Hydrophobic surface allows self-cleaning: sacred lotus
Leaves of the sacred lotus are self-cleaning thanks to nanoscale bumps.
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Lotus leaves, for example, exhibit extensive folding (i.e., papillose epidermal cells) and epicuticular wax crystals jutting out from the plant's surface, resulting in a roughened microscale surface. As water and air adhere less well than water and solids, roughened surfaces tend to reduce adhesive force on water droplets, as trapped air in the interstitial spaces of the roughened surface result in a reduced liquid-to-solid contact area. This allows the self-attraction of the polar molecule of water to express more fully, causing it to form spheres. Dirt particles on the leaf's surface stick to these droplets, both due to natural adhesion between water and solids and because contact with the leaf surface is reduced by over 95% from the leaf's micro-topography. The slightest angle in the surface of the leaf (e.g., caused by a passing breeze) then causes the balls of water to roll off due to gravity, taking the attached dirt particles with them and cleaning the leaf without using detergent or expending energy.
Surface finishes inspired by the self-cleaning mechanism of lotus plants and other organisms (e.g., many large-winged insects) have now been applied to paints, glass, textiles, and more, reducing the need for chemical detergents and costly labor.
Nelumbo nucifera Gaertn.
IUCN Red List Status: Unknown
Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist
Application Ideas: Self-cleaning, water-repellent surfaces
Industrial Sector(s) interested in this strategy: Buildings, manufacturing, automobiles, kitchen and bath, textilesLotusan® paint - Self-cleaning coating
GreenShield™ fabric finish - Multifunctional finishes for textiles
Lotus clay roofing tiles - Roofing tiles
Mincor® TX TT textile coating - A self-cleaning coating for textiles
Miniaturized condensers - Condenser
Wilhelm Barthlott Christoph Neinhuis (Institut für Botanik) Holger F. Bohn
Nees-Institut für Biodiversität der Pflanzen