Philip Beesley of Waterloo Architecture will present recent work by the Living Architecture group, including projects from the Hylozoic and Epiphyte series of collaborative projects. Working with artists, engineers and scientists, the research collective combines the crafts of lightweight textile structures, dense arrays of distributed computer controls with machine learning, and early systems of artificial-life chemistry. New architectural installations within the collaboration feature dense reticulated grottos with breathing, reactive, near-living qualities. Details from the emerging work show a preoccupation with intimate human touch interacting with extremely lightweight materials diffusing into the surrounding air.Thin layers of voided hovering filters are tuned for delicate kinetic and chemical responses that cohere in the form of expanded physiologies, beckoning and sharing space with viewers.
The presentation will suggest that conception of buildings can move from classical ideas of a static world of closed boundaries toward the expanded physiology and dynamic form of a metabolism. The architecture of historical Humanism encouraged stripped surfaces supporting free human action. Yet need we say that the boundaries of my body lie only at our skins and that the boundaries of a building must be defined by an enclosing envelope? My clothing floats and ripples outward. Fluxing heat and cold cloaks me. The systems that appear within life-giving forests and jungles seem opposite to the rigid, stable enclosures of classically defined building. Instead of valuing resistance and closure, design for thermal exchange could result in new form-languages based on maximum interaction. Architecture could be founded on adaptation and uncertainty where acquiring and shedding heat play in uneven cycles. The densely layered forms of a jungle are often made of diffusive, deeply interwoven materials that expand and interact with their surroundings. The kind of diffusive forms seen in reticulated snowflakes and the microscopic manifolds of mitochondria have a common form-language of radical exfoliation. Their increased surface areas can make their reaction-surfaces potent. These kinds of forms offer delicacy, resonance and resilience.
Writ large, these forms speak of involvement with the world. A new city designed to easily handle unstable conditions of shedding heat and cooling, and then rapidly warming up and collecting heat again, might well look like a hybrid forest where each building is made from dense layers of ivy-like filters and multiple overlapping layers of porous openings. A building system using an expanded range of reticulated screens and canopies is implied, constructed from minutely balanced filtering layers that can amplify and guide convective currents encircling internal spaces. Within this renewed city fabric, the thermal plumes surrounding clusters of human occupants offer a new form of energy that could be ingested, and diffused, and celebrated.

In nature, water acts as an invisible support as well as a shape-forming system. Its function is to mediate between internal chemical processes and external environmental stimuli. It assembles basic molecules into structures with complex functionality characterized by nano to macro property variation such as the one found in the beak of the giant squid where its content contributes to stiffness gradients. In contrast, digital fabrication and manufacturing platforms are generally characterized as unifunctional, wasteful, fuel-based and often toxic systems.
This paper explores the role of water in nature and proposes a water-based digital fabrication approach for the design and fabrication of highly sustainable products and architectural parts made of regenerated biomaterials and natural polymers. The paper demonstrates that hydration can be harnessed to grade mechanical, optical and environmental properties of materials through a novel additive manufacturing platform and exemplar products. The paper will include three prototypical cases in which water is used to (1) initiate shape fabrication (2) activate shape formation and; (3) inform material organization and behavior.
A multi-axis robotic arm serves as the base platform for the development of a water-based multi-nozzle extrusion system. The deposition system will be designed to 3D print an array of natural polymers such as chitosan, alginate, starch and cellulose all of which can be graded and processed to form extrusion-compatible gels. Experimental and computational predictive modeling methods with special focus on numerical analysis of non-linear hydration-informed mechanical tenability is implemented. Applications of the system include small-scale recyclable objects and temporary medium and large-scale architectural parts.

Using insights gained from interfacing cells with active, geometrically-defined soft materials in a 4-D setting (spatially and temporally), we design and engineer materials for responsive skins for building facades based on hierarchical polymeric pillar arrays. Surfaces patterned with periodic nano- or micro-scale features are utilized for a wide range of applications, for such purposes as controlled wetting, adhesion, optical elements, microfluidics, etc. In particular, wrinkled surfaces can serve as a versatile platform for fabricating hierarchical, dynamically-tunable surface patterns. We demonstrate a facile and flexible design for the pattern confinement of mechanically tunable wrinkling in a poly(dimethylsiloxane) (PDMS)-based system. 1D wrinkles can be fabricated by uniaxially prestrained PDMS substrate, followed by oxygen plasma treatment. We investigated the wrinkle formation confined to the square arrays of microposts; in particular, we are able to fabricate tilted pillars atop wavy wrinkles. The transparency and coloring of the film can then controlled by the reversible tilting of the micropillars using mechanical force. Alternatively, spray-coated quasi-amorphous arrays of silica nanoparticles were used to form angle-independent colored films. The color of the films can be tuned by controlling the parameters of the particles, the film thickness and the spray coating. By embedding the particles within PDMS and inducing wrinkle formation, tunable optical windows with various hierarchical patterns can be fabricated. In this case, we can encode messages using the sprayed nanoparticles, which can be revealed upon stretching. The morphology of these hierarchically-patterned substrates can be controlled reversibly using mechanical force. Both approaches form substrates that are versatile materials for controlled, switchable transparency, adhesion, and wetting.

Previous work has shown that bio-inspired compliant mechanisms derived from various plant movements, can be transferred to flexible constructions in architecture. These deformable systems, however, challenge our basic understanding of mechanics as they often result from a complex interplay between geometry, structure, elastic material behavior, boundary conditions, and types of actuation. Balancing these sometimes-contradictory influencing factors is of crucial importance since they affect a system&’s motion behavior and performance range significantly. Already small imbalances can have drastic effects and may entail unpredictable consequences. For a designer, a target-oriented optimization to one specific task poses therefore a major challenge due to the many functional-morphological interdependencies and correlations within the system. While the high degree of complexity and large number of parameters may be undeniable disadvantages, they can also be seen as opportunities. It enables design variability and opens the door to a larger domain of solutions.
To support this hypothesis, this paper will propose a more holistic approach to the design of bio-inspired, flexible structures and materials. After a brief summary of why their use in architecture can be generally beneficial, the authors will introduce a specially developed modeling environment for their design, analysis, and synthesis. This digital framework integrates different levels of information into one design process. By combining various actuation types with different techniques to simulate large structural deformations, this interactive framework relates cause and effect and allows for further investigations. The potential of this approach will be demonstrated in more detail on the example of two plant-inspired mechanisms that were subject to earlier studies.
The elementary principle of functioning in the flower opening of the Lilium and the trapping motion of the Aldrovanda will be used here as parametric master-models based on which a series of variants will be generated. By assigning a basic actuation type and further defining material properties and boundary conditions, one can simulate the deformation movement, stress distribution, and performance ratio of the different models. The results can be filtered and compared to each other and thus allows to make better-informed decisions for the further improvement of the mechanism. By modifying the initial setup or by recombining the characteristics of capable sets, one can additionally use this framework to generate improved or completely new solutions. As a result one can begin mapping the potentials and limitations of various action types in respect to specific functional-morphological features. This renders the possibility for far-reaching explorations of the design domain as a whole, beyond the mere copy of the biological role model, which may ultimately inform new flexible structures and materials.

