(182d) Elastocapillarity Pumps: Water Transport in Feathers

The optics, wettability and maneuverability of bird feathers are tuned at the microscale by barb and barbule structural arrays. In this work, we explore the water absorption and retention properties of bird feathers. By examining a bird species that survives in extreme environmental conditions, we will share how barbules act as responsive active materials that change shape and collective arrangement when hydrated. A mechanism for these fluid-responsive biological actuators is proposed that leverages multiscale hierarchical properties of barbules including keratin crystallinity (phase change), nanoscale grooves (capillarity) and helical structures (elastocapillarity mechanics). Our work has the potential to inform design of a new class of feather-inspired lightweight, responsive materials for water absorption from the environment.