Inspired by Frog Skin, NCHU Developed Bioinspired Multifunctional Anti-Algae Coating and The Result Was Published in Top International Journal

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Dr. Han-Yu Hsueh, Associate professor at National Chung Hsing University(Right), and Ting-Lun Chen, PhD student at National Chung Hsing University(Left), develop the world’s first bioinspired anti-biofouling surface coatings.

The soft and slippery skin of frogs inspired the team of Associate Professor Han-Yu Hsueh from the Department of Materials Science and Engineering, National Chung Hsing University to research and develop a multi-functional bioinspired coating that can resist the adhesion of aquatic organisms. This coating inspired by frog skin is the first in the world and can be used in the future for multiple purposes such as anti-fouling on the surface of hulls, submarines and offshore oil tanks, anti-icing of aircraft, and self-cleaning of underwater optical equipment. The research results are published in the top journal "Advanced Functional Materials" in October and selected inside cover story.

Han-Yu Hsueh said that in addition to affecting the appearance of the equipment and causing damage to the surface structure, underwater fouling organisms have huge impacts on economy and environment. Take larger marine vessels as an example: once fouling organisms attach to the surface of submerged objects, the accumulation results in overloading which increases drag as well as causing extra fuel consumption. While vessels cruise worldwide, fouling organisms bring damages to not only ecological system by spreading and spawning as exotic invasion, but precision instruments if entering into interior portion. 

The study imitated the soft, wrinkled and slippery characteristics of the amphibian frog skin, inspired by observing the epidermal patterns of various native endemic species of frogs in Taiwan. The frog skin being magnified 30,000 times, the team found the surface of the mound-like protrusions is scattered with micron patterns of dots or grooves and others. These pores and grooves help store the mucus; therefore, the team concluded that anti-algae and anti-fouling effects of frog skin come from the multi-scale microstructure on the surface which stores and retains the mucus secreted by frog skin.

The team used the original polymer synthesis technology to create nanopores on the micron-level wrinkled surface, and infused the surface with lubricating fluid, such as silicone oil, to form a slippery surface that mimicked the skin of frog. The wrinkled curved surface is not conducive to the adhesion of algae because it is uneven, forming a structural anti-algae ability. Nanopores have strong capillary force and can absorb silicone oil to form a stable and long-lasting synovial surface, which prevents the synovial fluid from being quickly lost due to the impact of shear forces like ocean currents. This slippery surface makes biological fouling not easy to stick on and biological fouling desorb with the water flow, further strengthening the antifouling ability of the structured surface. At the same time, the tests in a dynamic environment and different algae species have proved that this kind of coating has the long-lasting ability to resist the adhesion of biological fouling, and can cope with diverse algae in different environments, such as the algae in freshwater and seawater.

The first author of this paper, Ting-Lun Chen, PhD student, is the main executor who is ingenious from experimental design to sample preparation. We are especially grateful to Professor Li-Feng Chien of National Chung Hsing University and Professor Wei-Lung Wang of National Changhua University of Education for providing algae, and Professor I-Ju Yang of National Dong Hwa University for providing frog samples. The research is a successful cross-field collaboration consists of local members.

Han-Yu Hsueh said that Taiwan is a subtropical island country with a humid climate and scattered freshwater ponds and lakes where algae grow easily. This study proposes effective anti-algae countermeasures, and is expected to help solve local people’s livelihood issues and social and environmental problems in Taiwan. In the future, the team will try to reduce material costs and technical thresholds. Starting from polymer materials, we will use interdisciplinary methods by integrating materials chemistry and interface science, regulate the type and composition of nano-hybrid materials, and further promote to the industry to eventually turn it into products.

NCHU research team applied the bioinspired anti-algae coating to the scuba masks(Right), which showed extraordinary result compared to the half without coating(Left) .

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