Biomimicking strength

‘Nobody ever figures out what life is all about, and it doesn't matter. Explore the world. Nearly everything is really interesting if you go into it deeply enough’. Richard P. Feynman.

Bio-mimicry refers to the method of synthetically replicating nature’s processes and applying them to human-made design challenges. The term has also been described as the process of not only learning about nature but learning from nature.

[1] Exploration Architecture (2021) (A) has produced a 3D-printed structure modelled on a cross-section of a bird's skull  as an example of a very complex light weight and efficient structure. Michael Pawlyn (B) bird skull janusjansen 3D artist.(C) (D) The Biorock Pavilion could be grown underwater, The form of the building is based on that of a seashell, as well as mathematical forms.

[2] It would be grown by electrodeposition of minerals - Exploration Architecture (2021)

An electric current would then be run through the steel skeleton, allowing the remainder of the pavilion to be 'grown' as the minerals calcify atop the base structure.

"It takes those minerals out of the seawater and produces a structure similar to reinforced concrete," stated Pawlyn. "This uses an absolute minimum of material to grow a whole building."

The concept of Bio-mimicry is neither new nor unfamiliar. It has been used as both a tool and a source of inspiration for engineers and designers for many years. Indeed, far from being new, it leverages the hidden technologies that nature has perfected through infinite iterations of evolutionary trial and error over the past 3.8 billion years. On that basis, Bio-mimicry seeks to unlock the awesome design potential that nature offers - nature being the ultimate designer. Nature’s design principles are characterised by the perfect arrangement of each element in the design; it follows that material technology should aspire to follow the same principles through the assembly of the best components in an optimal way.

[3] Architect Melissa Shin explores the vicissitudinous juxtaposition between contemporary art and the environment in which it is exhibited. The project was influenced by various sea creatures (Dumbo Octopus, Flamboyant Cuttlefish, etc).

Other sources of inspiration included Sol LeWitt; Musée Océanographique in Monaco; Expo ’70 in Osaka, Japan; Ernesto Neto and the surrealist photography of Hans Bellmer.

Nature excels in the production of materials. It combines simple components like chitin, keratin, calcium carbonate and silica to create structures of fantastic complexity, strength and toughness. However, the artificial replication of such technologies in relation to man-made problems is neither easy nor always sustainable. For instance, spiders’ silk is one of the strongest materials found in nature. To produce a strong fibre, spiders make their silk with an array of spinnerets which conjoin to produce an aligned stream of polymers. These are then ‘spun’ into a silk thread with the spider’s back legs which, when dry, is stronger than Kevlar.

Kevlar, also termed ‘aramid fibre’, was (prior to graphene) the strongest synthetic fibre that we have been able to manufacture to date. The complexity of its production process illustrates the inherent difficulties in reproducing materials with attributes which mimic nature’s own. The traditional manufacturing process for producing aramid fibre requires petroleum to be boiled in sulphuric acid at around 750 °C. The mixture is then subjected to high pressure to get the molecules into place, producing large quantities of toxic waste. Nevertheless, spiders manage to do the same at ambient temperatures, with digested flies and water as their only source of raw material.

Mueller, T. (2008). Biomimetics, National Geographic, April 2008.

Scientists have recently developed more sustainable ways to produce synthetic spider silk molecules by manipulating E-coli bacteria and yeast fermentation processes. However, scaling-up these processes in a commercially viable way for a mass market has generally failed and has tended to raise environmental impact concerns. How, one might ask, can nature guide us in bridging the gap between such contrasting manufacturing methods? How can we transform material technologies to better embody the principles of material production in nature whilst making them commercially viable and truly sustainable for the planet?

[4] Limpet (Patella vulgata)

The limpet, for example, makes its teeth out of the naturally occurring materials chitin and goethite. It moulds and crystallises this material into walls of staggered nano-scale bricks through a subtle inter-play of proteins. In so doing, it creates ‘teeth’ which are tougher than spiders’ silk or man-made materials such as Kevlar.

[5] ICT scan of limpet radula - Michael Crutchley (2015)

To put the strength of this material into context, Professor Asa Barber of the University of Portsmouth compares it to a single spaghetti strand holding 3,000 half-kilogram bags of sugar (1.5 metric tons), with a tensile strength of 5GPa.

[6] Asa H. Barber, Dun Lu and Nicola M. Pugno - Published by the Royal Society (2015)

Scanning electron micrographs showing (a) the limpet tooth prior to FIB milling, (b) FIB sectioning and attachment of the limpet tooth cusp to an AFM probe and (c) further FIB milling to thin the sample towards a ‘dog-bone’ geometry - preparation for tensile strength test.

