Natures template

Andrew Parker unveils the stunning realm of optical biomimetics

Occasionally Nature inspires completely new biomimetic inventions: from George de Mestral’s 1941 discovery of Velcro, when he noted how burdock seeds stuck to his clothing, to today’s superglues based on the Van der Waals’ forces in the forests of tiny hair-like setae on a gecko’s foot. More often, natural structures provide flawless examples of concepts already half-explored: the self-cleaning surface of the lotus leaf; the drag-reducing aerodynamics of a shark’s skin.  

Dazzling optical effects, in particular, are often due to nanostructures understood by physicists but not noted in Nature until the last few decades. Anti-reflective surfaces on moths’ eyes that help them see in low-light conditions; iridescent scales on butterfly wings (right) and other insect scales that attract, camouflage, or startle - all are examples of nature’s own metamaterials.  

It’s no longer surprising - though always a pleasure - to see that millions of years of evolution has anticipated the latest physics and chemistry. And nanoscientists have happily plundered these spoils by mimicking natural structures to manufacture impressive and useful devices. 

But in the nano-sized realm, copying sometimes isn’t good enough. Lithography can’t always accurately mimic Nature’s elaborate architecture, or if it can, commercial-scale manufacture is too expensive. Scientists are now realising that Nature needn’t just inspire new designs: cells can actually be hijacked to grow natural structures for us.  

To begin with, we have borrowed Nature’s ready-made templates. Viruses have been harvested as building blocks to create iridescent films, while diatoms - single-celled algae - have been chemically converted into lace-like structures of nanocomposite materials. 

But we still don’t understand how cells grow their finely-branched designs in the first place. Intriguingly, the same kinds of nanostructures are found in many unrelated species - suggesting that all cells may use similar moulds, scaffolds, or templates. The ultimate goal of biomimetics may be to copy not Nature’s designs, but its biomachinery - supplying the recipe to help optical nanostructures grow themselves. 

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