Lecture: Biomimicry

Tony and I attended a talk at the Two Oceans Aquarium in June, given by two staff members of Biomimicry South Africa. We’re crazy like that.

Biomimicry is the practice of learning from nature, and then attempting to emulate nature’s solutions in solving problems that humans face. The biomimic can imitate (in increasing order of sophistication) form or shape, a natural process, or an entire ecosystem.

The talk made me feel as though I was attending my first meeting at a cult – the woman who “founded” the modern biomimicry movement, Janine Benyus, was repeatedly and reverently referred to as “our teacher”, and there is clearly a shared vocabulary and phraseology that goes beyond mere scientific convenience. Excessive devotion aside, the talk was mostly concerned with explaining biomimicry by means of examples, some of which are very exciting. My favourite examples are those inspired by water and the creatures that live in it.

Humpback whales

When feeding, humpback whales use a technique called bubble curtains to concentrate their food in a small area. To achieve this, they somehow manage to turn their double-decker bus sized bodies in ever decreasing circles. They are able to do this because of the tubercules – knobbly bumps – on the leading edges of their very long pectoral fins. The tubercules influence the water flow over the fin, allowing their fins to function at a steeper angle than a straight-edged fin would. They provided increased lift and decrease the amount of drag experienced by the whale.

WInd farm off the coast of Denmark

Wind turbine blades manufactured with tubercules on their leading edges are able to operate in both higher and lower speed winds than conventional turbines. Industrial fan blades and aircraft wings have also been constructed using this insight.

Boxfish

You wouldn’t say so, but the humble boxfish is a miracle of streamlining. Taking the shape of the boxfish’s body as a template, engineers at Daimler (well, Mercedes Benz) designed an incredibly fuel-efficient concept car that happens also to be quite cute to look at. Furthermore, the hexagonal bony plates that hold the boxfish in a stable shape were also transferred to the car’s design, resulting in a weight reduction without loss of safety and strength.

Boxy, yes? (This isn't the concept car, it's the A180)

Shark skin (I)

Speedo’s Fastskin LZR racing swimsuits first came to the attention of the general public at the 2008 Beijing Olympics, where a large number of the swimming records were toppled by athletes wearing these suits. Inspired by sharks’ skin, which is covered in enamel-plated denticles that actively push water away from the surface of the skin, these suits use different kinds of fabric over different parts of the body, just as a shark’s skin varies over its body.

Airbus is working on incorporating shark skin-inspired coatings with their airplane fuselages, to reduce fuel consumption.

Shark skin (II)

Sharks are the only slow-moving ocean creatures that don’t foul (i.e. get barnacles, algae and other small passengers adhering to them). Not only does shark skin have impressive streamlining qualities, but the configuration of the ridges on the denticles is such that bacteria and algae are discouraged from settling and breeding. Imitating the roughness qualities of sharks’ skin led to a coating that is used on high-touch surfaces such as in hospitals, restaurants and restrooms, thus reducing bacteria build-up by as much as 80%. The coating can also be used on boats. All of this reduces the need for toxic chemicals to remove bacteria and other fouling organisms, which is kinder to the environment, too. Sharklet Technologies is one of the companies working on this.

Aquaporins

Aquaporins are proteins embedded in cell membranes that regulate water flow. Aquaporins allow only water molecules to pass through, resulting in totally pure water. Instead of requiring high pressure and energy to treat water (desalination, for example), aquaporins use the properties of the water molecules to restrict the types of molecules they permit to pass through. This technology has medical applications, for example in conditions that result in fluid build up in parts of the body, and can reduce the energy required to desalinate water by up to 70%.

Lotus leaves

Lotus leaves exhibit superhydrophobicity – they’re very afraid of water. Water does not dissipate on their surface, owing to the microtopography (essentially the texture) of the leaves. Airbus, a leader in biomimetic design, has been incorporating material based on lotus leaves on their airline seats, carpets, and on bathroom surfaces. This makes the surfaces easier to clean and more hygienic.

Also working with this principle, Stocorp makes building exterior coatings that repel rain and are easy to clean.

Kelp plants

BioPower Systems develop devices to extract clean energy from ocean waves and tidal currents. These devices are anchored to the ocean floor using a mechanism inspired by the holdfasts of kelp plants.

Water vortices

If you’ve ever run and then emptied your own bath – and I assume, unless Queen Elizabeth II is reading this blog, that you have – you’ll be aware that water likes to travel in vortices. These are swirling pathways that are typically logarithmic spirals (i.e. the ratio between successive spirals is constant). Inspired by natural water flow and the golden ratio, the Pax Group “froze” a vortex shape and used it to create an impeller (to the untrained eye – me – it looks just like a PROpeller, except it apparently pulls rather than pushes water). The uses of this design are many, but the one I liked the most was to mix huge tanks of liquid. A self-reinforcing pattern of fluid flow is set up, and because of the golden ratio encapsulated in the impeller blades, all interference is constructive. A tiny handbag-sized impeller can do the same job as a propeller the size of a compact car. The design can also be used to replace fans of all shapes and sizes.

Water bears/tardigrades

Water bears look like polar bears, except with too many legs. They’re also called tardigrades and moss piglets, and apart from being cute (some think), they have incredible powers of survival, if you will. They can be frozen to near absolute zero (-273.15 degrees celcius), heated to 150 degrees celcius, dessicated so that only 3% of their water content remains and left in that state for over 10 years, be exposed to 1000 times the amount of radiation that a human can withstand, and survive the vacuum of space. You could do all those things to me… and I’d die – but if you do them to a waterbear, and then drop it into a glass of water when you’re done, it’ll simply reanimate and toddle away.

Imitating the ways in which waterbears do all these things enables us to create vaccines that don’t need to be refrigerated constantly (a huge issue in the third world)

Venus flower basket

The venus flower basket is a deep ocean sponge that manufactures its own magnificent glass-like silica structure from silicic acid that it extracts from sea water. It’s 1000 times stronger than glass and endures pressure of up to 300 times atmospheric pressure on the ocean floor. It exists at temperatures below 4 degrees celcius. Even the most basic knowledge of how the glass we use in our windows and other objects is made will convince you that the feats performed by this sponge are something quite special. The sponge is of interest in fibre optic research, because man-made fibre optics are brittle and require high temperatures to be forged.

Wired Magazine has a slideshow of some of these examples, plus a few more, that can be found here.