Reconfigurable metamaterials that can bend, fold, or transform the shape in response to external stimuli have attracted significant interests in design of flexible electronics, color displays, smart windows, actuators, sensors, and photonic/phononic devices. First, we show the fabrication of tilted polymeric pillar arrays and colloidal particle dispersions, which can change the optical properties from opaqueness to colorful display to transparent windows in respond to environmental cues, such as proximity, touching, heat and light. By coupling the materials-environment response at the nano- and microscales with CMOS technology, we demonstrate adaptive building skins with autonomous tracking/imaging/sensing ability and feedback control systems. Using kirigami (cutting + folding) principles, we cut and fold extrinsically flat and rigid (incompressible) sheets from paper and polymeric materials. By introducing fractal cuts of various motifs, these sheets exhibited dramatic shape change (e.g. ~800% areal expansion) and super-conformability via expanding or collapsing of the periodic hole arrays. It allows us to integrate conventional rigid devices (e.g., LEDs, circuits, and RF antenna) onto such sheets without sacrificing device performance during stretching or collapsing. Further, we explore and develop kirigami rules to fold the 2D sheets into targeted 3D structures with carefully placed cuts.

Elastic and conducting nanocomposites can become important building blocks for the next-generation multifunctional materials combining electronic, energy harvesting, and load-bearing functionality. Current research efforts in strain-engineering of nanocomposite have been focused primarily on the atomic, molecular, and nanoscale structural elements of these materials. Here we look into controlling defects, borrowing concepts from kirigami, a Japanese paper cutting technique. We carry out a systematic study of the mechanical response of assembled nanocomposite sheets patterned with periodic arrays of microscale cuts guiding stress concentration and distribution. Using finite element analysis we probe the mechanisms underlying this pseudoplastic response and show that stress is delocalized around the cut defects, resulting in superior damage tolerance. We show that kirigami can enable the fabrication of highly elastic composites that retain ~99% of its conductivity at high strains (~300%). Finally, we establish a systematic framework to predictively control mechanical properties by geometric parameters, which leads to a novel materials design paradigm - one focused not just on the constituents and their arrangement, but also on how their hierarchical structure affects deformation mechanics and its relation to other functional properties.

Photocatalytic coatings, primarily based on titanium oxides (TiO2), are being increasingly incorporated into architectural materials due to beneficial functions such as self-cleaning of the coating surface and decomposition of pollutants and bacteria which come in contact with the coating [1]. Once the photocatalyst is incorporated into the building material, it functions passively without any external control, as long as there is enough ambient optical radiation that can excite it. The objective of this research is to investigate whether functioning of the photocatalytic coating can be controlled and enhanced by using external electrical means. Two types of control are envisioned. (a) Provide electrical charges to the photocatalyst to accelerate surface reactions, namely oxidation/reduction of gases in contact with the surface. This function can be introduced by embedding the photocatalyst in a conductive matrix and connecting the conductor electrically to ground. (b) Apply an external electric field to the photocatalytic coating so that ions and radicals produced on the surface can be released to the environment with the help of the field to scavenge pollutants in air. This function can be accomplished by connecting the conductive matrix mentioned above, not to the ground, but to a voltage source that sets up the field. The impact of the presence of an extra charge or an electric field on the functioning of the photocatalytic processes are investigated by first principle quantum mechanical calculations. The method used is DFT with B3LYP functional and Pople type basis sets augmented with polarization functions. Atomic models consist of various atmospheric gases like oxygen (O2) or water vapor (H2O) interacting with the surface of an anatase type TiO2 material. Optimal positioning of the gas molecules with respect to the TiO2 surface is calculated with and without a +/- charge or an electric field of magnitude 0.001 au perpendicular to the surface. An interaction energy is derived for each type of gas and for each set of electrical conditions based on the results. Calculated results are as follows: (a) Interaction energy for O2 is 0.5 eV with zero charge and no electric field, 1.0 eV with -1 charge, 0.4 eV with the electric field. (b) Interaction energy for H2O is 1.2 eV with zero charge and no electric field, 1.4 eV with +1 charge, and 1.2 eV with the electric field. Results suggest that it is possible to influence the functioning of the photocatalyst by both methods. Interaction of other ambient gases (nitrogen, carbon dioxide, etc.) with the TiO2 surface are being analyzed under similar circumstances and additional results will be reported during the presentation. [1] K. Hashimoto, "TiO2 photocatalysts towards novel building materials," International RILEM Symposium on Photocatalysis, Environment and Construction Materials, October 2007

Efficacious resource harvesting constitutes new modes of conceptualizing the interactions of buildings with surrounding environmental conditions. The internal logic of a biotechnical paradigm in architectural design allows for the potential of fluid exchanges between medium and material to be realized with correlated metabolization. Such concepts avert existing mechanical paradigms based upon linear conservation of energy processes and approach entropic integrated design interactions of nonlinear dynamical processes. Through a physiological analogy that informs architectural anatomy, the genetic code of hydrogels embeds emergent morphological responses to discrete interactions with environmental phenomena. In contrast to the static hard tissue of the skeletal system, viscoelastic soft tissue provides significant environmental impact by means of integrating spatiotemporal adaptation in building systems.
This framework provides an interscalar perspective for integrating biopolymeric membranes within building-envelope systems and informs the microstate design of the polymer chains for optimized mechanical performance. Hydrogels are a translucent three-dimensional water-swollen polymer, which exhibit mechanical work upon interaction with water vapor. In effect, this interaction provides for a variant index of refraction, a variant heat capacitance, and a physical shift in surface morphology. Characteristic changes in material thermal and mechanical properties parallel diurnal climate profiles for circadian biorhythmic membrane designs. The macrostates of temperature, pressure, and volume reciprocally inform the potential microscopic properties, including position and velocity of each molecule within the material system. The viscoelastic molecular entropy (Maxwell relation) of hydrogels is established as a fundamental basis for situating a dynamic material logic influencing a high efficacy architectural physiology. The Maxwell relation is translated as an algorithmic framework for mechanical control through tetra-functional polymer chain development of biopolymeric hydrogels. In contrast to polyacrylamide hydrogels, the chemistry of biopolymeric polysaccharide hydrogels is well suited for renewable sourcing and down cycling to achieve sustainable material life cycles. However, these biopolymers do not inherently exhibit robust structural properties necessary for influencing morphological shifts of the membranes for intelligent passive design strategies such as self-actuating ventilation apertures or self-shading surface geometries. The research encompassed in this work engages the development of a more acute framework for the trajectory of biopolymeric hydrogel dynamics based upon a necessity for controlled morphological modulations in response to specific environmental conditions.

