability enables it to adapt relatively flexibly to its environment.



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