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.Making Light Intelligent Among the multifarious properties and states that can be dynamically activated by smart material technologies, light stands out as a medium that, while easy to manipulate, commands a series of (quite literarily) spectacular effects. Today, I would like to share with you a project by UN Studio. The La Defence Office Complex, in Almere, the Netherlands, is an example of the application of new technologies par excellence. The attractiveness of the project relies almost entirely on the application of a special reflective film on the interior facades of the complex. The whole is kept minimalist, allowing for the color effects to occupy the foreground of the architectural experience. You may have seen similar chromatic effects on perfume bottles, or on sunglasses. The technology employed is not new, though its application at an architectural scale is unprecedented. UN Studio approached 3M to develop a multi-layer polymeric foil which is now patented and available through ChameleonLAB based in the Netherlands. The dichroic foil is composed of multiple thin layers of material with different refractive indexes. As the foil reflects light back at the viewer, the different reflected, out-of-phase rays interfere cancelling out selected wavelengths and leaving intensely iridescent spans for the human eye to behold. The dichroic layer constitutes 36 microns of the foil’s width. Together with the protective features it reaches 200 microns (0.2

mm) and can be easily laminated onto glass. Thirteen color options are available from ChameleonLAB. The foil can block light or be transluscent, depending on the design intent. We are dealing here with a new presence in architecture. La Defence Office complex becomes a scientific instrument, constantly measuring itself and the viewer against the environment - a kind of light diagnosic. Ultimately, the most architecturally interesting phenomenon in this family might be photoelasticity, since it relates material loading with color articulation (achieving load dependent chromatic effects similar to those in the UNStudio project). This and similar technologies can all be available to architecture. As the UNStudio example shows - one just needs to imagine them within reach.

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.Smart Materials ? Responsive materials are ubiquitous in their technological applications around us and many more, already developed, material ‘devices’ are waiting to be applied. Indeed, the contrast between the high specificity of available technologies and the vagueness of architectural intentions is a design problem. The overwhelming range of interactive materials becomes immediate through a cursory enumeration of some general categories. Perhaps the most well known are materials which change their spectral

properties (color, reflectivity) based on external stimuli. There are electrochromics (kindle suspended particle display), photochromics, and thermochromics, classified according to the nature of the triggering factor. With respect to other properties, we have magnetorheological and electrorheological fluids which change (usually viscosity) in response to magnetic or electrical fields. Finally, thermotrophic, phototropic, and electrotropic materials respond with changes in conductivity, transmissivity (thermooptics), volumetric expansion rates, or solubility.

Solar leaves by SMIT combine piezoelectrics and photovoltaics to harvest wind and solar energy respectively

Even though everyone has heard of them they are not at all easy to define. The concept of material smartness is ambiguous - more an approach than a designation. The blurry boundary between ‘smart’ and ‘dumb’ makes the whole affair much more exciting!

thermochromic paint finish

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The list could go on... In fact, I think it would not be an exaggeration to say that, among the general categories of physical phenomena, there are none that could not be successfully linked up by a material intelligence. In this way, light and voltage are connected by a causal relationship in photovoltaics, electric current induces a temperature gradient across thermoelectrics, movement (pressure) is transformed into electricity by piezoelectrics (based on charged dipole composition of the material). There are photoluminescent materials which respond with light to light (often shifting the spectrum, for example, from UV to visible), and though the term photoelectric is reserved to a physical phenomenon of absorption and emission of importance to (the history of) general relativity, I see no reason why it would not be fit to describe the materials that emit light when stimulated by a current - as is the case for a usual bulb (or rather the metal wire within). In some cases the stimulus affects the molecular structure of the material and changes its properties. In others, the material acts as an energy converter, passing on an equal amount of energy in changed form (from current to light and heat, for example). Perhaps the simplest cases involve materials where the input is not altered in quality but rather limited (or expanded) in its amount or spectrum. Numerous optical examples come to mind: from simple polarization devices, through

radiant color films (where the color of transmitted and reflected light depends on the vantage point), view directional films, mirror films, and image redirection films. Furthermore, individual materials, whatever their properties may be, can be combined into more complex technologies, which are nevertheless usually based on the same simple stimulus-to-effect relationship.

