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Tenth Annual Symposium on Frontiers of Engineering DESIGNER MATERIALS

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Tenth Annual Symposium on Frontiers of Engineering Introduction KRISTI S. ANSETH University of Colorado Boulder, Colorado DIANN E. BREI University of Michigan Ann Arbor, Michigan Over the past century, the materials field has evolved from the simple searching out, finding, and using of materials to the elegant, rational designing of highly functional materials, often assembled atom by atom, to impart desired and controlled properties. Materials designers have brought us smart materials, quantum wires and dots, diamond films and coatings, healing materials, and biomaterials. Past scientific breakthroughs enabled us to visualize atoms inside materials and use quantum mechanics to explain how they interact to create bulk properties. Now we are heading down a path toward understanding not only how materials work, but also how they can be synthesized, manipulated, and processed in regulated ways on a molecular and atomistic level to create materials that can respond to changes in the environment in controlled and desirable ways. For example, biomaterials have evolved from off-the-shelf materials that served as passive, inert implants to sophisticated, rationally designed chemical structures that are biologically active, can control cell interactions and functions, and, in some cases, can actively promote healing. Smart materials have progressed from the natural crystals used in sonar during World War II to structural materials tailored for vibration, noise, and shape control of complex engineered systems, such as fighter jets and space optics. Materials science involves applying a basic understanding to practical problems. Slowly but surely, materials scientists are becoming adept at using the

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Tenth Annual Symposium on Frontiers of Engineering tools of molecular genetics in the research laboratory. The only other place where materials are synthesized with such high fidelity, diversity, efficiency, and sophistication from a very limited set of building blocks is inside the cell! Materials scientists are beginning to exploit and mimic the evolved qualities of cells that enable their material production. Scientists can now readily control intracellular protein biosynthesis, which offers a general route to the engineering of macromolecular materials with precisely defined molecular weights, compositions, and sequencing. Materials scientists are also using living systems, such as the phage virus, as guides to the evolution of selected peptides that can recognize, bind, and grow electronic and magnetic building blocks. Scientist and engineers are progressively bringing together natural process and innovative human ideas to design materials at all scales that will revolutionize how we engineer our world. At the nano-/microscale, materials can now be organized to share electrons between atoms to establish synergistic connections between phenomena. In multiferroric materials, for example, electric/magnetic interaction can be magnified by the transfer of energy between magnetic, electrical, and mechanical atoms. These materials will have real applications, such as futuristic radar systems for the battlefield and powerful cell phone antennas that will always be in contact—eliminating out-of-coverage areas! Another example is microscale “dimensioning,” which can increase the surface area-to-volume ratio of components to provide rapid heat transfer. This could lead to the design of new materials, such as shape-memory alloy thin films, that can operate faster by two orders of magnitude, resulting in the highest known power densities for any solid-state actuation system. This technology could someday provide powerful micro-/mesoscale actuators for everything from new internal drug-delivery systems to systems that direct the nose cones of precision munitions. Most current active materials can respond with one, or at most two, functions. But engineers envision extending the multifunctionality prevalent on the small scale in biological materials to larger scale engineering systems. Imagine the possibilities for structural materials with power, sensing, actuation, and processing/control capabilities! Imagine morphing aircraft profiles that can fly long distances as efficiently as birds, dive and attack if necessary, and land quietly. Imagine safety structures with crush zones during impact that can then heal themselves and return to operation. Imagine louvered or pore-based “smart skins” for temperature compensation and “comfort structures” that can eliminate noise and vibrations in cars or planes. One day, perhaps soon, engineers will no longer be constrained by the properties of a material. Instead, they will define a material that fits the application requirements, thus opening the door to capabilities not yet thought of. The only limitation will be our imaginations.