title: Wetting resistance at its topographical limit: the benefit of mushroom and serif T structures.
abstract: Springtails (Collembola) are wingless arthropods adapted to cutaneous respiration in temporarily rain-flooded habitats. They immediately form a plastron, protecting them against suffocation upon immersion into water and even low-surface-tension liquids such as alkanes. Recent experimental studies revealed a high-pressure resistance of such plastrons against collapse. In this work, skin sections of  Orthonychiurus stachianus  are studied by transmission electron microscopy. The micrographs reveal cavity side-wall profiles with characteristic overhangs. These were fitted by polynomials to allow access for analytical and numerical calculations of the breakthrough pressure, that is, the barrier against plastron collapse. Furthermore, model profiles with well-defined geometries were used to set the obtained results into context and to develop a general design principle for the most robust surface structures. Our results indicate the decisive role of the sectional profile of overhanging structures to form a robust heterogeneous wetting state for low-surface-tension liquids that enables the omniphobicity. Furthermore, the design principles of mushroom and serif T structures pave the way for omniphobic surfaces with a high-pressure resistance irrespective of solid surface chemistry.
authors.affiliation: Max Bergmann Center of Biomaterials, Leibniz Institute of Polymer Research Dresden, 01069 Dresden, Germany.
authors.forename: René
authors.initials: R
authors.lastname: Hensel
authors.forename: Ralf
authors.initials: R
authors.lastname: Helbig
authors.forename: Sebastian
authors.initials: S
authors.lastname: Aland
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Braun
authors.forename: Axel
authors.initials: A
authors.lastname: Voigt
authors.forename: Christoph
authors.initials: C
authors.lastname: Neinhuis
authors.forename: Carsten
authors.initials: C
authors.lastname: Werner
mesh_terms: D000818:Animals; D001181:Arthropods / Q000033:anatomy & histology* / Q000502:physiology*; D003198:Computer Simulation; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D000069463:Olive Oil; D010938:Plant Oils / Q000737:chemistry*; D013500:Surface Tension; D014867:Water / Q000737:chemistry*; D017155:Wettability
chemical_list: D000069463:Olive Oil; D010938:Plant Oils; D014867:Water