a gecko-inspired chip-integrated reversible...

Kimberly Turner Associate ProfessorMechanical Engineering

Michael Northen, PostdocInstitute for Collaborative Biotechnologies

University of California, Santa Barbara

Kimberly Turner Associate ProfessorMechanical Engineering

Michael Northen, PostdocInstitute for Collaborative Biotechnologies

University of California, Santa Barbara

A Gecko-Inspired Chip-Integrated Reversible Adhesive

A Gecko-Inspired Chip-Integrated Reversible Adhesive

27 October 2006Slide 2 Turner and Northen

OutlineOutline• Introduction & Motivation• Gecko Adhesion Mechanism• Integrated Micro/Nanostructures

-adhesion testing• Adhesion Control

-adhesion testing

• Introduction & Motivation• Gecko Adhesion Mechanism• Integrated Micro/Nanostructures

-adhesion testing• Adhesion Control

-adhesion testing

Slide 3

Gecko Paper Frequency

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Slide 4

setaeE. Arzt & S. Gorb

Biology Nanoscience

MEMS & Nanotechnology

Biomimetics

Slide 5

Stanford Report, March 12, 2003

Mimicking cockroaches' 'mechanical intelligence'Development of legged robots could help in navigating disaster sites, other dangerous and difficult-to-reach places

BY BRONWYN BARNETT

Mark Cutkosky

Slide 6

“Fine hair” adhesive motif• Also found in other lizards and insects

– e.g. anoles, crickets, beetles, flies, spiders.

Slide 7

Adhesion MechanismAdhesion Mechanism

Slide 8

van der Waals

Short range London Dispersion Force

F = n H R / 6D2

H = Hamaker Constant (surface property)R = RadiusD = Cut-Off Distance (variable)n = Number of Contacts

Slide 9

S. Gorb

Arzt, Gorb, Spolenak PNAS 2003

Slide 10

Autumn, K., et al., PNAS, 99(19): p. 12252-12256 (2002). This hierarchical construction makes the lizard adhesive system elastically very soft on all relevant length scales (from mm to nm).

Persson and Gorb, J. Chem. Phys. (2003).

Multi-scale conformal structure

Slide 11

Controllable Conformance

Slide 12

“The use of a soft rather than solid base has dramatically (by nearly 1,000 times) improved gecko tape to support the weight of a suitably light familiar object(a toy in Fig. 4).”

Geim, A. K., Dubonos, S. V., Grigorieva, I. V., Novoselov, K. S. & Zhukov, A. A. Nature Materials 2, 461-463 (2003).

Slide 13

Controllable Conformance

Slide 15

Fabrication

27 October 2006Slide 16 Turner and Northen

27 October 2006Slide 17 Turner and Northen

27 October 2006Slide 18 Turner and Northen

27 October 2006Slide 19 Turner and Northen

27 October 2006Slide 20 Turner and Northen

Slide 21

Nanorod Properties

• Diameter ~ 200 nm• Length ~ 4 µm • Beta Keratin• Modulus ~ 1-15 GPa• High Density• No Condensation• Ultra-Hydrophobic,

Contact Angle ~170°

Courtesy Edward Arzt (S. Gorb)

27 October 2006Slide 22 Turner and Northen

Growing NanorodsGrowing Nanorods

E. Schäffer, Thrun-Albrecht, T., Russell, T.P., Steiner, U., Nature 403, 874 (2000).

27 October 2006Slide 23 Turner and Northen

Nanowire SynthesisNanowire Synthesis

V

27 October 2006Slide 24 Turner and Northen

Gecko Gecko

‘Organorods’‘Organorods’

Courtesy Edward Arzt (S. Gorb)

E = 6 GPa

E = 1-15 GPa

27 October 2006Slide 25 Turner and Northen

Nanorod PropertiesNanorod Properties• Diameter ~ 200 nm• Length ~ 4 µm • Beta Keratin• Modulus ~ 1-15 GPa• High Density• No Condensation• Ultra-Hydrophobic,

Contact Angle ~170°

• Diameter ~ 200 nm• Length ~ 4 µm • Beta Keratin• Modulus ~ 1-15 GPa• High Density• No Condensation• Ultra-Hydrophobic,

Contact Angle ~170°

Courtesy Edward Arzt (S. Gorb)

27 October 2006Slide 26 Turner and Northen

Contact AngleContact Angle

Hydrophilic 42.5°-OR-

Highly Hydrophobic 145°

Hydrophilic 42.5°-OR-

Highly Hydrophobic 145°

27 October 2006Slide 27 Turner and Northen

Adhesion TestingAdhesion Testing

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Northen, M. T., Turner, K.L. (2005). “Meso-scale adhesion testing of integrated micro-and nano-scale structures.” Sensors and Actuators A (In Press).

27 October 2006Slide 28 Turner and Northen

Slide 29

Adhesion Testing

Slide 30

Adhesion Comparison

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Slide 31

Durability Comparison

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Slide 32

Solid vs. Flexible

Damage vs. No Damage

Slide 33

Mimicked?

Coutesy Eduard Arzt (S. Gorb)

Gecko > 300 Pa (Adhesion)

90 kPa (Frictional Adhesion)

Synthetic < 30 Pa (Adhesion)

μ’ = Fadhesion / Fpreload

Geim et. al μ’ = 0.06

Northen & Turner μ’ = 0.125

Gecko μ’ = 8-15

Adhesion Control

Slide 36

Controllable Conformance

Slide 37

Ferromagnet in a magnetic field

Slide 38

Michael-Fabricated Gecko-Fabricated

Slide 39

Active Area

Support Substrate

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Slide 45

Basalt II Adhesion Tester

Test surface

Glass flat punch, D = 5 mm

Spring

Laser interferometer

PiezoMicro positioning stage

Slide 46

Basalt II Adhesion Tester

Slide 47

Glass Flat Punch Glass Flat Punch

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l-off

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Adhesion off (magnetic field present)

Adhesion on (magnetic field absent)

Preload (μN)

Adhesion S

trength (Pa)

Contact Pressure (Pa)

μ’ = 1.5

Slide 51

Synthetic vs. Gecko

μ’ = 1.5 μ’ = 8-15Fadhesion < 15 Pa Fadhesion > 300 Pa

Slide 52

The future:

Frictional Adhesion (more bio-inspiration)

Increased Packing Density

Integrated Magnetic Fields

AcknowledgementsAcknowledgementsFunding by:

ARMY Institute for Collaborative BiotechnologyAFOSR Structural Mechanics Program

Collaborators:

Eduard Arzt, Max Planck Institut, Stuttgart, GermanyJacob Israelachivili, UCSB

Turner Lab: Laura Oropeza, Weibin Zhang, Michael Requa, Abhishek Srivastava, Kari Lukes, Benedikt Zeyen, Mark Zielke, Barry DeMartini

‘Dude’

Funding by:

ARMY Institute for Collaborative BiotechnologyAFOSR Structural Mechanics Program

Collaborators:

Eduard Arzt, Max Planck Institut, Stuttgart, GermanyJacob Israelachivili, UCSB

Turner Lab: Laura Oropeza, Weibin Zhang, Michael Requa, Abhishek Srivastava, Kari Lukes, Benedikt Zeyen, Mark Zielke, Barry DeMartini

‘Dude’

For More Information:

www.engr.ucsb.edu/~tmems