Exploring Dynamics and Dissipation on Superhydrophobic Surfaces with Magnetic Droplets
报告人：Dr. Robin H. A. Ras
Assistant Professor, Aalto University, Helsinki, Finland（email@example.com）
Aqueous droplets show a number of fascinating dynamical effects on superhydrophobic surfaces, including giant hydrodynamic slip and nearly frictionless motion and small roll-off angles. Quantification of the small but non-zero “friction” experienced by individual moving drops has proven to be challenging under well-controlled tangential and normal forces.
Here we present two different applications for ferrofluids on superhydrophobic surfaces. At first, we describe a new way for investigating dynamics and energy dissipation on superhydrophobic surfaces by using magnetic drops as probes. Secondly, strongly magnetic droplets can be split on a superhydrophobic surface into multiple droplets by applying a perpendicular magnetic field. The resulting daughter droplets self-assemble into various static and dynamic arrangements by applying magnetic fields.
 J. V. I. Timonen, M. Latikka, O. Ikkala, and R. H. A. Ras. Free-decay and resonant methods for investigating the fundamental limit of superhydrophobicity, Nature Communications 4, 2398 (2013)
 J. V. I. Timonen, M. Latikka, L. Leibler, R. H. A. Ras, and O. Ikkala, Switchable Static and Dynamic Self-Assembly of Magnetic Droplets on Superhydrophobic Surfaces, Science 341, 253-257 (2013)
Robin Ras is leading the Soft Matter and Wetting group at Aalto University, Helsinki, Finland. He obtained in 2003 a PhD degree in Bioscience Engineering–Chemistry from University of Leuven (Belgium). In 2004 he started as postdoc in the lab of Prof. Olli Ikkala. In 2013 he was appointed as Assistant Professor in the Department of Applied Physics. His research interests include water-repellent surfaces, fluorescent metal nanoclusters, responsive polymers, nanocellulose and aerogels.