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Rachel Armstrong

HOW PROTOCELLS

CAN MAKE ‘STUFF’ MUCH MORE INTERESTING

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Rachel Armstrong explains why living systems with their own metabolisms provide more exciting and far-reaching solutions than conventional building materials. She also explicitly explains why the pursuit of protocell technology, which enables us to artifi cially design living systems, is so much more promising than established methods, such as incorporating high-maintenance biological features – green walls or roofs – into existing urban context or applying biomimicry to traditional materials.

Philip Beesley, Hylozoic Ground installation, Canadian Pavilion, Venice Biennale, 2010The protocell populations are designed with the same metabolism. However, since they are sensitive to environmental conditions they respond locally to the presence of metal ions in the fl asks to produce a colourful landscape of crystals at the oil/water interface that gradually became petrifi ed over the duration of the exhibition.

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Imagine you have a spade full of ready-mix cement, which in the broadest sense is a binder, typically composed of calcium, silicon and aluminium salts, that combines constituent materials together. In front of you is a hole that you want the material to fi ll and provide structural support for a wooden post. You take your spade of concrete and throw it into the hole, packing it tightly around the base of the post. You add water. On activation, the mixture sets and hardens. It is a chemically dynamic process. You wait. The mixture takes the shape of the hole, it warms, it swells, it fi xes the post in the correct position, it produces carbon dioxide – lots of it – as part of its curing process, and it cools. Finally, the concrete sets, the chemical dynamism is lost and the post remains upright. The world turns. It rains, it snows, the ground dries in hot weather and gradually the edges of the hole recede and the concrete loosens from around the post. The material no longer serves its original purpose because the environment has changed and the once-malleable object is now obsolete. It is raining again and there is a lot of water around the base of the wobbly post. You somehow need to repeat the process or repair the existing system.

Concrete was a cutting-edge material in Roman times that enabled the binding together of discrete structures for the ambitious architectural projects that accompanied the expansion of the Roman Empire into the far reaches of Barbarian Europe. Nowadays industrial-scale manufacturing processes and machines replace manual labour and although a variety of facade materials, such as durable plastics, have been developed, the actual process of building has changed very little. However, concrete is the most widely used building material and is used in such quantities that this substance alone accounts for 5 per cent of our total carbon emissions. The current approach to the production of architecture is ancient and yet the technology that could potentially revolutionise our approach to the construction of buildings is even older than the invention of concrete. This technology is life.

Unlike the case of a setting spade of concrete around a post, living systems do not expend all their energy, materials and process in a burst of chemical energy. The physicist Erwin Schrödinger (1887–1961) defi ned living matter as that which actively ‘avoids the decay into equilibrium’ (1944)1 and occurs when dynamic processes reach their lowest energy states when

The current approach to the production of architecture is ancient and yet the technology that could potentially revolutionise our approach to the construction of buildings is even older than the invention of concrete. This technology is life.

opposite: Two Bütschli protocell fl asks incorporated into the Hylozoic Ground cybernetic framework. The chemical metabolisms are connected via the neural net of the responsive geotextile system as well as through the physical and chemical changes in the gallery environment. The protocell metabolisms are able to respond to heat, light and the presence of carbon dioxide produced by visitors.

below: Close-ups of the structure of the Bütschli protocells.

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the system functionally becomes inert. Living systems are able to regulate their use of energy and harness it to change their usage of raw materials over the course of a lifetime. The chemical process of taking in energy for living processes and expelling waste products is a metabolism. Through the process of metabolism, organisms are able to differentially distribute their constituent material in time and space while simultaneously releasing it into the environment.

