Through the course of billion years, nature has gone through a process of trial and error to refine the living organisms, processes and materials on planet Earth. The emerging field of Biomimetics has given rise to new technologies created from biologically inspired engineering in both the macro scale and nano-scale levels. Biomimetics may also offer solutions to environmental and social problems caused due to dyeing. Dyes have been recognized as carcinogenic and harm the flaura and fauna as well. Natural color mechanisms and structural study of such natural phenomenon may offer best alternate to dyes and therefore may revolutionize the dyeing and printing industry.
Animals, plants and insects in nature evolved over billions of years to develop more efficient solutions than comparable man-made solutions to date. Some of these solutions have inspired humans to achieve outstanding outcomes. Several examples can be quoted for this and self cleaning materials which are derived from emulating the lotus leaf effect, production of hollow fibers inspired from polar bears, etc are just a few of them.
Why do we need a substitute for dyes?
Dyes usually are of synthetic origins and have aromatic molecular structures. The dye effluents are highly coloured and their disposal into the environment can be extremely deleterious. Their presence in watercourses is aesthetically unacceptable and may be visible at concentration as low as 1 ppm. They also affect photosynthetic activity in acquatic systems by reducing light penetration. The low bio-degradability of dyes adds to another problem. The treatment methods for these effluents are quite expensive and have operational problems as well. Already some dyes have been banned as they have been identified allergic and carcinogenic. As the environmental regulations are becoming more stringent, the need for alternate methods of dyeing textiles has spurred up.
Bio-mimetics or imitation of nature means copying or adaptation or derivation from biology. It is derived from bios, meaning life (Greek) and mimesis, meaning to imitate. The term was first introduced in 1960 by Steele as, the science of systems which has some function copied from nature, or which represents characteristics of natural systems or their analogues.
Nature has unique abilities to manipulate light. Most surfaces in nature often produce brilliant, vivid and iridescent colours. If we look very carefully, wed find that colours actually alter with the change of angle of sunlight and eyesight. In the nature, colours consist of pigment colours and structural colours. Colours generated by pigment are based on the selective absorption of light, while structural colours are generated by selective reflection arising from dispersion, scattering, interference and diffraction.