From: Amara Graps (amara@amara.com)
Date: Thu Jun 19 2003 - 19:31:52 MDT
following up on a topic from last August 2002
The Economist 7 June 2003
Sticky tape
Echoes of geckos
A new adhesive tape works like a lizard's foot
Engineers frequently admire the ways in which living creatures solve
problems. However they rarely manage to emulate them. But Andrey Geim
from Manchester University, in England, and his colleagues have done
so. In a paper just published in Nature Materials, they describe how
they replicated the way that geckos cling to ceilings in a new
glue-free adhesive tape.
A gecko's powers come from tiny hairs on the soles of its feet. Each
hair sticks to any surface it touches by a combination of capillary
action due to water it has absorbed and so-called van der Waals
forces - electrostatic interactions between individual molecules.
Though the attraction between a hair and a surface is tiny, geckos
have zillions of such hairs, and the sum of the interactions is
enough to hold a lizard to the ceiling.
Dr. Geim and his colleagues used electron-beam lithography (a
technique employed in the manufacture of computer chips) to
fabricate small pieces of plastic tape that had hairlike
protuberances on their surfaces. They created a range of surfaces
with hairs measuring between a fifth of a micron (millionth of a
metre) and four microns in diameter, and with around 100m hairs per
square centimetre. Dr. Geim reckons that a person wearing gloves
made from the tape could stick to a wall as well as a gecko does. He
has not yet done that experiment, though, for the pieces of tape
that the team has produced so far are only a square centimetre in
area.
There is still some way to go before gecko tape becomes a commercial
reality. The prototype is delicate stuff, losing its adhesive powers
after three or four uses. And electron-beam lithography does not
lend itself to mass production. But if it could be made cheaply,
geckotape would have many uses. Move over Spiderman, Geckoman is on
his way.
Previous extro Gecko conversations:
http://forum.javien.com/XMLmessage.php?id=id::MR1jZwl2-fhsH-cCkY-DU8P-KjA@THwELhpy
http://forum.javien.com/XMLmessage.php?id=id::AjUiNzhC-WG54-AEt_-YXMo-CFVMBEE1JB4x
-- ******************************************************************** Amara Graps, PhD email: amara@amara.com Computational Physics vita: ftp://ftp.amara.com/pub/resume.txt Multiplex Answers URL: http://www.amara.com/ ******************************************************************** "It seems like once people grow up, they have no idea what's cool." --Calvin
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