Resisting the ‘decay into equilibrium’ – in other words, avoiding death – is so important for living systems that they continually optimise this process and even adopt new confi gurations to adapt their chemical strategies as their surroundings change. Some creatures that grow over protracted periods adopt sometimes surprisingly different forms as their needs change with their size and complexity. For example, embryonic stages enable young air-breathing organisms to respire in fl uid environments, while dramatic physiological changes are precipitated when the enlarged creature prepares for living in a gaseous atmosphere around the time of birth. Other organisms, such as the tardigrade, or water bear – the only organism that has survived direct exposure to the vacuum of space2 – may even change from an active to an inactive state when resources are poor. These different forms and chemical systems within a single organism enable living systems to continually perform this differential distribution of materials in time and space so that they can quickly adapt and respond to changes in their environment and so prolong their survival.

To produce genuinely sustainable building techniques, the materials and construction approaches need to be connected to and responsive to their environmental context3 in time and space, and may also require different forms and functions over their lifespan. The most mature technology that could perform this function is biology, but its unique chemical information-processing system, which depends on DNA, does not thrive in a city landscape. In urban environments biology is suboptimally designed for the environment and requires energy-intensive support systems to keep it alive, and is counterproductive in environmental terms. Current architectural trends to incorporate established biological systems into an urban context such as green walls and roofs require constant energy, water, artifi cial fertilisers, maintenance,

and a high upfront cost to create the illusion of a mature and self-sustaining ecosystem. Once installed, these systems are resource-intensive and require daily upkeep from external sources, which effectively outweighs any environmental benefi t they offer. Other strategies such as biomimicry where biological forms and functions are transposed into traditional material systems using a top-down design approach lose much of their relevance when their scale and materiality are changed. The result is a design solution that is inferior to the original biology being mimicked and has become little more than an aesthetic formalism or metaphor for sustainable, but essentially unworkable, aspirations within an urban context.

A new kind of biology is needed for the built environment that is native to its context and is genuinely sustainable. In order for this to happen, the basic materials that underpin this system need to be developed using a bottom-up approach. In other words, the substances that comprise the materials need to be constructed meaningfully at a molecular scale using the natural fl ow of energy in their constituents. This is a new way of creating design outcomes, which contrasts with the architectural tradition of making a blueprint to impose apparent order on a system by sheer brute force. However, nature has been taking a bottom-up approach to design for millions of years. Biology uses chemical processes to develop successive systems of organisation that are relevant to the environmental conditions, and when these change, biological systems alter their developmental strategies so that the ‘living’ solution is always relevant in the context of the surroundings. Materials that give rise to genuinely sustainable architecture must also be comprised of chemical arrangements that are ‘native’ and responsive to their environments in the same way that biological systems are.

Over the last few decades, new perspectives and models in understanding biological cell organisation have provided insights that enable us to engage with living systems in new ways so that we can design and infl uence their outcomes in an increasing variety of ways. A number of chemical systems, such as protocells, can ‘make decisions’ based on the temporal and spatial context of their internal and external conditions, and can be thought of as being capable of performing their own kinds of information processing. They may even be thought of as being ‘material computers’, which work using

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different sets of instructions and regulatory pathways to those systems that are orchestrated by DNA, the information-processing system that typifi es biology.

Protocells are very simple chemical systems that are capable of behaving in ways that we would associate with life. The mechanism of action is complex and not clearly characterised. However, it appears that the protocell provides an environment in which one set of chemical relationships is separated by a semipermeable barrier across another set of chemistries, which creates an energy gradient between the two chemical systems. In all species of protocell technology the interface, the point of contact between the two systems, becomes the place of dynamic interactions. The outcome of this relationship can result in complex structures that take otherwise inert materials and distribute them in space and time.

A simple chemical differential such as the ‘protopearl’ system, which is an oil droplet containing a metabolism that can produce an insoluble form of carbon dioxide, or a carbonate, at its surface, generates structures that resemble the structure of the oil droplet because there is no forwards movement and the crystals become deposited equally over its surface. This arrangement is observed as the system is not dynamic and the metabolism takes effect in a spatial context only at the interface of the agent, which remains globular throughout the chemical process. In contrast, droplets of sodium hydroxide in olive oil, the Bütschli system of protocell production, are highly dynamic and not only produce soft crystalline ‘skins’ at the interface, but these are stretched through the oil by the moving droplet. These skins become structurally manipulated by the physical properties of the medium, giving rise to highly complex structures. By varying the medium in which they operate and the internal metabolism, protocell technology can be chemically programmed to create a variety of surfaces and microstructures whose forms are reminiscent of biological structures. However, the protocell products differ fundamentally from biology in that they have not been produced through the regulatory system of DNA.