Harvesting ambient energy from humidity gradients is an attractive approach to design remote devices and regulators. Embedding logic and feedback within the component materials and geometry simplifies design, reduces sensor demand and ultimately points toward autonomic material systems (i.e. smart composites). The challenge however is to understand the interdependent correlation between geometry (i.e. boundary conditions), material composition (i.e. mechanical properties, absorption rate), and external energy gradient (i.e. humidity gradient profile, rate). To address this challenge, a polyimide - sulfonated poly(amic acid) copolymer system was developed, where mechanical responsivity in a humidity gradient can be tuned via composition and spatial patterning. Oscillatory (~1 Hz) motion of monolithic films in inhomogeneous gradients can be understood via conventional bilayer swelling and predicted via mechanical analysis. More complex actuation and location can be designed by prescribing sample geometry, and “printing” an absorption rate pattern across the film by local laser anneals to control the conversion ratio of PI-(ester-sulfonyl) to PI-(carboxylic acid). The excellent thermal stability, fatigue behavior and chemical resistance of polyimides provide materials with outstanding mechanical integrity, demonstrating >100 oscillatory and locomotion cycles without performance degradation. The combination of co-polymer synthesis, local patterning and mechanical design provides a novel platform to combine mechanical responsibility and feedback control within a single material system.

How can the field of architecture take knowledge from another discipline, yet apply it from within? In the past, the approach has been one of extension—the umbrella of the discipline was extended to overlap with other fields such as structural engineering and construction. But the disciplines we must look to today in order to make any substantial headway are far beyond our normative collaborative partners. Furthermore, many of these other disciplines have seen significant changes over the last few decades, both in content and in method, that have far outstripped the pace of technological change and adoption within the field of architecture. There is no field in which the disjunction between architectural application and disciplinary evolution is as acute as it is in Materials Science. The material lexicon in architecture has always been grounded in artifacts—we treat materials as things even insofar as they might have a performative function. Walls, cladding, floors, structure, glazing, and insulation are our knowable and tangible entities, and each entity has a finite set of material alternatives. As Materials Science has evolved, and material properties have expanded from high performance to engineered to smart to programmable, the resultant materials have entered into architecture through the lexicon of artifacts, and, as such, are treated as substitutes, albeit ones that might bring an added functionality. Hence we see a performative wall or a kinetic wall or a responsive wall, but not the elimination of wall through the design of transient micro-energy exchanges. The real opportunity for a true inter-disciplinary exchange would be one in which the very nature of how materials are used in architecture is open to question.

Despite recent advancements in digital fabrication and manufacturing, limitations associated with computational tools are preventing further progress in the design of non-standard architectures. Conventional computer-aided design tools typically contain geometric and topologic data of virtual constructs, but lack robust means to integrate digital fabrication constraints and material properties within virtual models. The paper postulates that higher degrees of overlap between and across media result in highly efficient design manifolds and systems able to better mediate between physical matter, environmental constraints in order to achieve desired functionality across length scales and over time.
This paper will set the stage for a new theoretical framework and an applied approach for the design and fabrication of geometrically and materially complex functional designs termed Fabrication Information Modeling (FIM). We will demonstrate systems designed to integrate form generation, digital fabrication, and material computation starting from the physical and arriving at the virtual environment.
The paper will review four computational and mathematical strategies for the design of custom systems through multi-scale trans-disciplinary data, which are classified and ordered by the level of overlap between the modeling media and the fabrication media: (1) the first model takes as input biological data and outputs 3D printed digital materials organized according to functional constraints; (2) the second model takes as input geometry and environmental data and outputs robotically wound fibers organized according to functional constraints; (3) the third model takes as input material and environmental data and outputs CNC deposited pastes organized according to functional constraints; (4) the forth model takes as input biological, material and environmental data and outputs robotically deposited polymers organized according to functional constraints.
The paper will validate the potential of FIM through fabricated products and present advantages over traditional approaches. We will present a multi-scale model to design and fabricate an articulated body armor informed by skin strain fibers, and a heterogeneously structured architectural panel informed by environmental feedback. The results will demonstrate the FIM approach and point towards its value to design and designers who seek to inform their work through multi-scale trans-disciplinary data, a capability that is currently missing from standard design-to-fabrication workflows.

This research focuses on defining the design principles that integrate passive-system thinking into the built environment with the goal of mitigating building energy usage by self-regulating the heat gain/loss at level of building envelopes. In collaboration with a company that developed and uses advanced Ultra High Performance Concrete (UHPC) integrated with mold design and manufacturing of architectural elements, our research targets how specific manipulation of UHPC surface area in combination with self-regulating thermochromic response can improve building&’s energy performance. By coupling the adaptive color response with surface geometry we can suggest new passive sustainable solutions that would mitigate the energy usage with no additional energy input; purely through designing the form and color adaptation for UHPC concrete Trombe wall components integrated within building faccedil;ade systems.
This presentation will outline the investigation of how the thermochromic treatment of UHPC surface (temperature induced color change reactive to natural environmental fluctuations) coupled with surface geometry effects the rate of heat transfer. Understanding the thermal behavior in response to scale, form and color of architectural components is critical, and will help us define new design strategies that can lead to a simple and exciting design solution applied to building facades and passive thermal mass systems. Such knowledge not only enhances the possibilities within architectural design, but becomes an effective strategy in self-regulating the heat gain/loss at the building surface level, while reducing the need for mechanical building systems.
This research builds on a previously validated body of work that operates under the premise that complex geometries can be used to improve both the aesthetic and thermodynamic performance of passive heating and cooling systems. The focus is on a deeper understanding of how specific morphological manipulation of mass distribution to surface area affects the rate of thermal transfer and how the surface area geometry can become an effective agent in energy collection, throughput, storage and re-radiation of sensible heat. Using patterning techniques constrained by genetic algorithms and coupled with advanced digital and physical thermal simulations, we define basic design strategies and test physical components that would lead to new way of thinking about the role of morphology in energy focused design applications. This body of work operates under the premise that complex geometries can be used to improve both the aesthetic and thermodynamic performance of passive heating and cooling systems.

