Over the past 20 years, scientists have been developing metamaterials, or materials that do not occur naturally and have mechanical properties due to their designed structure rather than their chemical composition. They allow researchers to create products with specific features and shapes. Metamaterials are not yet widely used in everyday things, but that may soon change. Tian Chen, a postdoc at two EPFL laboratories – the flexible structures laboratory, led by Pedro Reis, and the geometric computing laboratory, led by Mark Pauly – have taken metamaterials a step further forward, developing one whose mechanical properties can be reprogrammed after a material is made. His research appears in Nature.
One material with several mechanical duties
“I was wondering if there was a way to change the geometry of a material’s structure after it was created,” Chen says. “The idea was to develop a single material that can exhibit a number of physical properties, such as stiffness and strength, so that materials do not have to be replaced every time. For example, when you twist your ankle, you first need to have a stiff splint to hold the ankle in place.Then as it heals, you can change to a more flexible one.Today you need to remove the entire splint. replaced, but the hope is that one day, one product can serve both functions. “
Silicon and magnetic powder
Chen metamaterial is made of silicon and magnetic powder and has a complex structure that allows to change mechanical properties. Every cell in the structure acts as an electrical switch. “You can activate and deactivate individual cells by applying a magnetic field. That changes the internal state of the metamaterial, and therefore its mechanical properties,” Chen says. It states that its programmed material is similar to computer devices such as hard drives. These tools contain pieces of data that can be written to and read from them in real time. The cells in its programmed metamaterial, called m-bits, act as the pieces in solid form – they can be turned on, making the material harder, on or off, making it more flexible . And researchers can toggle on and off a number of combinations to provide the mechanical properties they need at any given time.
To develop his material, Chen drew on methods from both computer science and mechanical engineering. “That’s what makes his project so special,” says Pauly. Chen also spent a lot of time testing his stuff in each of his different states. He found that it could in fact be programmed to achieve varying degrees of stiffness, deformation and strength.
Lots of research perspective
Programmed metamaterials are similar to devices, such as robots, that use complex, energy-intensive electronic devices. With his research, Chen aims to find the right balance between static materials and devices. Reis sees a lot of potential for further research using Chen’s technology. “We could devise a way to create 3D structures, because what we’ve done so far is only in 2D,” Reis says. “Or we could reduce the scale to even metamaterials do less. “Chen ‘s discovery marks a fundamental step forward, as this is the first time that scientists have developed a reproducible mechanical metamaterial. It opens up many exciting avenues for advanced research and industrial applications.
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