Interestingly, protocells do not just appear to be able to undergo transformation at the individual level, but cooperate and interact on a population scale. Protocells appear to be able to attract and repel each other and behave sympathetically,

Protocells are very simple chemical systems that are capable of behaving in ways that we would associate with life. The mechanism of action is complex and not clearly characterised.

opposite: These Bütschli protocells are in a rich environmental landscape being connected to the responsive neural net of the Hylozoic Ground installation, the chemistry of the carbon dioxide-rich gallery air and sunlight streaming in through a glass panel in the roof of the pavilion. The protocells respond to this complex landscape by producing a range of brightly coloured crystals at the oil/water interface.

below: The chemistry of the fl ask and the metabolism of the Bütschli protocells are infl uenced by the gallery environment, including natural light entering from a glass roof where the rays of sunlight are refracting into the different wavelengths of visible light through the lensing effect of the oil medium of the protocells.

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. . . a group of protocells may be attracted to each other and, after an initial interaction, produce ‘skins’ almost simultaneously, giving the impression that there is some basic chemical communication between them.

opposite: Close-ups of the structure of the Bütschli protocells. These protocells can metabolise copper salts and respond to the light, heat and chemical composition of the gallery environment, by creating structures that are a mixture of green copper carbonate and blue copper sulphate crystals which in this installation are between 1 and 2 centimetres in diameter at the oil/water interface exhibition.

below: Detail of the base of a protopearl fl ask. This protocell system fi xes carbon dioxide from gallery air into a solid crystal ‘carbonate’ form of the gas, which is similar to limestone. A ring of carbonate deposit is forming at the base of the fl ask.

bottom: The protopearl fl asks are connected to the neural net of the installation and respond to physical and changes in the environment, such as this burst of light and heat from an LED situated under the base of the fl ask.

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The group behaviour of protocell interactions in the laboratory suggests a radically different view of how living systems could organise.

below left: These protocells are created using oil droplets in a water medium, which has been drawn from the local Venice canal water. Carbon dioxide exists in solution in the canal water and also enters the fl asks in the installation from the respiratory products of gallery visitors. The metabolism of these oil droplets interacts with the dissolved carbon dioxide and converts it into a carbonate, which is a solid form of the gas, creating a pearl-like crystalline coat around it.

below right: Bütschli protocells with the same metabolism in the presence of a variety of soluble salts responding to the light and heat energy transmitted through the neural network of the installation framework by rapidly evolving and producing multicoloured small crystals at the oil/water interface exhibition.

bottom: Bütschli protocells exist at an interface and are chemically energised by the molecular interactions where oil and water are juxtaposed, providing a site for material computation which, in this case, involves the transformation of soluble salts into insoluble ones.

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conducting similar – though not identical – processes when they form a colony. For example, a group of protocells may be attracted to each other and, after an initial interaction, produce ‘skins’ almost simultaneously, giving the impression that there is some basic chemical communication between them. Additionally, these populations are capable of surprising behaviour and have been observed to undergo ‘phase transitions’. For example, two distinct protocell populations have been observed to come into proximity with each other and, after a brief initial group interaction, part in a synchronous manner while simultaneously producing long tails of crystalline material. This concerted behaviour is reminiscent of ‘quorum’ sensing bacteria, which are particular species of bacteria that can signal changes in their surroundings to the whole colony in response to information being signalled by a threshold number of interacting organisms that have detected a meaningful environmental change such as the concentration of food in that location.