In the context of high-performance building envelopes, emerging nano- to micro-material innovations are fundamentally shifting current expectations of dynamic building envelope functionality towards systems that can simultaneously respond to occupant needs and preferences while meeting the energy demands of buildings. Until this point, there haven&’t been building facade technologies that have provoked the engagement of occupants to the degree that they offer now. New materials can respond simultaneously to environmental inputs and interact so subtly or explicitly to the design and comfort preferences of individual occupants. The recent transfer of nano- to micro-electroactive material technologies for dynamic glazing systems that intelligently adapt to fluctuating bioclimatic conditions has led to improved building simulation tools for measuring their daylighting and solar control capabilities. Although emerging research provides tremendous potential for future systems, it primarily focuses on energy efficiency and continues to postpone human factors issues. Even the most advanced simulation tools for quantifying optical and energy performance are currently unable to simulate both the range of multifunctional material behaviors and their response to the diverse visual and aesthetic preferences of occupants. These challenges have limited the criteria for testing novel material systems that mediate fluctuating bioclimatic flows while co-optimizing their response to meet the comfort requirements of multiple people inhabiting shared indoor environments. In order to assess the architectural opportunities of nano- and micro-material innovations for building facades, new simulation tools are needed to predict and program their multifunctional performance capabilities. This paper describes the construction and experimentation with augmented reality simulations for co-optimizing advanced building skin performance according to occupant and bioclimatic response. Multi-scalar and multi-dimensional simulation methods provide invaluable support to the research and development process on several levels. First, by constructing immersive visualization environments that simulate the behavior of intelligent materials at full scale for human factors testing, the feedback and analysis can inform the reiterative material prototyping process with valuable user input early on in the development process. Second, simulations are critical for understanding the impact on energy and information performance from human interaction and occupancy behavior patterns, as well as on overall system performance, particularly through preference for certain aesthetics effects. Both the strengths and limitations of the augmented reality simulations in balancing environmental performance and human interaction are discussed. Conclusions present areas of ongoing work integrating multi-user interactions and immersive visualization techniques with whole-building energy modeling tools.

The current era can be characterized by technological progress advancing at a pace never seen before. Due to these and other advancements the world population will continue to grow until at least 2050, reaching in between 8.3 and 10.9 billion people. More people will not only need more resources, including food and energy, but especially space to live. Considering that by mid century over 70% of all people on the planet will have moved to cities the question arises on how to address these tendencies while aiming to prevent the creation of vast suburban zones or even slums. At the same time current and future generations, who are born into a digitally enhanced world, might develop new needs and expectations towards living environments that go beyond aspects of shelter and privacy but might include virtual environments or uncommon means of communication and exchange. While other industries, like the automotive, aeronautic, and especially the consumer electronics sector invest heavily in trend research and demographic studies, constantly probing visionary concepts and futuristic scenarios, the building industry remains relatively slow and conservative in realizing novel ideas. Whereas this can be understood considering the scale, longevity, economic value, and time it takes to make a building it doesn&’t mean that the concepts aren&’t there, maybe just not well enough appropriated to the current context. One very common possibility to address change, progress, and uncertainty is flexibility. As things change, you change with them; rather than retrogressively fighting progress you mutually evolve and adapt. Jonathan Hill describes three methods to achieve architectural flexibility: spatial redundancy, mechanical transformation, and flexibility as a political statement, yet in regards to the current technological situation I believe that one more possibility can be added: flexibility by adaptive materiality. Adaptive materials have the ability to respond to external impacts in a controlled and easily perceivable way and offer unprecedented possibilities for the creation of responsive and flexible environments. Yet unfortunately their availability and the knowledge on their behavior is rather limited. In order to provide access to such materials and distribute information on their operation, structure, history, context, and application, but especially to inspire and create a common ground for discussion and exchange the materiability research network was established in 2012. The open community platform forms a continuously growing database on a wide range of materials, offers hands-on tutorials to self-produce them, and promotes their assembly in speculative projects. This trinity, information, instructions, and inspiration is ought to help develop a common language to cross-disciplinarily bridge the gap between research, education, and practice and thus progress the development of adaptive materials tailored for a possible architecture of the future.

Stigmergic Fibers tackles the prospect of moldless fiber aggregation to produce controlled material and spatial morphologies. A robotic fabrication methodology is investigated, shifting from a top-down to a bottom-up design process, which begins from the emergent fiber aggregation effect in micro scale and end with a particular tool-based fabrication process, speculating, testing and building up a“tool-material interaction” model to guide the design protocol at the architectural scale.
By means of air pressure we separate the fibers from a roving allowing them to self-organize and re-assemble due to the surface tension caused by a fine mist of adhesive. This creates a controlled fibrous aggregation producing an emergent morphospace encompassing the initial substructure.
Designing an end effector for the robot to precisely spray the fibers allowed us to predefine the spraying protocol of any object, like a 3d printer for fibrous material, while also modifying the material properties at each of its parts. Varying degrees of material density, thickness, and rigidity could be achieved by simply adjusting certain parameters in the spraying process while always ensuring repeatability and precision.
Multiple raw materials are investigated. Natural hemp fiber gives a good tension strength with translucent appearance, while a mixture of natural fiber and conductive fiber introduce electronical property to the sprayed material. By using an external Swept Frequency Capacitive Sensing Circuit, the aggregation works as a large-scale multi-point touch sensor. Capacity and Frequency changes can be mapped and used to control actuators.
The method creates an environmentally sustainable and programmable three-dimensional textile that can be applied with minimal supporting structure. Controlling the tool path, coupled with the environmental, thermal, conductive nature of the fibers used, opens up a wide range of applications ranging from interactive building envelopes, decorative insolation, to custom made fashion.
An extremely lightweight, free-standing pavilion was fabricated. Natural fiber and conductive fiber are sprayed on pre-bend 2mm diameter carbon fiber rods, creating a hybrid tensegrity structure, in which fibers work as tension element and carbon fiber rods work as active bending(compression) element. Like a living skin in architectural scale, this pavilion can sense the amount of people touching it and change color with addressable LED lights.

The ability to mix concentrated viscoelastic inks “on-the-fly” represents an enabling advance for 3D multimaterial printing at the microscale. The mixing efficiency of passive and active microfluidic printheads is directly observed over a broad range of experimental conditions. While passive mixing is insufficient, active mixing can be successfully achieved by controlling the flow rate and mixing speed of viscoelastic inks within these microfluidic printheads. Simple scaling relationships are developed to predict the printing conditions required for uniform mixing of these inks. Building on this fundamental knowledge, we demonstrate multimaterial 3D printing of model inks composed of different colors as well as reactive two-part epoxies.