The potential benefits of this material extend beyond its tensile strength. The unique mechanical structures which can be observed in limpet tooth production also provide parametric data which can be intersected with digital technologies. This can be used to provide unique solutions in diverse areas - such as with automated construction technologies in architecture, AI or even in medical sciences.

Interlude. . .

Limpet’s Job Description

Bio: The limpet is a self-sufficient organism that works from home with no briefcase, no cool bike, no Frappuccino to hand.

Job role: The job assigned by nature for its survival is to manufacture tools for catching food; it is tasked with making such tools within its own body by sourcing local materials such as rock and endolithic algae.

Other responsibilities, depending on the species, require it to fertilise algae with its own output to complete a circular sustainable production process.

Equipment: A production line of nano teeth, operated by a quasi-conveyor-belt mechanism called a radula. This is a tongue-like organ that originates deep in the mouth cavity of the mollusc and which extends out of the mouth by 2-5 mm. The radula mineralises teeth through a continuous cycle, producing new teeth as the old ones wear out. The result - a biodegradable high strength biomaterial.

Role risks: Hungry, noisy seagulls looking for lunch, hungry humans with a taste for shellfish, annoying children playing with limpets’ shells with no intention of consuming them as food and a work uniform (shell) which can crumble due to acidification of the water in its environment.

Do not be fooled by the ‘cuteness’ of the limpet. This mollusc is the quintessential model of sustainability and toughness. It is territorial and is keen to pick fights with other limpets. Nevertheless, in situations of danger (such as finding themselves inside a saucepan), they stick together to form a protective structure of shells.

[7] Kitchen-bio Lab - Photograph by Maël Henaff

The Bio-mimicking strength project was born out of a desire to explore how to translate nature's hidden technologies into practical design technologies - specifically with regard to high strength, naturally occurring materials.

The production of a sample test was originally intended to be performed by the laboratories at Imperial College London. However, due to the restrictions imposed by the COVID-19 lockdown, I have adapted the original protocol of the experiment by seeking to replicate the limpet's material production methods using only components available in my home environment (specifically at room temperature in my kitchen).

Due to restrictions, I adopted the Indian concept of Jugaad for the development of my project. Jugaad is a colloquial Hindi word which refers to a non-conventional, frugal innovation, often termed a "hack". It can also refer to an innovative fix or a simple work-around, a solution that bends the rules, or a resource that can be used in such a way.

It is also often used to signify creativity: to make existing things work or to create new things with meagre resources.

I therefore transformed my kitchen into a bio lab and adapted conventional product packaging (such as the plastic lids of milk cartons) and kitchenware (such as teapots) to substitute for 3D printed parts. These parts were initially intended to build a bioreactor for the 3D mineralisation of a chitosan gel, a process that mimics the limpet's teeth biomineralisation.

The experiment involved delivering positive and negative ions through a chitosan hydrogel by use of an electrical current, applying the method of electro-deposition of minerals.

It was critical to:

a. Re-create the material synthetically, since working with living organisms in the kitchen can be volatile and unpredictable.

b. Use non-conductive materials.

Naturally, this represents a critical shift in the paradigm being applied versus the original intended design approach. Instead of the design being used to create unique parts to serve a single specific function, I instead embraced the simplest of solutions by repurposing technologies that are already available around us (single-use materials found mostly in the bin).

Conclusion:

In exploring both the chemical composition and nano-scale structures that give this material its exceptional properties, the project has highlighted the immense power of design in nature. I hope I have also shown the potential for nature to act as an active collaborator so future materials and systems can evolve in more environmentally friendly ways.

Images
[1] [2] Exploration Architecture (2021) Michael Pawlyn Available at:

https://www.dezeen.com/2020/10/22/michael-pawlyn-exploration-architecture-dassault-systemes-video/

(B) bird skull janusjansen 3D artist. Available at:

https://sketchfab.com/3d-models/aptenodytes-adult-7a4598419bb444749d5e46883640d3fd

[3] Architect Melissa Shin - Interview with Sucker punch daily Available at:

http://www.suckerpunchdaily.com/2012/02/07/bny-contemporary/

[4] Limpet (Patella vulgata) Available at: https://en.wikipedia.org/wiki/Patella_vulgata

[5] ICT scan of limpet radula - Michael Crutchley (2015) Available at: https://www.nikonsmallworld.com/galleries/2015-photomicrography-competition/radula-feeding-structure-of-an-aquatic-snail-limpet

[6] Asa H. Barber, Dun Lu and Nicola M. Pugno - Published by the Royal Society (2015) Available at: https://doi.org/10.1098/rsif.2014.1326

[7] Carolina Perez Leon (2020) Kitchen-bio Lab - Photograph by Maël Henaff

Written by Carolina Perez Leon