Materials scientists are increasingly exploring the design of dynamic materials that can change shape in response to their environment for novel applications.
Researchers at Rutgers University-New Brunswick are on-board with the development of new smart metamaterials that can dynamically transform from being stiff to soft, as well as change shape, in response to temperature.
The team led by author Howon Lee, an assistant professor in the Department of Mechanical and Aerospace Engineering, used 4D printing to create the flexible, lightweight materials, which researchers said could be used in the design of airplane or drone wings, soft robotics, and implantable biomedical devices.
|4D-printed metamaterials can be temporarily transformed into any deformed shape and then returned to their original shape on demand when heated. The scale bar is 2 millimeters. (Image source: Chen Yang/Rutgers University-New Brunswick)|
“Traditional metamaterials have fixed mechanical properties and geometry once manufactured,” Chen Yang, a doctoral student in Lee’s lab who worked on the research, explained to Design News. “Our 4D-printed metamaterials add tunability, reconfigurability, and deployability.”
4D printing is based on the 3D-printing technology to turn digital models to physical objects, but it takes the process a step further, using special materials and designs to print objects that change shape with environmental conditions.
The Rutgers team combined 3D-printing, shape-memory polymer, and existing mechanical metamaterials, Octet truss and Kelvin foam, in their research, Yang said. “The current state of 4D-printing focuses on geometrical transformation; we focused on tunable mechanical properties of our 4D-printed mechanical metamaterials,” he explained.
Using heat, the Rutgers team can tune their materials so they stay rigid when struck or become soft as a sponge to absorb shock, researchers said. The stiffness can be adjusted more than 100-fold in temperatures between room temperature (73 degrees) and 194 degrees Fahrenheit, which allows for significant control of shock absorption.
Moreover, the materials can be reshaped for a wide variety of purposes, such as temporarily transformed into any deformed shape and then returned to their original shape on demand when heated, Yang said.
“Tunable materials add adaptability to materials so that they can work in environments or situations with different requirements of mechanical properties or geometrical constraints, without needs to redesign and re-manufacturer the material,” he told us. “It also adds functionalities such as deployability to save transportation cost or to get through narrow space.” The team published a paper on their work in the journal Materials Horizons.
The materials’ adaptability make them well-suited for a range of applications, such as for airplane or drone wings that change shape to improve performance; structures that are collapsed for space launches and reformed in space for a larger structure, such as a solar panel; and soft robots that could have variable flexibility or stiffness that is tailored to the environment and task at hand, researchers said.
Next steps for the researchers include finding such applications for the metamaterials as well as seeking stimuli other than temperature to inspire their shape change, in addition to developing materials with new properties, Yang said.
Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.
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