Color Change in Chameleons

“The genius of the Man makes several inventions, including with various instruments one and the same end, but never discover an invention more beautiful, more economical or more direct than from nature, because it lacks nothing and nothing is superfluous.”

Leonardo da Vinci1

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    1. Objective

This essay “Buildings with chameleon behavior” aims to identify and understand some of the characteristics of physical chameleon´s camouflage and how they can be used in the conceptualizing of new forms of coatings for the buildings facades.

In chapter 2, we analyze aspects related to the biological properties of the chameleon skin which allow them to change color;

In chapter 3, some conceptual ideas applied to buildings will be expressed based on the phenomenon of structural changes as well as colour change in the chameleon’s skin;

In chapter 4, some examples of materials and applications will be explained there are some research of materials with color change capabilities and applications;


   3. Analysing chameleon colour change

Nature spontaneously build forms and shapes, structures, functions and behaviors, for all the live beings, which carefully analyzed can be a source of understanding of new ways for solving our own architectural challenges and problems. Under this assumption is intended with this work to investigate the chameleon’s characteristics, to see how they can be useful in this context.

Although, taking into account the various capabilities presented in the chameleon, like their abilities of 360 degrees’ ultraviolet vision, different sizes, way of locomotion, and feeding, this essay will be focused mainly on their ability to change color. To understand the phenomenon of colour change we must take into account the biology of this animal. The chameleon has cells organized in layers, called chromophores, which allow the existence of coloured tones. Basically the changing tones are due to dispersion/aggregation of pigment containing organelles within dermal chromophores. In detail we know that the chameleon has four elastic layers of cells each having different pigment grains, as shown in Figure 1. The concentration is regulated by hormones transported into the bloodstream.

2Figure 1 – Como o Camaleão muda de cor – Nova Escola

The two most important layers are the upper ones, which are responsible for rapid structural color changes through active tuning of guanine (one of the DNA components) nanocrystal spacing in a triangular lattice. The deeper population of cells broadly reflects light, especially in the near-infrared range. This arrangement of high and low refractive index materials (nguanine = 1.83; ncytoplasm = 1:33) has the potential of behaving as a so-called photonic crystal, similar to those that generate bright colors in some birds and insects.

3Figure 2. – Source: Photonic crystals cause active colour change in chameleons

In a simple way when the autonomic nervous system of the chameleon is submitted to stimulations, such as, light or temperature changes producing different emotions, the layers will expand and pigments will spread manifesting different colours (fig3.rigth). With the layer’s contraction, the grains will group again resulting in the restoration of the original colour (fig.3.left). The final appearance comes from the combination of the tones of the layers.4

Figure 3. – Source: Photonic crystals cause active colour change in chameleons

The speed with which a chameleon changes his color varies, can take, under the right conditions, only a few seconds, but sometimes, as with a slow temperature change, the color change also occurs more slowly.  For example, when the sun is rising after a cold night, the chromatophores (a cell or plastid that contains pigment) of a normally light brown chameleon expand, making their skin take a dense dark chocolate color, which helps absorb light and heat into his body. On the other hand, if the reptile becomes very hot after “cooking” in the afternoon sun, the dark chromatophores contract, reducing brown pigmentation and allowing a lighter skin that can reflect the sun’s rays.


   3. Conceptual idea of colour changes in building structures

The idea based of the ability that chameleon have to change its colour when exposed to different temperatures can be applied to the universe and language of architecture, allowing to think other solutions for controlling the temperature inside structures and buildings.

This way we can think of some kind of dynamic colour changes in buildings from lighter colours to warmer colours when the temperature rises and vice-versa. We can also imagine building coating having different colours, taking into account different solar incidences, analogously to the colour changes in the skin of the chameleon.

Not least important than the chromatic transposition is the phenomenon of the expansion and retraction of the chameleon cells. For this purpose, we could think of some kind of coating or structure materials capable of preforming retraction or expansion as temperature changes, upon the need for ventilation. Also, this behavior could be very useful in terms of regulating natural light intensity into the interior of buildings, that is, allowing more or less light through the expansion or transparent areas in accordance with a lower or higher solar incidence.

