Metamaterials are synthetic materials that do not exist naturally. Their parts behave like atoms found in traditional materials, yet they possess unique optical, electrical, and magnetic characteristics. The interactions between these parts are essential for the effectiveness of a metamaterial. In the past, a component was limited to interacting only with its immediate surroundings. However, researchers have now created a mechanical metamaterial that allows these interactions to occur over greater distances within the material. This new material has potential applications in force measurement and structural monitoring.
Metamaterials are synthetic materials that do not exist in nature. Their parts behave similarly to atoms in regular materials but have unique optical, electrical, and magnetic characteristics. The interaction among these parts is vital for the functioning of a metamaterial. Previously, a component could interact mainly with its closest neighbors. Researchers at the Karlsruhe Institute of Technology (KIT) have engineered a mechanical metamaterial that enables interactions even at larger distances within the material. This innovation holds promise for applications in force measurement and structural oversight.
The research team led by Professor Martin Wegener at KIT’s Institute of Applied Physics (APH) has addressed a significant limitation in the field of metamaterials. Dr. Yi Chen, the lead author, draws parallels to human communication using the example of the “telephone game”: when a message is passed through several people, the end result may differ greatly from a direct conversation between the first and last person. Chen explains that this analogy applies to metamaterials as well. “The material we’ve developed features special structures (highlighted in red in the illustration). These structures allow components to ‘communicate’ not just with their neighboring components, but also directly with all other components throughout the material,” Chen stated.
Experiments on 3D-printed Microscopic Samples
“These structures give the material intriguing properties, such as unconventional stretching behaviors,” noted co-author Ke Wang, also from APH. The research team demonstrated this using microscopic samples of the material, produced through 3D laser printing and analyzed with a microscope equipped with a camera. Their findings revealed that when a one-dimensional (1D) beam was pulled from one end, it stretched irregularly.
Unlike a rubber band, which stretches uniformly, this metamaterial showed areas of compression while certain shorter segments stretched more than longer ones, despite the same force being applied. “This unusual behavior of local stretching and compression cannot be observed in conventional materials,” remarked Jonathan Schneider of APH, another co-author. “Our next step is to explore this behavior in both two-dimensional (planar) and three-dimensional structures.”
This metamaterial demonstrates high sensitivity to forces, which could be a significant advantage. Depending on where the force is applied within the material, varied stretching responses can occur even at relatively far-off positions. According to the team, conventional materials exhibit responses only at the exact point of force application, showing minimal or negligible effects at distant locations. A material with this degree of sensitivity could be extremely useful for engineering tasks, such as monitoring structural changes in buildings, and in biological research for assessing forces within cells.
This research received backing from KIT’s 3D Matter Made to Order (3DMM2O) Cluster of Excellence as well as Heidelberg University.