Asymmetric structures, such as ratchets, slanted pillars, have been utilized in micro-fluidic devices or bio-inspired adhesives, etc. To realize asymmetric nano- or micro-structures, UV exposure on photo-active materials with an angle or oblique plasma etching is exploited. However, those methods have difficulties in optimizing the process conditions and they need special equipment. These days, 3D printing technology has emerged as a promising tool for fabricating complex structures including asymmetric structures. In this presentation, we will deal with two approaches to fabricate asymmetric structures with programmable materials. First, a replica molding should be the easiest way to realize the asymmetric structures. After realizing asymmetric structures with 3D printing, we prepare a PDMS replica mold from the asymmetric master mold. Then, we could fabricate asymmetric structures with programmable materials from the PDMS mold. Second method is direct 3D printing of programmable materials. We will compare two approaches and demonstrate some applications in various areas.

In this study, a single fiber pull-out test of 3D printed fiber-reinforced composites is theoretically, computationally and experimentally investigated. A multi-material 3D printer was used for prototyping specimens consisting of nanostructures embedded on a fiber within a matrix. Several 3D Printed specimens were tested and the interfacial strength was evaluated as a function of distribution, orientation and geometric features of the nanostructures as well as the stiffness mismatch between the fiber and the matrix. Fiber and the nanostructures are comparatively stiffer than the soft polymeric matrix. It was found that the fibers with embedded nanostructures has higher strength than the ones without nanostructures. The orientation of the embedded nanostructures significantly influences the interfacial strength for a given distribution and geometric feature of the nanostructures. Experiments on 3D Printed samples indicate that the interfacial strength can be significantly improved by engineered design of 3D architectures of embedded nanostructures on the fibers. Motivated by these experiments, a theoretical framework is developed to analyze the micromechanics of stress transfer in a fiber pull-out test. The 3D Printed assembly was idealized as a three layered axisymmetric system representing the fiber, embedded nanostructures and the matrix. Embedded nanostructures are represented by an effective interlayer. All three layers are regarded as linear elastic isotropic continua. The effective interlayer is considered either as an inhomogeneous or a homogenous interlayer depending upon the distribution of embedded nanostructures along the fiber axis. The traction-free boundary conditions, and the continuity of stresses at the interfaces are strictly enforced. All the stress components in the entire assembly are expressed in terms of a single unknown stress function. The governing equation of the problem is obtained by a variational method in conjunction with the principle of minimum complementary energy. A systemic parametric study was conducted to evaluate the pull-out strength as a function of stiffness mismatch between fiber and the matrix and the geometric parameters. Finally, single fiber pull-out test was also simulated numerically using Abaqus FEA version 6.12. It was observed that the pull-out strength obtained from experiments, theory and FEA agree well with each other. This study provides insight into the design nanoengineered composites.

Time is very illusive and most of us experience it subjectively as it defines every moment of our lives. To see if time passed or not we need to encounter change in our surroundings. Before the advent of contemporary time measuring devices the observation of nature&’s predictable cycles such as changing seasons or the diurnal motion of celestial bodies was the predominant way of measuring the passage of time. Even though we now have precise measuring devices our temporal reality and biological rhythms are still shaped by experiencing changes in our immediate surroundings.
Quartz clocks that make use of piezoelectric crystals give us precise time measurements that only have a discrepancy of a few seconds per year. These crystals belong to a class of materials called smart materials. The intriguing substances can react to external stimuli with a very specific material response and are deeply rooted in the four dimensions. When the crystals are exposed to an electric current they vibrate with a very specific frequency that allows us to accurately determine the passage of time.
But smart materials that are firmly anchored in the time-space continuum that shapes our lives can react to a variety of stimuli besides electric currents. They can range from thermal differentials, photons of light, chemicals, or mechanical stress. The material output can include changes of shape, volume, color or luminescence.
Emergent materials that are being advanced on the nanoscale in order to improve the material performance (output) as well as the varying stimuli that they accept (input) are gaining more attention in architecture. They can be designed to address specific issues in the constructed environment like the unpredictable nature of a changing climate. They can assist in creating resilient, active and reactive architectures that adapt over time to meet our future needs.

Mark Goulthorpe, architect at MIT, will describe on-going research into thin-skin thermoplastic building envelopes. These use an innovative continuous-feed composite manufacturing process that combines with CAD-CAM processing to offer a versatile new design>build protocol. The research is being carried out jointly by several academic and several industry groups, with the shared goal of evidencing an alternative building technology that targets developing world markets initially, principally housing. The research also looks to quantifying the benefits of such new material-processing, mapping out detailed life cycle analyses that testify to a remarkably benign environmental footprint, and witnessing the resilience and greatly reduced lifecycle "footprint" that such process might offer. The goal is a radically streamlined methodology for executing high-quality and variable (non-standard) buildings, well-suited to stringent conditions where there is extreme climate or little water, or earthquake and flood conditions. Given the stringent need for buildings in the developing world, which seem destined to create an unprecedented environmental pollution and resource depletion in the coming decades, so the research hopes to suggest a radical yet entirely plausible alternative, where economy of production and minimal environmental impact seem mutually dependent. The presentation will also outline the challenges of such an approach, particularly in respect of compliance with extant building codes, which may need to evolve to suit the new material/processing paradigm.

Recently, periodic nanostructure arrays have been extensively explored for photonics, plasmonics, photovoltaics and sensors, etc; however, majority of these structures are fabricated with complicated techniques which comes with a low patterning speed, small patterning area or high processing cost. For example, nanosphere lithography is commonly employed but the nanospheres are only used for once and then sacrificed in the pattern-transfer procedures, leading to the high labor input and materials consumption as well as lowered controllability and reproducibility. In this work, we demonstrate a simple but reliable photolithographic technique, which allows the rapid fabrication of periodic nanopatterns by employing surface-textured soft polymer films as optical masks for the area selective exposure of photoresist upon flood UV illumination. Geometric characteristics of the obtained nanopatterns can be controllably manipulated by varying the mask design, photoresist thickness and exposure dose. Instead of a single usage, the polymer mask can be used for numerous times without noticeable distortions in the achieved patterns. More importantly, the versatility of this lithographic approach can be validated with the fabrication of well-ordered nanoarrays of Au disk and ring, which support well for the surface plasmon oscillations, constituting an exciting platform for various technological applications, especially in the area of low-cost, label-free chemical- and bio-sensing.

We reveal how origami-based folding structures are an ideal platform for programming multistability into the microstructure of a material. Our focus is the simplest possible building block---rigid 4-vertices---which we demonstrate are generically multistable and can have up to six stable states. With a simple algorithm, we are able to program the stability landscape of a single vertex into an extended fold tessellation. The resulting metasheet has as many stable homogeneous shapes as the base vertex, but also gives rise an exponentially growing number of stable heterogeneous shapes. While our focus is on Euclidean vertices, our results are equally applicable to non-Euclidean ones and "3D origami", opening the door to yet more functionality. We envision applications ranging from deployable architecture to micromechanical devices to dynamic and adaptive optics.