The binomial temperature / solar incidence could lead to a “live building structure” capable of exhibit different colours with different exposure and solar orientation, as well as different ambient temperatures. Alongside with the effect described above it could also be of interest to have changes in coating translucency or transparency (by means of expansion / retraction of cell structure) for different areas of the building as the level of sun exposure varies.

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  1. A colored structure in mobile panels, moving by sunlight and temperature.
  2. A set of panels that rotate depending on the temperature.
  3. One type of material which expands and shrinks depending on the sunlight.
  4. A structure that opens and closes by means of the temperature, showing a chromatic composition in the interior.

4. Existing materials capable of changing colour and applications

  •  Tiles that change color

The Thermeleon is a tile which aims to save energy in homes. This tile is able to change color to best take advantage of the heat and save energy. Thus, the tiles are black or white depending on the ambient temperature.5

Figure 4 – Telha que muda de cor (Tile With Changing Color Capacity) – Wikienergia

  • Chameleon Building (Wanders Werner Falasi Arquitects)

The hexagonal forms that predominate in this project are derived from the cell structures of the chameleon characteristics, including color change. For this, the studio opted to include
LED lighting and integrated thermoregulation.6

Figure 5 – Wanders Werner Falasi Architects

This temperature control is accomplished through intelligent façade units that mechanically adapt the path of the sun. Thus when the building receives excessive radiation, each component is sealingly closed structure. Similarly when temperatures are low or poor lighting is they open.

  • Ebb Tecnology

The Ebb technology, still in development, seeks to create new types of smart clothing that change the color, patternand logo by the taste of the person using them.

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Figure 6 – TecoQuest

  • Chameleon Syntetic Skin

US scientists have created an ultra-thin film that can change colors as easily as the skin of a chameleon when pulled or twisted.

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Figure 7 – The Optical Society (OSA)

  • A metal mesh that reacts to heat

This shading system is made with a thermobimetalequipment – a laminate of two different metals, each with its own coefficient of thermal expansion. This means that each side reacts differently to sunlight. Then, when the surface is hot , thin panels in the shade to curl up to allow more air to move to the space below and when it cools down, it closes again.

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Figure 8 – USC architecture

  • Kolding Campus of the University

The central building Kolding Campus of the University of Southern Denmark is one of the first in the country with responsive facades, equipped with an innovative dynamic shading system that adjusts itself according to the angle of incidence and intensity of sunlight.11

Figure 9 – Kolding Campus 

  • Adaptive Fa[CA]de

Adaptive Fa[CA]de is an exploration of Marilena Skavara, which explores a new field of possibilities and cellular automata behaviors to be applied in architecture.12

Figure 10 –Adaptive Fa[CA]de

The panels which are able to alter their states to 7 different inclinations to adapt to the different changes of light that can be generated. The goal: an immediate response to every light change to occur, with the idea of optimum condition.


   Bibliography 

      Books

SANTOS Claudemilson – O DESENHO COMO PROCESSO DE APLICAÇÃO DA BIOMIMÉTICA NA ARQUITETURA E NO DESIGN, Professor do Departamento d Planejamento, Urbanismo e Ambiente da Universidade Estadual Paulista

TEYSSIER Jérémie; SAENKO Suzanne , MAREL Dirk van der  & MILINKOVITCH  – Photonic crystals cause active colour change in chameleons Article

F.B. Detanicoa,b , F.G. Teixeirab , T.K. Silvab  – A Biomimética como Método Criativo para o Projeto de Produto. – 2010

Online

http://www.bbc.com/news/science-environment-31819588

http://www.pgdesign.ufrgs.br/designetecnologia/index.php/det/article/viewFile/52/33

http://hypescience.com/como-os-camaleoes-mudam-de-cor/

http://www.livescience.com/50096-chameleons-color-change.html

http://www.suapesquisa.com/mundoanimal/camaleao.htm

 

 

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