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Carbon-Nanotube-Based (Gecko-Inspired) Adhesives

Carbon-Nanotube-Based (Gecko-Inspired) Adhesives. Bryan Schubert March 3, 2008. Gecko Adhesion. Notable features Strength: 10 N/cm 2 from van der Waals forces Reusable: 30 days between molts Directional Adheres to most surfaces; smooth or rugged Self-cleaning.

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Carbon-Nanotube-Based (Gecko-Inspired) Adhesives

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  1. Carbon-Nanotube-Based (Gecko-Inspired) Adhesives Bryan Schubert March 3, 2008

  2. Gecko Adhesion • Notable features • Strength: 10 N/cm2 from van der Waals forces • Reusable: 30 days between molts • Directional • Adheres to most surfaces; smooth or rugged • Self-cleaning 1. K. Autumn et al., J. Exper. Biol. 209, 3569 (2006).

  3. 50 μm 5 μm 1 μm Gecko Adhesion • Basic principle of operation – Contact splitting • Density of contacts scales by contact radius as N ~ R-2 • Force per contact scales as F ~ R-1 (JKR: F = 3πRW) • Force per unit area scales as FN ~ R-1 1. K. Autumn et al., J. Exper. Biol. 209, 3569 (2006).

  4. Oxygen plasma etch 5 μm 1 μm Top view Carbon Nanotube Adhesives - Fabrication • Vertically-aligned multi-walled carbon nanotubes (VA-MWNTs) • Chemical vapor deposition (CVD) on silicon substrate using thin film iron as catalyst layer and aluminum film as adhesion layer2,3. Diameter: 20-30 nm Length: 5-100 μm Density: 1010-1011 cm-2 2. L. Delzeit et al., J. Phys. Chem. B 106, 5629 (2002). 3. L. Delzeit et al., J. Phys. Chem. B 106, 5629 (2002).

  5. Carbon Nanotube Adhesives - Fabrication • Vertically-aligned single-walled carbon nanotubes (VA-SWNTs) • Plasma-enhanced CVD on SiO2/Si wafer with iron layer as catalyst and pre-coated aluminum adhesion layer. Fast heating4 was used to minimize catalytic particle aggregation, creating single-walled carbon nanotubes. Nanotube diameter: 2-3 nm Bundle diameter: 20-30 nm Length: 5-100 μm Bundle density: 1011 cm-2 4. Y. Q. Xu et al., J. Am. Chem. Soc. 128, 6560 (2006).

  6. glass 4 mm2 Si 5 mm2 parylene 7 mm2 glass 6 mm2 Au 4 mm2 GaAs 7.8 mm2 Adhesion Strength (N/cm2) Attachment Cycle Carbon Nanotube Adhesives - Performance • VA-MWNTs 5. Y. Zhao et al., J. Vac. Sci. Technol. B 24, 331 (2006).

  7. 4 mm x 4 mm Before use After use Carbon Nanotube Adhesives - Performance • VA-SWNTs • Normal Adhesion: 12-29 N/cm2 • Shear Adhesion: 4-16 N/cm2 • Performance decreases with use 6. L. Qu and L. Dai, Adv. Mater. 19, 3844 (2007).

  8. 4.70 N 0.01 N Carbon Nanotube Adhesives - Performance • VA-SWNTs • Mostly semi-conducting nanotubes 4 mm x 4 mm 6. L. Qu and L. Dai, Adv. Mater. 19, 3844 (2007).

  9. Comparison 7. S. Sethi et al., Nano Lett., 10.1021/nl0727765 (2008).

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