A group of scientists developed a method to produce a hydrogel with superb conductivity without losing the characteristics that make it useful in biomedical applications. They published their findings in the science journal: Nano Letters.
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Hydrogels hold a wide variety of mechanical characteristics, making them useful in an enormous amount of applications. A considerable amount of variability in mechanical stiffness makes them particularly useful in biomedical applications like implants. (Implants need to match the mechanical characteristics of surrounding tissues). Aside from implants, another familiar example of the biomedical employment of hydrogels are soft contact lenses.
Some hydrogels are conductive, making them even more useful. They could, for example, be employed in sensors or assist in transmitting electrical signals in the body. An interdisciplinary research team at Kiel University in Germany has recently developed a way to create hydrogel with excellent conductive properties without it losing its medical compatibility. A hydrogel that is both elastic and conductive could be well-suited for implants used to treat certain brain diseases.
Margarethe Hauck, a materials scientist and one of the study's lead authors, explained in a press release that the elasticity of hydrogels could be accommodated to several types of tissue in the body and even to the consistency of brain tissue. According to her, this was one of the main reasons why they were interested in these hydrogels as implant materials.
Seen here is a tomography image of the conductive hydrogel as designed by the researchers. Each color signifies a linked microchannel. As the individual channels are heavily interlinked electrical signals can flow reliably through the whole material. - Image Credit: Berit Zeller-Plumhoff / HZG via EurekAlert/AAAS
Therefore, the interdisciplinary cooperation of materials and medical experts focuses on creating new materials that can be used for implants. Conductive hydrogels could, for instance, be applied to manage the release of active substances in order to treat certain brain diseases such as aneurysms, tumors, or epilepsy locally in a more targeted approach.
To make these conductive hydrogels, scientists use current-conducting nanomaterials made from high-tech materials such as graphene, carbon nanotubes, or gold nanowires. In the production process, there is a trade-off to be made between conductivity and elasticity. Using a higher density of the aforementioned nanomaterials results in better conductivity. However. this means that a sacrifice has to be made on flexibility and vice versa.
According to Christine Arndt, also a lead author of the study, cells are very sensitive to their environment. They are most at home with surrounding materials that mimic their properties as close as possible. One can safely assume that it is therefore imperative that at least some of the flexible properties from the hydrogel remain in the final product.
The research team has managed to find an ideal middle road when it comes to flexibility and conductivity. They opted to use graphene as their main conductivity component. Graphene boasts several benefits, among which its low mass, electrical and mechanical characteristics. Graphene consists of only one ultra-thin layer of carbon atoms meaning that significantly less material has to be used relative to the amount of hydrogel. The result is an amazing material with high conductivity and high elasticity.
The team opted to go with ultra thin graphene. Seen here is the hydrogel, streaked with microchannels of ultralight, electrically conductive graphene. - Image Credit: Irene Wacker via Eurekalert/AAAS
The researchers think that the interdisciplinary field of research that combines materials science with medicine will grow immensely in the coming years. Additionally, there is already some ongoing research with conductive hydrogel on biohybrid robots. The idea is to find a use for it in driving miniaturized robotic systems.
If you are interested in a more comprehensive overview of the study we covered in this article, be sure to check out the paper listed in our further reading section below.
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