The idea of rendering surfaces slippery when wet is known since antiquity. The ancient Egyptians poured water over sand to reduce solid-solid friction when transporting heavy blocks of stone across the dessert. More recently, the same basic idea—turning surfaces slippery when wet—was used to minimize and even eliminate solid-liquid friction, resulting in new classes of ultra-slippery, liquid-repellent surfaces. I will discuss strategies to design such surfaces inspired by examples in nature, especially the pitcher plant. Such surfaces can eliminate contact-line pinning on moving droplets (water and oil) and have many applications in the water-energy nexus (water-harvesting, anti-icing, and anti-fouling), biomedical devices (preventing blood clots), and making photonic crystals. In the final part of the talk, I will show some unpublished work showing how complex, emergent motion can arise spontaneously from condensing droplets on such surfaces.
Dan Daniel was born in Indonesia, but spent most of his formative years outside: first in Singapore, followed by undergraduate and postgraduate training in the UK (Cambridge, 2011) and the States (Harvard, 2017), before returning to Singapore first as a post-doc (2017-2020) and then as a group leader (2021-2022) at the Agency for Science, Research and Technology (A*STAR). His main research interests are in the physics of droplets, wetting/adhesion, and soft matter. He has authored and co-authored multiple papers in top journals, including Nature Physics, Nature Materials, PNAS, PRL, and PRX. More recently, he was awarded the IACIS Emerging Investigator Award 2022 and joined KAUST in Nov 2022 as an assistant professor.
Mechanical Engineering, King Abdullah University of Science and Technology