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A reversible wet/dry adhesive inspired by mussels and geckos

A reversible wet/dry adhesive inspired by mussels and geckos. H.Lee, B. P. Lee, P. B. Messersmith, Nature 2007 , 448, 338. 奈米科技概論 期中報告 授課老師 : 李旺龍 教授 學生 : 陳凌哲 N58961197. Outline. Introduction Experiment Results and discussion Conclusion Future work. Introduction.

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A reversible wet/dry adhesive inspired by mussels and geckos

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  1. A reversible wet/dry adhesive inspired by mussels and geckos H.Lee, B. P. Lee, P. B. Messersmith, Nature2007, 448, 338. 奈米科技概論 期中報告 授課老師:李旺龍 教授 學生:陳凌哲 N58961197

  2. Outline • Introduction • Experiment • Results and discussion • Conclusion • Future work

  3. Introduction • The function of any part of an animal results from its unique structure • Consider the gecko, a small lizard commonly found in the tropics • A gecko can walk up a wall and across ceilings • How does it do that?

  4. The explanation relates to hairs, called setae, on the gecko’s toes • They are arranged in rows • Each seta ends in many split ends called spatulae, which have rounded tips

  5. Gecko Tape • The ability to “stick” to surfaces results from attractions between molecules on the spatulae and molecules on the surface • The structure of the gecko’s feet leads to a unique function

  6. The wonder of the Gecko toes 2 kg (theoretically) 500000000 nanohairs Geckos get a grip using Van-der-Waals-forces Gecko sticking at the wall

  7. The seta has 1000 nanohairs The Gecko toe has 500000 microhairs (setae) Nanostructure of the Gecko toe

  8. The Gecko effect Technical surface 1 Adhesion effect through Van-der-Waals-forces Contact area Technical surface Technical surface 2 Nanohairs Small contact area small adhesion force Microhair Large contact area large adhesion force

  9. Gecko-Tape

  10. Experiment • Rational design and fabrication of wet/dry hybrid nanoadhesive

  11. Results and discussion • Fabricated gecko and geckel adhesives

  12. AFM method for adhesion measurement and imaging of contact

  13. Force adhesion strength of geckel

  14. Conclusions • Addition of p(DMA-co-MEA)coating on the pillars significantly increased wet/dry adhesion. • The pillars number indicates constructive force accumulation.

  15. Future work • Design of highly effective at adhering reversibly to surface . • Design of wet temporary adhesive for medical、industrial、consumer and military settings.

  16. Thanks for your attention.

  17. The Moth-Eye-Effect

  18. 130 x 420 x 1050 x 4120 x Micro-burls 100nmØ Micro-optics of the moth eye

  19. < l light Air Optical transparent layer Reflection of the light is avoided by a continuously increasing refractive index of the optical medium Glass Deception of the light The little burls on the surface of the optical medium work as a gentle increase of the refractive index

  20. All the light is captured by th eye Moonlight is not mirrored (predatory!) Night-flying insect

  21. Invisible Jelly Fish

  22. Technological imitation of the nanostructure of a moth eye. Periodicity of the burls: 300 nm. Glass pane with Moth-Eye-Effect

  23. The Moth-Eye-Effect

  24. The Sandfish lives in the Sahara desert ? The Sandfish-Effect

  25. Sandfish ? Fishing rod

  26. 0 s The Sandfish ¼ s ½ s dives down

  27. Characteristics of the sandfish scales M. Zwanzig, IZM Friction Abrasion sand flow Electron emission 8µm

  28. My Sahara Lab Field work in the Sahara GPS: N 31°-15‘–02“ W 03°-59‘–13“ Erg Chebbi

  29. Simple apparatus to measure the dynamic friction coefficient of flowing sand Sand tubule Angular scale Object platform Hand lever

  30. Measurement of the dynamic friction coefficient

  31. 20° Sand flow is moving 18° Sand flow stops Sandskink Measurement of the angle of sliding friction

  32. 0 40 0 35 0 30 sliding angle 0 25 n 0 20 o n d l f o n ss e l 0 a y T 15 a S N l teel k G n 0 10 i S k S Sahara-Measurement 2002 0 5 0 0 Sliding friction: Sandfish versus engineering materials

  33. Friction measurements with a sand-filled cylinder

  34. 58 % Sand-cylinder measurements 2003 Steel = 19° Sliding angle: Sandskink = 12° Caudal Sandskink = 18° Cranial

  35. 50nmØ Sandfish scale under the electron mikroscop (REM) scale Sand sflow 8µm at the back at th belly

  36. Sand flow 6µm Oblique view of the nano-thresholds

  37. Sliding direction Size comparison Grain of sand upon the thresholds

  38. Abrasion of the sandfish scales

  39. The sandskink always looks shiny while Man-made things soon get blunt in the desert wind ! The resistance to abrasion

  40. Simple apparatus for the abrasion tests Sandfunnel Sandblast Objectplatform

  41. Impact point of the sandblast Impact time: 10 hours ! Steel Abrasive spot: Glass

  42. Glass Magnification ≈200 Sand abrasion under the microscope 2 hours impact time 20 cm blast height Scotch tape protected Sand blast Sandfish Magnification ≈1000 Sandfish Magnification ≈1000 Afterward Before

  43. Kenyan Sandboa Sandskink Parallel Evolution

  44. Sandskink Kenyan Sandboa Sandskink Parallel Evolution

  45. Aporosaura anchita Sand-diving lizard in the Namib desert Namib

  46. The Mongolian Death Worm Allghoi khorkhoi lives in the Ghobi dersert ? Ghobi

  47. Electrical charging in a sand storm

  48. Night photo Exposure time 20 s Discharge spark on the back of the sandskink after a sand storm

  49. Triboelectric charging of a glass rod

  50. Triboelectric charging of a plastic rod

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