Although humidity variation is a ubiquitous natural phenomenon with a great potential for energy sources, its exploitation is only in the infant stage. Hygroresponsive soft materials, either artificial or natural, can convert environmental humidity directly into mechanical motions, as mundanely observed in the curling of wet paper, swelling of kitchen sponges, the opening of pine cones, and self-burrowing of Erodium and Pelargonium seeds. Such hygroresponsive actuation relies on the diffusion of water molecules into soft absorbent materials that swell in a fashion designated by external mechanical constraints. This talk will introduce various soft actuation systems capable of bending, twisting, crawling, and rolling, which are built of aligned nanofiber meshes for effective moisture uptake and rapid mechanical response. We also demonstrate how mechanistic and thermodynamic models can lead to optimal designs for maximum speed or efficiency of soft actuation systems.
About the Speaker
Ho‑Young Kim received his B.S. degree from Seoul National University and M.S. and Ph.D. degrees from MIT, all in mechanical engineering. After a post-doctoral stint at Harvard University, he joined Seoul National University as a faculty in 2005, where he is now a professor of mechanical engineering. His research activities revolve around the mechanics of microfluids and soft matter, soft robotics, and biomimetics. He has been a Fellow of the American Physical Society since 2017.