TY - JOUR
T1 - Frictional adhesion of patterned surfaces and implications for gecko and biomimetic systems
AU - Zeng, Hongbo
AU - Pesika, Noshir
AU - Tian, Yu
AU - Zhao, Boxin
AU - Chen, Yunfei
AU - Tirrell, Matthew
AU - Turner, Kimberly L.
AU - Israelachvili, Jacob N.
PY - 2009/7/7
Y1 - 2009/7/7
N2 - Geckos and smaller animals such as flies, beetles, and spiders have extraordinary climbing abilities: They can firmly attach and rapidly detach from almost any kind of surface. In the case of geckos, this ability is attributed to the surface topography of their attachment pads, which are covered with fine columnar structures (setae). Inspired by this biological system, various kinds of regularly structured or "patterned" surfaces are being fabricated for use as responsive adhesives or in robotic systems. In this study, we theoretically analyze the correlated adhesion and friction (frictional adhesion) of patterned surfaces against smooth (unstructured) surfaces by applying well-established theories of van der Waals forces, together with the classic Johnson-Kendall-Roberts (JKR) theory of contact (or adhesion) mechanics, to recent theories of adhesion-controlled friction. Our results, when considered with recent experiments, suggest criteria for simultaneously optimizing the adhesion and friction of patterned surfaces. We show that both the van der Waals adhesion and the friction forces of flexible, tilted, and optimally spaced setal stalks or (synthetic) pillars are high enough to support not only a large gecko on rough surfaces of ceilings (adhesion) and walls (friction) but also a human being if the foot or toe pads-effectively the area of the hands-have a total area estimated at ∼230 cm 2.
AB - Geckos and smaller animals such as flies, beetles, and spiders have extraordinary climbing abilities: They can firmly attach and rapidly detach from almost any kind of surface. In the case of geckos, this ability is attributed to the surface topography of their attachment pads, which are covered with fine columnar structures (setae). Inspired by this biological system, various kinds of regularly structured or "patterned" surfaces are being fabricated for use as responsive adhesives or in robotic systems. In this study, we theoretically analyze the correlated adhesion and friction (frictional adhesion) of patterned surfaces against smooth (unstructured) surfaces by applying well-established theories of van der Waals forces, together with the classic Johnson-Kendall-Roberts (JKR) theory of contact (or adhesion) mechanics, to recent theories of adhesion-controlled friction. Our results, when considered with recent experiments, suggest criteria for simultaneously optimizing the adhesion and friction of patterned surfaces. We show that both the van der Waals adhesion and the friction forces of flexible, tilted, and optimally spaced setal stalks or (synthetic) pillars are high enough to support not only a large gecko on rough surfaces of ceilings (adhesion) and walls (friction) but also a human being if the foot or toe pads-effectively the area of the hands-have a total area estimated at ∼230 cm 2.
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U2 - 10.1021/la900877h
DO - 10.1021/la900877h
M3 - Article
C2 - 19522483
AN - SCOPUS:67650067872
SN - 0743-7463
VL - 25
SP - 7486
EP - 7495
JO - Langmuir
JF - Langmuir
IS - 13
ER -