Dynamic structures that respond reversibly to changes in their environment are central to self-regulating thermal and lighting systems, sensors, and self-propelled locomotion. Since an adaptive change requires energy input, an ideal strategy would be to design materials that harvest energy directly from the changing condition itself and use it to drive an appropriate response. Based on this concept, we have developed a class of bio-inspired, hybrid architectures that are designed at the micro/nanoscale to confer a wide range of optical, wetting, adhesive, anti-fouling, and heat control behaviors at the macroscale, by harvesting chemical, mechanical, humidity, temperature, light, biochemical, and other environmental conditions. Using both experimental and modeling approaches as well as new fabrication methods, we are developing our ability to take full advantage of the immense potential for energy coupling within these hybrids to create a generation of sustainable, self-reporting, self-adapting building materials.

A simple yet scalable strategy for fabricating dry adhesives with mushroom-shaped micropillars is achieved by a combination of the roll-to-roll process and modulated UVcurable elastic poly(urethane acrylate) (e-PUA) resin. The e-PUA combines the major benefits of commercial PUA and poly(dimethylsiloxane) (PDMS). It not only can be cured within a few seconds like commercial PUA but also possesses good mechanical properties comparable to those of PDMS. A roll-type fabrication system equipped with a rollable mold and a UV exposure unit is also developed for the continuous process. By integrating the roll-to-roll process with the e-PUA, dry adhesives with spatulate tips in the form of a thin flexible film can be generated in a highly continuous and scalable manner. The fabricated dry adhesives with mushroom-shaped microstructures exhibit a strong pull-off strength of up to sim;38.7 N cm^-2 on the glass surface as well as high durability without any noticeable degradation. Furthermore, an automated substrate transportation system equipped with the dry adhesives can transport a 300 mm Si wafer over 10 000 repeating cycles with high accuracy.

Origami-inspired self-folding approach is the most durable approach to realize three dimensional (3D) micro/nanoscale polyhedral structures. In this approach, 2D lithographically patterning planar features are connected with a hinge at the joints that fold up the structure when it is heated at melting temperature. The process offers not only easy control of size and shape which actually allows for fabrication of free standing materials when the structures are made in 3D environment, but also can allow to define 3D patterning on each face of the 3D structure. In addition, if the structure is made with heterogeneous integration with diverse materials, it may result in more diverse application in electronic circuits as well as optical and biomedical modules. However, one of the challenge on the process is the spatial stress distribution on the materials, which can create cracking or delamination during the self-folding. In order to overcome this difficulty, we introduce a new sandwich type structure, which reduces the stresses on the thin film. As a result, our approach allows for fabrication of 3D polyhedral (cubic) micro structures with 3D electrical circuits defined on the 3D micro structures. Overall size of the 3D cubic structure is 200 to 1000 micrometers. Such novel strategy, even, is further applied to building 3D graphene based structure including single layer chemical vapor deposition (CVD) grown graphene sheet, and multilayer graphene oxide (GO) and reduced graphene oxide (RGO) sheets with metal pattern on them. There is no doubt that the 3D heterogeneous integrated structures will be harnessed in developing a new class of biomedical, electronic, and optic devices.

Various types of amine-modified porous silica materials have been extensively used as adsorbents by its high specific surface area. Especially, preparation of hierarchical silica materials has been researched because hierarchical structures can enlarge the specific surface area and improve the mass transfer rate. However, existing fabrication for the synthesis of hierarchically porous structures are quite complicated techniques because the processes need to additional adhesive materials, hydrothermal treatment, or high pressure in autoclave.
In this study, without the complex processes, a facile strategy for the synthesis of hierarchically porous amine-modified silica (HPAS) for desired size and shape is successfully developed. At first, hierarchically porous silica was synthesized by the process of evaporation-induced coating and self-assembly of pre-hydrolyzed tetraethyl orthosilicate (TEOS) on the pluronic P123 triblock copolymer and the surface of macroporous polyurethane foam template. Then, HPAS was manufactured by gas-phase procedure of (3-aminopropyl) trimethoxysilane (APTMS) on the surface of hierarchically porous silica. In the HPAS structure, mesopores can offer a wide surface area and many activated sites, whereas macropores and framework formed by polyurethane template can provide a structural stability and reduce a pressure drop caused by packing of nanoparticles. It is remarkable that the HPAS could be synthesized for desired shape and size from nano- to architectural scale by controlling the size and shape of polyurethane template. Thus, this facile strategy for the synthesis of HPAS could be significantly enhanced the scalability of porous silica materials.
FT-IR was used to confirm the synthesis of HPAS and negative ToF-SIMS was carried out to analyze the surface of HPAS. Nitrogen amount of HPAS was obtained by elemental analyzer, morphologies and pores were measured by FEG-SEM and TEM. BET and BJH methods were performed to confirm the specific surface area and to calculate the distributions of pore sizes of HPAS.
We focused our efforts on development of a facile strategy for manufacturing of HPAS for the desired size and shape. As a result of application of HPAS to CO₂ adsorbent, it is noteworthy that the adsorbed CO₂ amount of HPAS was 1.5 times higher, whereas the pressure drop of HPAS was 36 times lower than those of the packed amine-modified silica particles.

Spontaneous symmetry breaking is an important concept in describing many physical patterns. Spontaneous symmetry breaking is relevant in describing crumpled paper[1], the formation of ridges in indented shells, the morphogenesis of biological structures, among many other phenomena. Earlier studies on ridge formation in indented shell structures by Mahadevan et. and Nasto. Et. al [2][3] implicated the importance of local geometry and indenter effects. We have observed symmetry breaking in the deformation of macroscopic elastic shells that cannot be entirely explained by local indenter shell interactions or local geometry effects. Instead, we observe deformation behaviour that is determined by geometrical features far from the point of indentation and independent of the tip. Our study presents provisional but compelling and repeatable results from experiments and finite element analysis.
[1] A. J. Wood, “Witten &’ s lectures on crumpling,” Physica A, vol. 313, pp. 83-109, 2002.
[2] A. Vaziri and L. Mahadevan, “Localized and extended deformations of elastic shells.,” Proc. Natl. Acad. Sci. U. S. A., vol. 105, no. 23, pp. 7913-8, Jun. 2008.
[3] A. Nasto, A. Ajdari, A. Lazarus, A. Vaziri, and P. M. Reis, “Localization of deformation in thin shells under indentation,” Soft Matter, vol. 9, no. 29, p. 6796, 2013.

