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The wise man warns me that life is but a dewdrop on the lotus leaf - Tagore

The wise man warns me that life is but a dewdrop on the lotus leaf - Tagore. Biomimicry of the Lotus Effect . By – Ankit Modi Parag Surana . The Idea. Lotus leaf has a remarkable self cleaning effect due to its superhydrophobic surface.

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The wise man warns me that life is but a dewdrop on the lotus leaf - Tagore

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  1. The wise man warns me that life is but a dewdrop on the lotus leaf - Tagore

  2. Biomimicry of the Lotus Effect By – Ankit Modi Parag Surana

  3. The Idea • Lotus leaf has a remarkable self cleaning effect due to its superhydrophobic surface. • It is free of dust and also of contamination from microbes. • It has inspired many attempts to mimic the self cleaning effect by man-made materials. • Few examples – the lotusan® paint, bioseperation, snow removal, anti fogging surfaces. • It could throw the whole detergent industry out of business !!!

  4. Orientation • The physical basis. • Structural properties of lotus leaf at micro and nano level. • The mechanism of self cleaning. • Few examples of similar kind in other body designs. • Biomimetics of lotus effect

  5. Physical Basis – Surface Tension • Causes the suface layer of liquid to behave as an elastic sheet. • Bulk – A Molecule is pulled equally in all directions by neighboring liquid molecules. Net force = 0 • Surface – The inward force of molecular attraction is balanced by the resistance to compression. • Tendency to minimize surface energy by reducing surface area.

  6. Contact Angle • cos θ = (σs – γsl)/ σl • If (σs – γsl) is larger than σl, the drop tends to spread, i.e. θ = 0° • If (σs – γsl) is a lot smaller than σl, the drop is spherical, i.e. θ = 180°.

  7. Sliding Angle • The minimum angle (Θ) of the surface tilt, for the drop to flow. • Θ = (Θa –Θr) • The flow of drops is determined by the sliding angle. • Sliding angle of lotus leaf = 2-4o !

  8. Lotus Leaf Surface

  9. Bar = 20 μm

  10. Facts • Contact Angle - 161.0 ± 2.7° • Sliding Angle – 2 to 4o • The papillae is made of epicuticula wax. • Nano fibres on the papillae

  11. Self Cleaning Effect The decreased contact area between a particle and a rough surface. Particle is cushioned by air. Decreased contact area between liquid and surface and air is enclosed. Particles adhere to the surface of the droplet and are removed from the leaf when the droplet rolls off.

  12. Mechanism

  13. Points to remember… • Very small interfacial area between particle and rough surface. • Adhesion is minimized. • Particle is ``captured'' by the water droplet and removed from the leaf. • Leaf surface is not only free from dust but also free of contamination from microbes.

  14. Similar surfaces in Nature • Water Striders also have the typical micro and nano level hierarchy to produce high contact angles. • The dimple generates the tensile force to balance the weight. • Other examples – rice leaf, wings of cicada.

  15. Biomimetics of the Lotus Effect The Process Nano particles TiO2 surface

  16. The Results!!! Lotusan Paint Self Cleaning Textile

  17. Thank You

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