Dr Michelle Oyen explores natural building blocks and asks can we rethink how we build our future cities?
Dr Oyen will be giving a talk on Wednesday 9 March, Biomimetic materials: rethinking how we build stuff.
CSF: What are biomimetic materials?
MO: Biomimetic materials are materials that are (literally) copying nature, or (more generally) inspired by nature. This concept can be generalisable to other biomimetic structures or systems as well, across broader fields than just materials engineering. For example, there has been a lot of recent interest in making robots that crawl like insects, fly like birds with flapping wings, or swim like tuna fish. And of course, no one seems to be able to resist the idea of becoming a human Spiderman and crawling up the sides of buildings the way some insects and geckos can, even if it’s been shown that we’re simply too big and too heavy for that to be practical!
CSF: How does biomimetics relate to architectural engineering? For instance, what levels of nature do bioengineers look to, eg organism, behaviour, etc?
MO: Engineers have taken inspiration from nature at different levels, including in material, structure, and device forms. Materials are particularly interesting because nature figured out millions of years ago that it was desirable to make materials that were composites—made from multiple different materials, often with very different properties in order to exploit the unique behaviours that result from disparate combinations. As engineers, we have historically tended to make monolithic materials, although we’ve increasingly looked towards composites since the 1950s. Of course, when strength and lightness are desired, as in modern commercial aircraft, composite materials are the only practical choice. Aside from their composite nature, other interesting features of natural materials that differ from monolithic engineering materials include local compositional heterogeneity and functional gradients. Some features of natural materials are already being exploited in surprising ways, such as surfaces for hospitals that are based on shark skin but naturally anti-bacterial and self-cleaning paints modelled after lotus leaves.
CSF: How can it solve problems in the contemporary, man-made environment?
MO: The single biggest problem with modern materials, and building with modern materials as a direct extension, is their energy footprint. If one considers all the contributors to carbon dioxide emissions and the global carbon footprint, steel and concrete are both ubiquitous and amongst the greatest negative contributors. In addition to the energy input at the time of fabrication, many engineering materials are not recyclable, or not recyclable in a very cost-effective manner. So an appropriately named ‘life-cycle analysis’ of a natural or nature-inspired material is going to demonstrate advantages across both initial manufacturing and end of service timepoints compared with engineering materials.
CSF: What are some of the challenges with bioengineered materials and systems?
MO: One reason that it’s challenging for engineers to directly mimic natural materials in a most literal sense is that fundamental paradigm that life comes from life. Natural materials are manufactured by or under the influence of living creatures, from the level of biological cells up to complex organisms like ourselves. Most natural materials have a protein component, and proteins are the direct translation of DNA. So until we really crack the code of how life began, we are stuck being more inspired by nature than by making literal copies.
CSF: Are there any current examples?
MO: The Eden Project in Cornwall is an oft-cited example of taking ideas from nature, and one of the associated architects (Michael Pawlyn) has been a great proponent of biomimicry. The architect Gaudi is often credited with being an early adopter of bio-inspired architecture. At the material level, several different groups have tried to make materials modelled after nacre, the material associated with seashells.
CSF: Which is the most outlandish example?
MO: I quite like the idea of an office building modelled after a termite mound. There have been several claims to such a structure in the popular literature, but thus far the idea seems to be more of a flight of fancy than a real world entity. However, one can easily see why the idea is popular, since the mounds can be extremely large relative to the size of the occupants who built them, the natural materials from which they’re made include a critical component of termite spit, and their natural air handling system provides electricity-free air conditioning.
CSF: What's the most exciting research happening right now?
MO: Most exciting from my perspective is the idea that engineers are starting to think about our impact on the world, and how we can use this inspiration from nature to re-think how we do things. At the moment I’d say the penetration of these ideas is relatively small in proportion to all of the technologies and industries impacted by engineering. Architecture is in some ways thus leading the field, and it will be interesting to see how other aspects of engineering and technology follow.
CSF: And what can we hope to see in the next decade?
MO: More discussion within engineering of being kinder to the planet instead of just making life more convenient with technology. More discussion about recyclability of materials and components, especially those that are either long-lived or toxic when placed into landfills. More use of existing natural materials, like timber and mud bricks, polysaccharide (sugar)-based plastics instead of those made from petrochemicals. And finally, truly biomimetic materials, such as artificial seashell or bone.