Advances in the conception of materiality and the technologies of materialization have always been a catalyst for design innovation in architecture. Today, technological innovation across multiple disciplines suggests that design computation is no longer limited to the binary realm of the digital, but instead becomes an intense interface to the more complex domain of the physical. Thus a new understanding of the material in architecture is beginning to arise, forging new alliances between the fields of design, engineering and natural sciences, and leading to novel multidisciplinary design approaches in architecture.
In this lecture Achim Menges will present how materiality no longer remains a fixed property and passive receptor of form, but instead, how it can be transformed into an active generator of design and an adaptive agent of both structural performance and architectural performativity. Based on an understanding of material systems not as derivatives of standardized building systems and elements but rather as generative drivers in the architectural design process, this approach seeks to develop and employ computational techniques and robotic fabrication technologies to unfold innate material capacity and specific material gestalt. Informed by research on biological systems, the concept of material systems is extended by embedding their behavioral characteristics, manufacturing constraints and assembly logics within integrative computational processes. This enables an understanding of the design of form, material and structure not as separate elements, but rather as complex interrelations in performative architectural morphology. The related research will be explained along a series of constructed prototypes and demonstrator buildings.

University of Colorado Boulder&’s College of Engineering and Applied Science National Science Foundation (NSF), Emerging Frontiers in Research and Innovation (EFRI) project is developing a "Living Wall" concept that follows the principles of biomimicry of the body's thermo-regulation systems. The exterior wall assembly responds to the environment by collecting, transferring, storing and distributing heat to regulate the interior building temperature through a metabolic process. This paper focuses on the Living Wall assembly's design performance for commercial and residential buildings. The wall assemblies can be incorporated into a building to meet all heating, cooling and ventilation needs for zero net energy approaches.
The commercial Living Wall focuses solar heat generated within exterior interstitial walls (IS Walls), collected by heat exchanging translucent inner panels embedded with biomimic hydrogels, resulting in significant buoyancy and upward air movement within the IS Walls while maintaining visible light transmittance for daylighting. The design approach uses outside air and ground coupling for space cooling, delivered to the building by buoyancy-driven airflow drawn up through an exterior cavity in the IS Wall. Solar heat collected within the wall from solar radiation provideds most space and water heating building requirements plus driving the airflow used for space cooling and heating. Solar heat stored during the day is collected and redistributed, seeding buoyant air movement when radiation is not available in the building through a network of hydrogel and micro vascular fluid channels within the Living Wall assembly. A translucent phase change material augments heat storage to mitigate temperature fluctuations. Cooling accomplished by direct ground coupled heat exchangers supply steady state temperatures distributed by the negative pressure generated by the evacuating IS Wall assemblies.
For residential buildings the Living Wall design is adapted to a more balanced space heating and cooling load profile, with more significant heating needs. The airflow cavity has smaller dimensions to meet lower airflow requirements with greater focus on heat and cooling temperature storage for heating, cooling and ventilation needs.
Utilizing detailed energy modeling with eQuest, Energy + and DOE 2 programs based on reference models developed by NREL, we found that solar heat collected in IS Wall assemblies that mimic hydrogel composite Living Wall assemblies, coupled with buoyancy-driven airflow provides adequate heat and airflow to meet heating, cooling and ventilation requirements in buildings located in the Southwestern part of the US for most occupied building hours of the year.
Keywords: Living Wall, interstitial wall, airflow cavity, Zero Net Energy (ZNE), bio-mimicry, commercial, residential, buoyancy

In this paper the authors present new developments into autonomously responsive architectural systems that adapt to environmental changes using hygroscopic material properties. The presented work expands upon previously developed research by the authors on meteorosensitive architectural systems based on the biomimetic transfer of the hygroscopic actuation of plant cones. The previously conducted research provided substantial insight into the parameters, variables and syntactic elements that enabled such meteorosentive architectural systems to be possible using the hygroscopic qualities of wooden veneer within a weather responsive composite system. The current work to be presented here further expands the research field into such autonomous responsive systems by enabling a more complex gradient of functional differentiation within a responsive element while also enabling on-surface complex articulations due to multi-directional anisotropic conditions. The new proposed system maintains the ability to operate and respond autonomously and passively, similarly to the wood veneer composite system, by embedding some of the same functional principles within the material itself. However, unlike previous form definition fabrications techniques that used veneer composite systems, the current numerically controlled fabrication methodology presented, enabled through 3D printing, looks at material syntax as a strategy for functional programming and both formal and functional differentiation. That is, the system can transition withing a single composite unit from a support structure to a responsive actuation element variably and multi-directionally. The proof-of-concept functional prototypes presented will situate the functional range of this research.

Among a range of chemical processes, biological structures born of natural evolution define and tune ranges of material properties through the orientation and varied densification of fibers within a protein matrix generating differentiation, materially and geometrically, as a continuous medium. Viewed as pliable structures, the fiber orientation in natural systems serves as the critical parameter for tuning ranges of elastic deformation. This factor offers a critical comparison to architectural systems which conventionally rely upon rigid elements interconnected with hinges to provide means of geometric transformation. Fiber-reinforced composites, on the other hand, offer means for implementing concepts of elastically deformable natural systems as manufactured morphable material systems. While the primary concern for composites in architecture is its plastic nature designable for complex geometries, the ability to prescribe the fiber structure of the composite preform presents means for manufacturing materials of both a seamless and differentially deformable nature. This research explores the formation of textiles and reinforced composites through the use of advanced CNC machine knitting technology in generating a range of pre-stressed structural systems, oriented towards defining spatial, tactile and elastic material qualities. The material systems developed in this research vary greatly in scale, but explore conditions of patterning, surface texture and bi-stability, through a structural logic termed textile hybrid. Such a logic integrates pre-stressed (form-active) textiles with elastically bent (bending-active) fiber-reinforced composites, realizing form at the equilibrium of these structural actions.
This research explores, in depth, the fibrous nature of both system components through textile structures manufactured with CNC machine knitting technology, developed along a trajectory of (i) discretized systems, (ii) seamlessly integrated fiber-reinforced composite systems, and (iii) yarn-stiffened semi-rigid systems. Initial research explores the capacity of a knitted textile to tailor and direct forces when implemented as a tensile
surface, within a boundary defined by bending-active glass-fiber reinforced polymer (GFRP) rods. Integrating diverse yarn qualities from elastic to structural, seamless materials are formed which internally house the textile hybrid behavior through the intermixing of pre-stressed regions and locally resin-impregnated areas within the continuous textile. Expanding the fiber diversity within a seamless textile, nylon monofilaments are integrated to define semi-rigid qualities without the need for resin-impregnation. This research involves collaboration with diverse knowledge sets from machine knitting defined primary by textile production for fashion, material science and aerospace engineering in defining the (diverse) performative nature of fiber-reinforced composites, and also interaction design in morphability as both a mechanism for passive adaptation as well as an actively manipulable and tactile interface.

