Lotus leaves are inspiring new technology
Lotus leaves are very good at repelling water and dirt. Those attributes are leading scientists to develop new technologies that mimic the lotus leaf. For example, NASA is working on a coating for spaceflight gear that will repel dirt and bacteria. Duke University is working on creating lotus water repellant properties in man made materials while Georgia Tech has used the same properties for photovoltaic arrays and other technology.
NASA wants to reduce the collection of dust and dirt on spacesuits, vehicles and equipment used in space exploration. The dust and dirt damage the suits and equipment. Two different coatings will have to used since one will be needed for flexible materials like spacesuits and another for rigid equipment and moving parts.
Coatings already exist that are “made from silica, zinc oxide, and other oxides”. The coatings are used on windows and could be applied to “car windshields, camera lenses, and eyeglasses.” Unfortunately, the current coatings require modification for use in space. Adding a biocide to kill bacteria is also needed.
By adding a biocide to the coating, bacteria would be repelled as well reducing the chance that earth bacteria might be inadvertently transferred to other planets as well as cutting down on the stink factor. Bacteria that collects on surfaces such as those within the space station tends to thrive and become smelly. By coating the surfaces with a bacteria repelling substance, living in the cramped space station would be much more pleasant.
Meanwhile Duke University is looking into more earth bound uses for lotus leaf attributes.
…the lotus leaf has a surface roughness with "two-tiered" structures, the top tier made up of row after row of tiny hairy nanoscale pillars and the bottom tier made up of irregular microscale textures. As a result of nature’s design, droplets of water condensate and are held aloft from the actual leaf surface and are consequently extremely mobile, a phenomenon known as superhydrophobicity.
Duke engineer, Assistant Professor of Mechanical Engineering and Materials Science and director of Duke’s Microscale Physiochemical Hydrodynamics Laboratory, Chuan-Hua Chen has duplicated the lotus leafs “two-tier structure with carbon nanotubes on silicon posts.” The “engineered structure” was better at keeping surfaces dry.
The lotus leaf’s “superhydrophobicity has wide-ranging applications including self-cleaning materials, drag reduction, and water management.” Mimicking the lotus leaf’s superhydorphobicity also would “promote dropwise condensation and enhance heat transport in microelectronics cooling.”
Georgia Tech is developing the lotus leaf’s self cleaning ability for a variety of uses. A few examples are to help create more reliable electric transmission systems, and photovoltaic arrays that retain their efficiency”. C.P. Wong, a Regents Professor in Georgia Tech’s School of Materials Science and Engineering, and collaborators Yonghao Xiu, Lingbo Zhu and Dennis Hess, developed a coating made of “a combination of silicone, fluorocarbons, and inorganics such as titanium dioxide and silicon dioxide”. The coating has proved durable and able to withstand ultraviolet radiation. Other areas of “lotus” research are into improving implantable medical devices so that they repel blood cells to prevent clotting and “Application of lotus coatings to prevent “stiction,” which is the strong adhesive force that can form between the structures of micro-electromechanical systems (MEMS) and substrates. The magnitude of these forces can be enough to deform the structures, resulting in device failure.”
The lotus leaf is proving to be a wonderful template from which scientists are developing a wealth of useful technologies for improving life both here on earth and in outer space.
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