Page 22 - Biomimetics: Technology Imitates Nature

Biomimetics: Technology Imitates Nature

ties, possess lightness and the ability to withstand high
temperatures required by such vehicles as rockets, space
shuttles, and research satellites when leaving and entering
the Earth’s atmosphere. Work on the giant supersonic pas-
senger carriers planned for intercontinental travel also re-
quires light, heat-resistant materials. In medicine, the pro-
‹lhan Aksay duction of artificial bone requires materials that combine
spongy appearance with hard structure, and tissue as close

as possible to that found in nature. 17
To produce ceramic, used for a wide range of purposes from con-
o
struction to electrical equipment, temperatures greater than 1,000-1,500 C
o
(1,830-2,730 F) are generally needed.
Several ceramic materials exist in nature, yet such high temperatures
are never used to create them. A mussel, for instance, secretes its shell in
o
o
a perfect manner at only 4 C (39 F). This example of nature’s superior cre-
ation drew the attention of Turkish scientist Ilhan Aksay, who turned his
thoughts to wondering how we might produce better, stronger, useful
and functional ceramics.
Examining the internal structures of the shells of a number of sea
creatures, Aksay noticed the extraordinary properties of abalone shells.
Magnified 300,000 times with an electron microscope, the shell resembled
a brick wall, with calcium carbonate “bricks” al-
ternating with a protein “mortar.” Despite
calcium carbonate’s essentially brit-
tle nature, the shell was extremely
strong due to its laminated struc-
ture and less brittle than man-made
ceramics. Aksay found that its lami-
nation helps keep cracks from
propagating, in roughly the

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