radiant color (dichroic) layer applied to glass

Additionally, many of the material devices allow for ‘reversible causality’: piezoelectrics allow for both, shape-change to current, and current to shape-change transformations. Similar to the piezoelectric materials are the shape memory alloys (SMA) which also operate in reversible cycles. Usually titanium-nickel alloys, they are very flexible unless above a certain temperature, when they undergo a molecular transformation and return to a ‘remembered’ shape. A simple example of SMA is the Hanabi Lamp by the Japanese firm Nendo which uses the heat of the bulb to ‘blossom.’ When reversibility is not possible within the confines of a single material there are usually different technologies that allow to make the link and complete the causal cycle.

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Hanabi lamp

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Computationally controlled AEGIS Hyposurface (left) and ‘Warped’ by Matt Hume where veneer panels shrink and expand depending on air moisture content, creating movement within the assembly (above)

We could proceed further in accordance with the wide conceptual framework already established. Looking at more commonplace examples (and this is where productive confusions come in) one could of course notice that any material could be considered more or less ‘interactive’ or ‘smart.’ A simple rock, the epitome of inertness, successfully reflects light limiting its color spectrum, weighs down on the ground (thus interacting with other matter), exhibits thermal expansion, and finally, is home to many more or less ‘smart’ processes of chemical transforma-

tion, to name just a few. Ultimately human creativity is the sole judge of material ‘smartness‘ and arbitrates between exciting responding and mere withstanding.

puting unit or a human agent. An interactive material often needs to be ‘plugged’ into a system in order for the effects to have import on the building scale.

From the perspective of a designer considering the variety of smart materials and their potential for agglomeration, it is useful to think of them as free floating links that can be arranged into more complex technologies. The networks thus created can be more or less deterministic – the flow of affect (or information) can be redirected via switches, offloaded to a com-

Even though the ‘dumb’ smart materials (or the simplest techno-material networks) are perhaps most elegant, there may be no essential criteria to distinguish them from the other assemblies. Indeed, though computers may be perceived to divert techno-material systems away from ‘honesty of expression,’ they themselves are based on nothing else but these

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elementary material units (in all their ‘truthfulness’!). From this perspective, the computer ‘zeros and ones’ become merely an operational abstraction overlaid on top of electric impulses. There is no real reason to avoid the former in techno-material assemblies unless one is prejudiced against their ubiquity, versatility, and tendency to allow for extreme (computational) complexity. In the end there is no difference between the electrically and the environmentally triggered materials (energy

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losses in the former case are ultimately marginal). The cybernetic metaphor of pervasive intelligence affects things on both sides of the spectrum. ‘Smart’ is also ‘cyber.’

in the case of the computer, however, it encapsulates material intelligence into a closed ‘ready-made’ and whose application lacks the thrill of spinning life into dead matter of some other technologies.

In this way, it may be interesting to point out that it is precisely the material devices described above that allow physical phenomena to enter the electronic circuity. Piezoelectric materials serve as sound sensors (and are incorporated into all kinds of ‘buttons’). Light is detected with materials that change resistivity, or create an electric current when illuminated. Changes in temperature can be registered by the degree of bending of a bimetallic strip with two different thermal expansion coefficients, etc., etc. The digital (and, by extension even the virtual) is just an aspect of the material.

The realization that in our age and time, where nano- meets cyber-, the conceptual boundaries are fluid, allows us to revise our approach to architecture. Beginning simple perhaps, and taking into consideration the above, we could say that architecture has never properly dealt with the issue of tectonics - suppressing the most essential behavior of materials (thermal expansion) rather than expressing it... ...don’t hold me to this - just wondering...

What about nature? As a repository of liveliness, it is hard to avoid as a metaphor for artifacts that react to environmental conditions anyway. Indeed, many already mentioned examples immitate nature in a gesture of biomimickry. In general, however, ‘reinventing the wheel’ is unnecessary. Rather than mimicking biological interactivity with new materials, one can also simply quote nature with results that, I would argue, can still be understood within the smart material paradigm. Your usual green-wall is ultimately a very complex material assembly alive with a network of chemo-physical processes. Perhaps as

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chevron thermal actuator is a micromechanical device used to augment the displacements due to thermal expansion

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Making Light Intelligent