![]() ![]() ![]() Most modern products are treated to reduce or eliminate anisotropy (for example, plywood), but in this case the researchers sought to use the property as a responsive mechanism to encourage the material to bend in a certain direction. Anisotropy is a familiar property of cellulosic materials, like wood, that exhibit a grain and therefore behave differently in one direction than in another. The cellulose fibers within the hydrogel ink are carefully aligned, so their grain stiffness and directional swelling are directionally dependent, or anisotropic. The Harvard team developed precise swelling behaviors in strategic areas of the hydrogel structures that are similar to the tissue microstructures of flowers and plants. This approach is based on an attempt to emulate the natural microstructures in plants, particularly those that allow shape changes like thermonasty (movement in response to temperature) or mimetic polymorphism (shapeshifting to match nearby foliage-yes, plants practice biomimicry, too). Paulson School of Engineering and Applied Sciences-use a composite gel containing cellulose microfibers derived from wood, known as hydrogel-cellulose fibril ink. The researchers-hailing from the Wyss Institute for Biologically Inspired Engineering and the John A. The Harvard scientists take a third approach, which uses hydrogel printing. Dunn A sculpted surface with a complex, nonuniform curvature due to the design of the laminate architecture. Other variants, such as discs or truncated octahedrons, exhibit different geometries yet still rely on the same activated joint principle. The overall geometry can be rectilinear, as in Tibbits' self-folding strands, or planar, like his self-folding surface cubes. In this way, 4D prints are predictive structures with strategic, unidirectional hinges. Printed as a joint between two rigid sections, this component can bend when activated, with its design dictating the direction. In some cases, this component can expand up to 150 percent of its original size when activated. The two materials are arranged to create segmented structures that transform when water or another energy source is introduced to the activated component, which is usually a hydrophilic polymer. His approach centers on the fabrication of multi-material prints that are typically composed of a rigid, inert polymer, and a softer, activated component. Below, I describe three of the most promising 4D-printing methodologies developed to date, and their likely impact on the designed environment.Īs director of the Self-Assembly Lab at MIT, Tibbits has published and lectured frequently about 4D printing. ![]() ![]() As intriguing as the idea of integrating time into the 3D-printing equation may be, however, it’s important to ask whether this technology is relevant to today’s design processes and, if so, how. Their research is evidence that the still-nascent technology is moving closer, albeit slowly, to finding commercial application, with a noticeable shift in the nature of its output from frame-like, geometric constructions to fluid, organic forms. For example, a long strand of material, like plastic, can transform into a predetermined shape, such as a cube, when submerged in water or heated.įollowing Tibbits, researchers at institutions including the University of Colorado Boulder, the Singapore University of Technology and Design, and now Harvard have developed their own approaches to 4D printing. In its most basic form, the process requires the combination of a smart material and a source of energy for its activation. Four-dimensional printing is an intriguing fabrication method that has gained traction since MIT research scientist Skylar Tibbits helped to popularize the term in his 2013 TED talk. This week, researchers at Harvard University announced the development of a new, bio-inspired 4D-printing method to create objects that respond to environmental triggers much like plants. Innovators in the 3D printing space are taking on the fourth dimension, time. ![]()
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