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10-Jan-2005

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Twinkle Toes: How Geckos' Sticky Feet Stay Clean, Science News
 









Excerpts:     Toe Print. When the underside of a gecko toe (left) was dusted
with microspheres and pressed onto glass, millions of sticky fibers in the thin,
platelike structures shed microspheres onto the glass, leaving a print visible
under laser light (right). Autumn   

To find out how gecko feet clean themselves, the team considered the van der
Waals forces that a surface, such as a wall, exerts on a microsphere. They then
compared that attraction with the hold on the particle by toe fibers. Using
simplified geometric models that represent the ends of the fibers as shallow
cups or flexible strips, the scientists calculated that from 26 to 59 of the
fibers would have to cling to each microsphere to keep it from sticking to the
wall as the gecko steps away.

 Yet in most cases, "when you look under an electron microscope, you don't
observe that many [fibers] actually attached to a single dirt particle," Autumn
notes. Hence, when the fibers and the surface compete for a dirt particle, the
surface usually wins.
Source: Twinkle Toes: How Geckos' Sticky Feet Stay Clean[
http://www.sciencenews.org/articles/20050108/fob6.asp ], Peter Weiss,
ScienceNews, 05/01/08
AUDIO - Audible Format[ http://www.audible.com/sciencenews/ ]

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