Researching Biomimetic Applied Technology to Mimic Biological Functions

• published: 13 Apr 2015
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The Shiratori Laboratory of the Department of Applied Physics and Physico-Informatics of the Faculty of Science and Technology at Keio University is researching “biomimetics”, a technology that mimics superior biological functions, and applies those functions in production and technology development. "We often hear the term wet process in particular, but the research that we’re conducting in my lab is all based on water. Vacuum equipment and various types of specialty devices are used in industrial applications, but if we use living organisms as examples, various animals use absolutely no vacuum equipment whatsoever. In fact, they only use things that are gentle to the environment and that return to nature. We are looking very carefully at this area and using it as an example to create thin films without using any vacuum equipment whatsoever. In other words, we’re creating thin films using water. More specifically, we’re using water, air, and hydrocarbons. The basis of our research is to create thin films using only those materials that are used to form biological body." Biological designs, which were formed by adapting to harsh environments and evolving over a long period of time of hundreds of millions of years, have resulted in extremely superior functions. In order to utilize these superior designs in a useful manner in the lives of humans, Professor Shiratori is researching and mimicking those functions, and developing new technologies with minimal environmental burden. "When water falls on the surface of a lotus leaf, the water forms balls that roll off the leaf. If we observe that phenomenon with a microscope, we can see that the surface is covered with concave and convex shapes on both a micro-order and a nano-order, and when we observe those shapes in greater detail, we find out that the entire surface is made of hydrocarbons. If we artificially reproduce those hydrocarbons and attach them on top of glass, concrete, and paper, we can obtain glass, concrete, and paper that have the same type of properties as the lotus leaf. We’ve developed new types of thin films that can be used to apply this superhydrophobic phenomenon like that of the surface of a lotus leaf in various applications to impart a property that causes water to form into balls and roll off. " When a coating that mimics the thin film of a lotus leaf is applied to a drinking cup, carbonation in the cup becomes covered with a surface layer, making it more difficult for the carbonation to escape compared to the use of a conventional cup. In addition, when this function is applied to paper, paper that is not destroyed even when soaked in water can be achieved. In addition to the thin film of a lotus leaf, Professor Shiratori is also researching Nepenthaceae, a type of carnivorous plant. The surface of Nepenthaceae is covered with a liquid viscous film, and insects on which it has preyed slide to the bottom where the plant is able to absorb the nutrients. The research team anticipates that this property called slipping can be applied in various applications such as in ketchup containers to make it possible to squeeze out even the very last drop, and in paint and concrete that can be easily peeled away. By applying the unique characteristics of plants and animals in foods and products for everyday life in this manner, those characteristics can be utilized in a useful manner in the lives of humans. "In my lab, we’re using simple methods including “layer-by-layer” lamination using the Coulomb’s force of electric charges, and drawing out a liquid with a rod using what is called a squeegee method. In the dynamic terms of physics, it is becoming more and more important for us to develop technology that can be used to easily create strong, thin films by skillfully using forces such as electrostatic force, Vand der Waals’ forces, and the force of covalent bonds. Natural forces have a history of several tens of thousands to several hundreds of millions of years, so I’m impressed every day at how well those forces function."