The group behaviour of protocell interactions in the laboratory suggests a radically different view of how living systems could organise. It is possible for very simple chemical complexes, which are not alive themselves, to cooperate in colonies and produce emergent, sophisticated and surprising behaviours, such as growth, movement and sensitivity, that are not present in individual agents but are recognised as being characteristic of living systems. Perhaps the earliest ‘cells’ were not discrete sophisticated single entities, but more like populations of chemical complexes interacting with each other, in a similar way to the behaviour of soap bubbles or foam on the surface of water. This has important implications for the development of living materials for the built environment. It may be important to think beyond their unitary organisation of constituents and consider their emergent properties, which stem from the population dynamics of very simple units. By altering the composition of these chemistries, it may be possible to create a wide variety of different materials that are able to perform different kinds of functions.

The ability to create complex materials from simple and readily available ingredients, and evolving them into useful forms, has broad implications for the manufacturing of these materials. In particular this ‘low tech’ approach makes them accessible to communities beyond the First World, and their development in unique geographical contexts would potentially give rise to a diverse range of material ‘species’ that are uniquely designed for their particular environment. Moreover, it is possible that different species of materials are used in series to grow the biological equivalent of tissue layers around an architectural infrastructure where the growth and maturation of the structure would be in keeping with the notion of changing environments and materials with time. It is possible to consider that the multiple applications and evolution of these living materials over time and space could form an embryological approach to the construction of buildings. In this way the sequential deposition and remodelling of building surfaces

becomes a way of adapting architecture over time so that it remains relevant in the context of its environment.

Protocells can also be designed with very specifi c, unique metabolisms that can perform very particular functions that do not exist in biology. For example, over the next 10 years we will see a new generation of solar panels and cladding that can make biofuels from sunlight to help power our homes and cities, and chemically active surfaces that will actively absorb carbon dioxide and use this as a raw material that can lay down insulating protective ‘shells’ around buildings.

Let us return to the spade of concrete and imagine that it is distributed this time using protocells that are programmed to respond to light, fi x carbon and reproduce.

You take your spade of ready-mix concrete and stir it into a bucket containing a greasy solution, reminiscent of salad dressing. The solution congeals as the chemistry of the concrete is taken up into the protocell droplets, and you pour the mixture into the hole containing the post in this thickened state. The mixture swells and almost instantly supports the pole with its turgor. It now resembles a large lump of jelly. Bubbles start to appear and are quickly turned into a precipitate as the released carbon dioxide from the reaction is absorbed into a solid form. A fi ne network of greyish-white fi laments starts to knit together in the gel with the appearance of a spongy bone. The sun comes out and the fi laments appear to be thickening deeper in the hole, fi lling the darkest recesses fi rst and building up a sturdy layer of support for the pole. The hole is still full of gelatinous material but the post is now held fi rmly enough to leave the material to its own devices.

The world turns, the rain falls, the snow comes, the sun drives water out of the ground, and although the gel appears to fi ll a greater or lesser volume as conditions change, the fi laments continue to extend, bind and hold the post. By the end of the year it is time to add a new protocell material to the base of the post. This is a species of strengthening agent, which contains a different combination of chemical reagents and effectively grows around the fi laments that have been laid down by the fi rst population. You add the solution over the gel base where it seeps into its matrix and slowly, very slowly the fi laments thicken and become struts. Each year you come back to the post and make an assessment regarding what processes are required for the post to be kept in place, and each year a new protocell species is added. Gradually you realise that you are talking to the material, like you would a favourite plant, and that in many ways it is just as ‘living’ as the biology that surrounds it. 1

Notes1. E Schrödinger, What is Life?, Cambridge University Press (Cambridge), 1944, p 70.2. New Scientist, ‘Water bears are fi rst animal to survive space vacuum’; see www.newscientist.com/article/dn14690-water-bears-are-fi rst-animal-to-survive-space-vacuum.html, accessed October 2010.3. Rachel Armstrong, ‘Living Buildings: Plectic Systems Architecture’, Technoetic Arts, Vol 7, No 2, 2009, pp 79–94.

Text © 2011 John Wiley & Sons Ltd. Images © Photographs by Rachel Armstrong, 2010