There is a disciplinary convergence upon us, one that spans from the nano-scale to the human-scale. We are now able to program nearly every material from bits to DNA, proteins, proto-cells, smart materials, even products and infrastructure. There is a growing demand to translate these capabilities into solutions for large-scale applications rather than purely small-scale technologies At the Self-Assembly Lab, we aim towards the built-environment, from manufacturing, construction, infrastructure and products to develop more adaptive and highly resilient systems. We have demonstrated that self-assembly is scale-independent and have produced prototypes transforming from 1D, 2D to 3D and even 4D Printing aimed at inventing a future of programmable built environments.

Transient materialization explores the relationship between digital and material-based fabrications in architecture. The notion of transient materialization proposes immaterial architecture as a trigger for investigating a new possibility and cognition of morphology in architecture through space and time. In addition, the definition of immaterial architecture does not dichotomize architecture as either material or immaterial; rather, the emphasis is on invention of an ephemeral and adaptive form generated due to the specific characteristics of matter, information, environment, and time. Thus, in order to accept the challenge of this novel design in digital fabrication, this process involves experimenting with the physical and chemical properties of materials in combination with digital tools and machines. In other words, the architectural form is not anymore considered as static, but transformable. Its complexity is developed by contexts composed of materials' properties, machines' capacities, data, and corresponding conditions of space and time.
This project is inspired by the beauty of nature, the spheric membrane embodied by the soap bubble: a thin film of soapy water that usually has a lifespan of only a few seconds. In loosing the spheric geometry, it forms a foam based on n-hedron structures joined together. Through understanding the properties of soap foam bubbles, small machines, called foamS, are invented to generate moving, transient, and ever-changing three-dimensional foam by integrating detergent, gas, machines and digital information. In other words, unlike the general 3D printer machine which layers the material from the bottom up by moving the extruder, this machine is a reversed 3D printer which digitally fills the detergent with the mixture of air and helium in order to produce a growing and successive three-dimensional foam. Furthermore, the appearance of foam is sculptured by the customized mechanism on the top of machine while the foam grows upward. The additional chemical substances, thickener and humectant, are added for strengthening the foam structure and decreasing the evaporation of soapy water. The shape is not only constructed through transformative processes that are mechanically controlled and digitally informed, but also influenced by environmental conditions, such as humidity, temperature and material ability. The potential of the material, combined with environmental conditions, determines the existential path of the shape: from its transformation to its disappearance.
In summary, this research is based on the usage of soap foam bubbles, a common material in daily life, expanding its meaning, questioning its materiality through the novel experiment of digital fabrication. The aim of the project is in taking architecture beyond the creation of static forms to the design of dynamic, transformable, and ephemeral material experimental processes.

Hierarchical assembly of diblock copolymer micelles was successfully crafted into parallel stripes by flow enabled self-assembly (FESA). The micelles were precisely and programmably patterned at desired positions on a silicon substrate. Remarkably, a minimum spacing between two adjacent stripes was observed and a model was, for the first time, proposed to understand the relationship between the width of stripe and the minimum spacing between two adjacent stripes. Moreover, arrays and networks of inorganic nanoparticle were also produced by FESA of diblock copolymer/precursor solution, followed by selective removal of the diblock copolymer template. Such flow enabled self-assembly of diblock copolymer micelles is facile to implement, offering opportunities to create hierarchical structures and materials for potential applications in nanoelectronics.

High strength and low weight are essential to materials used in bridges, skyscrapers, and other structures in which a heavy penalty is paid for supporting additional mass. Introducing porosity to a monolithic material to reduce its weight has always led to a concomitant reduction in strength because less material is available to support the applied load. Here, we fabricate and mechanically test 3D copper lattices made up of micron-sized beams connected at solid nodes in the octet geometry that have higher strength than the parent copper material.
These architected cellular meta-materials were fabricated by a three step process: (1) direct laser writing of the lattice pattern into a polymer template using 2-photon lithography, (2) electroplating of Cu into the template, and (3) removal of the polymer matrix. Meso-lattices span relative densities of 0.4 to 0.8 and unit cell sizes of 6 and 8 mu;m. Uniaxial compression experiments revealed that open-cell Cu meso-lattice yield strength can exceed the yield strength of monolithic bulk Cu. We found that 6 mu;m unit cell meso-lattices with a relative density of 0.8 had a strength of 332 MPa, which surpassed the bulk yield strength by 80%. Furthermore, meso-lattice strength does not scale linearly with relative density, as predicted for the octet structure using theory from structural mechanics.
We postulate that the Cu meso-lattices are able to supersede the bulk-level strength of Cu because of the “smaller is stronger” size effect, in which single crystalline metals with micro and nano scale dimensions have increasing strength with decreasing sample size. This size effect is manifested in the meso-lattices because cross-sections of lattice beams mostly consist of a single grain so that lattice beams behave like a single crystalline metal with micron-scale dimensions. Additional evidence for the size effect is that meso-lattices with 6 mu;m unit cells have higher strengths than those with 8 mu;m unit cells at the same relative density because lattices with smaller unit cells have smaller, and stronger, lattice beams. This work demonstrates the use of size-dependent strengthening unique to nanostructures in the creation of simultaneously strong and lightweight architected materials.

We report a class of stimuli-responsive expanding polymer composites consisting of material interaction at three different length scales that enables the ability to unidirectionally transform their physical dimensions, elastic modulus, density, and electrical resistance. Such materials could be usefukl as programmable matter for achiving changes in density, mechanical properties, electrical and optical properties while achieving large dimensional changes. Carbon nanotubes and core-shell acrylic microspheres were dispersed in polydimethylsiloxane, resulting in composites that exhibit a binary set of material properties with material interactions at different length scales. Upon thermal stimuli, the liquid cores encapsulated within the microspheres vaporize, expanding the surrounding shells and stretching the matrix. The microsphere expansion resulted in visible dimensional changes, regions of reduced polymeric chain mobility, nanotube tensioning to keep microspehers in position, and overall elastic to plastic-like transformation of the composite. Here, we show composite transformations including macroscopic volume expansion (>500%), density reduction (>80%), and elastic modulus increase (>675%). Nanotubes are also used as photo-thermal heaters to heat the micro-spheres inside the composite and achieve large transformations, conductive nanotubes allow for remote expansion monitoring and exhibit distinct loading-dependent electrical responses eabling flexible skins that can conduct or insulae upon expansion. With the ability to pattern regions of tailorable expansion, strength, and electrical resistance into a single polymer skin, these composites present opportunities as structural and electrical building blocks in smart systems.