Nanostructured surfaces: bioinspiration for transparency, coloration and wettability

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Abstract

Natural nanostructures rarely come with a single biological function to fulfil. Moreover, from a bio-inspiration perspective, it sounds attractive to develop multifunctional coatings, devices or sensors. Suppression of light reflection from body parts, such as the wings of insects, is useful for hiding from predators. The transparent parts of the wings of Cacostatia ossa (moth) inherit their antireflective property from non-close-packed nano-scale nipple arrays on both sides of the wings. Through modelling and optical simulations, we show that effective medium approaches, commonly used to characterize antireflection, slightly overestimate the reflectance with respect to detailed Rigorous Coupled Wave Analysis calculation. Coloration due to light interference in nanostructure, on the other hand, sometimes comes with an additional, unexpected and maybe non-biologically significant function: hygrochromism, i.e. change of color with humidity. The male Hoplia coerulea (beetle), for instance, exhibits iridescent blue-violet color which turns to emerald green when the elytron is put in contact with water. Impregnation experiments with various liquids revealed intriguing color change dynamics which could be related to the wetting properties of porous chitinous cuticle. Super-hydrophobicity is another function of biological significance, which helps, for instance, insects to keep dry in humid environments. Through morphological, optical and contact angle measurements, we show the existence of entangled levels of functionality on the wings of Cicada orni, namely a superhydrophobic stage at the upper part of the nipple array corrugated surface and an antireflective stage and the lower part.
Original languageEnglish
Pages (from-to)122-129
Number of pages8
JournalMaterials Today Proceedings
Volume1S
DOIs
Publication statusPublished - 29 Dec 2014
EventLiving light 2014 - Namur, Belgium
Duration: 10 Apr 201412 Apr 2014

Keywords

  • Structural colors
  • antireflection coatings
  • hydrophobicity
  • optical sensors

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  • Projects

    Equipment

  • Morphology - Imaging

    Charles Nicaise (Manager) & Francesca Cecchet (Manager)

    Technological Platform Morphology - Imaging

    Facility/equipment: Technological Platform

  • Activities

    • 2 Participation in conference

    Third International Conference on Advanced Complex Inorganic Nanomaterials

    Sébastien Mouchet (Poster)

    13 Jul 201517 Jul 2015

    Activity: Participating in or organising an event typesParticipation in conference

    Living light 2014

    Sébastien Mouchet (Poster)

    10 Apr 201412 Apr 2014

    Activity: Participating in or organising an event typesParticipation in conference

    Student Theses

    Mécanismes fondamentaux de la coloration structurale : addiction et induction de couleurs

    Author: Mouchet, S., 29 Sep 2015

    Supervisor: Deparis, O. (Supervisor), Su, B. L. (Jury), Lepere, M. (President), Vukusic, P. (External person) (Jury), Berthier, S. (External person) (Jury) & Voué, M. (External person) (Jury)

    Student thesis: Doc typesDoctor of Sciences

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