Photonic Structures in the Animal Kingdom: Valuable Inspirations for Biomimetic Applications - Biomimetic Architectures by Plasma Processing - page 2

exploited photonic structures since the Cambrian explosion over
500 million years ago, which started an enormous diversification
of life. Ever since, the (co-)evolution of prey and predators has led
to the amazing diversity of biological organisms present nowadays
that make use of different colouration mechanisms to reflect bright
colours [2,3].
The most dazzling colours of animals are structural colours
that are generated by the interaction of light with (quasi-)ordered
nanostructured materials, with an order on the mesoscale,

200 nm
[1-5]. These nanostructured materials reside in the outermost parts
of the animal integuments, for example, the feathers of birds, the
elytra and scales of beetles and the wing scales of butterflies, so to
allow an effective interaction with incoming light.
Structural colours are often iridescent, that is, the colour of
the animal's body surface changes with the viewing angle. As a
consequence of the highly changeable colours, iridescent colours are
often described as rainbow-like, metallic, sparkling or opalescent.
The striking examples of natural iridescent colours can also be
encountered in a whole range of biological organisms other than
birds, beetles and butterflies. Various bacteria, plants and fruits
feature strongly iridescent colours, which are also seen in non-living
materials, such as in minerals, as opals and shells [6,7]. Every day,
we encounter structural colours not only in the splendid colours
of soap bubbles, but also in CD's and the metallic coatings of many
electronic devices (e.g. mobile phones).
From a physical point-of-view, the astonishing palette of
organismal photonic nanostructures harbours very effective light
control devices and, since also many man-made photonic materials
from the 20th and 21st century rely on proper knowledge of light
manipulation and control, these biological structures offer an
important source for inspiration of technological applications, which
has given rise to the field of biomimicry or biomimetics [4,8-10].
A precise interpretation of the biological photonic structures often
leads to the development of new high-tech materials, especially
since biological materials often surpass materials generated by
present day manufacturing in terms of quality and optical effects.
Biological photonic structures are, for this reason, often used as the
blueprints for a reproduction of these structures by technological
processes (see [4] and Section 1.4).

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