to mimic the metallic sheen in beetles
Torben A. Lenau, Martin Aggerbeck, Steffen Nielsen
Technical University of Denmark, DTU Management Building 424, DK2800 Lyngby,
SPIE Optics & Photonics
- The Biomimetics and Bioinspiration conference, 2-6 August 2009, San
A range of different beetles exhibits brilliant colours and metallic sheen.
One of the most spectacular species is the Plusiotis resplendens from
Central America with gold metal appearance. The beetle shells are made
from chitin and have a number of unique properties that apart from spectacular
aesthetic effects include metal sheen from non-metal surfaces combined
with electric and thermal insulation. The reflection mechanism has been
studied by a number of authors and is well understood. Basically there
are 2 different reflection principles. One is the multilayer reflector
where alternating layers have high and low refractive index. The other
is the Bouligand structure where birefringent chiral nanofibres are organised
in spiral structures. The paper describes work done to explore different
approaches to mimic these structures using polymer based materials and
production methods that are suitable for more complex double curved geometry.
One approach is to use alternating layers of 2 different polymers applied
by dipping and another is applying cholesteric liquid crystals in paint.
However, none of them can yet make the desired metal-looking free-form
Keywords: Biomimetics, aesthetics, beetles, structural colour,
thin layer interference, bouligand structure, cholesteric liquid crystals.