Department of Applied Physics
University PhD Dissertation Defense
Force Space Studies of Elastomeric Anisotropic Fibrillar Adhesives
Daniel Ruben Soto
Research Advisor: Professor Thomas Kenny
26 May 2010 @ 3:30 P.M.
Allen Building (Formerly CIS-X), Room 101
ABSTRACT
Research into the climbing ability of the gecko lizard revealed an adhesive system fundamentally different from existing synthetic adhesives. Instead of using a soft material, the gecko uses a complex system of hairs of beta-keratin, a material that is not tacky. This unique architecture affords the adhesive characteristics that make it well suited for climbing.
Borrowing themes from the gecko, we developed a synthetic adhesive possessing similar properties using molded arrays of micron-scale silicone pillars. These arrays demonstrate the gecko property of frictional adhesion where increased shear stress at the interface leads to increased normal load capacity. To distinguish between intrinsic and emergent behavior, we also isolated single pillars to test on a dual-axis force-sensing cantilever capable of micro-Newton resolution. We observed that gecko-like properties were observed for tapered pillars but not for pillars of uniform cross-section.
Most synthetic adhesive architectures use a uniform cross-section beam but these results suggest such a design does not capture gecko-like behavior. These results point to ways to optimize the type of adhesion demonstrated by the synthetic dry adhesives and to create adhesives tailored for the application.
Borrowing themes from the gecko, we developed a synthetic adhesive possessing similar properties using molded arrays of micron-scale silicone pillars. These arrays demonstrate the gecko property of frictional adhesion where increased shear stress at the interface leads to increased normal load capacity. To distinguish between intrinsic and emergent behavior, we also isolated single pillars to test on a dual-axis force-sensing cantilever capable of micro-Newton resolution. We observed that gecko-like properties were observed for tapered pillars but not for pillars of uniform cross-section.
Most synthetic adhesive architectures use a uniform cross-section beam but these results suggest such a design does not capture gecko-like behavior. These results point to ways to optimize the type of adhesion demonstrated by the synthetic dry adhesives and to create adhesives tailored for the application.
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