title: Continuous directional water transport on the peristome surface of Nepenthes alata.
abstract: Numerous natural systems contain surfaces or threads that enable directional water transport. This behaviour is usually ascribed to hierarchical structural features at the microscale and nanoscale, with gradients in surface energy and gradients in Laplace pressure thought to be the main driving forces. Here we study the prey-trapping pitcher organs of the carnivorous plant Nepenthes alata. We find that continuous, directional water transport occurs on the surface of the 'peristome'--the rim of the pitcher--because of its multiscale structure, which optimizes and enhances capillary rise in the transport direction, and prevents backflow by pinning in place any water front that is moving in the reverse direction. This results not only in unidirectional flow despite the absence of any surface-energy gradient, but also in a transport speed that is much higher than previously thought. We anticipate that the basic 'design' principles underlying this behaviour could be used to develop artificial fluid-transport systems with practical applications.
authors.affiliation: School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China.
authors.forename: Huawei
authors.initials: H
authors.lastname: Chen
authors.affiliation: School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Zhang
authors.affiliation: School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China.
authors.forename: Liwen
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Laboratory of Bio-inspired Smart Interface Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Hongliang
authors.initials: H
authors.lastname: Liu
authors.affiliation: School of Chemistry and Environment, Beihang University, Beijing 100191, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: School of Mechanical Engineering and Automation, Beihang University, Beijing 100191, China.
authors.forename: Deyuan
authors.initials: D
authors.lastname: Zhang
authors.affiliation: Key Laboratory for Bionic Engineering, Ministry of Education, Jilin University, Changchun 130022, China.
authors.forename: Zhiwu
authors.initials: Z
authors.lastname: Han
authors.affiliation: Laboratory of Bio-inspired Smart Interface Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, China.|School of Chemistry and Environment, Beihang University, Beijing 100191, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Jiang
mesh_terms: D000818:Animals; D001692:Biological Transport; D032701:Biomimetics; D007313:Insecta; D019684:Magnoliopsida / Q000033:anatomy & histology* / Q000378:metabolism*; D019441:Plant Epidermis / Q000033:anatomy & histology / Q000378:metabolism; D013499:Surface Properties; D014867:Water / Q000378:metabolism*; D014872:Water Movements
chemical_list: D014867:Water