“Chinese Lantern” Polymer Could Revolutionize Robotics and Beyond with Shape-Shifting Abilities
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A new polymer structure, inspired by the form of a traditional Chinese lantern, is capable of rapidly transforming into over a dozen distinct three-dimensional shapes when subjected to compression or twisting. This groundbreaking development, detailed in the journal Nature Materials on October 10, offers the potential for remotely controlled, adaptable devices with applications ranging from delicate robotics to innovative underwater technology.
Researchers have engineered a material that defies conventional structural limitations, opening doors to a new era of shape-morphing materials. The ability to remotely control these transformations via a magnetic field further enhances the technology’s versatility and potential impact.
From Flat Sheet to Multifaceted Form
The creation of this remarkable material began with a simple premise: a thin polymer sheet cut into a diamond-shaped parallelogram. The team then meticulously sliced a series of evenly spaced lines through the sheet, creating parallel ribbons connected by solid strips at the top and bottom. Joining the ends of these strips naturally causes the sheet to fold into its signature lantern-like shape.
“This basic shape is, by itself, bistable,” explains a senior researcher involved in the project and a professor of mechanical and aerospace engineering at North Carolina State University. “It has two stable forms. It’s stable as a lantern, but compression causes it to snap into a spinning-top shape, storing energy that’s released when pulled back.”
Expanding the Shape-Shifting Repertoire
The team quickly discovered that the lantern’s potential extended far beyond these two initial forms. By applying a twist to the structure, or by manipulating the solid strips at the top and bottom, they were able to generate a multitude of additional shapes.
“Each of these variations is also multistable,” says a former Ph.D. student at NC State, now a postdoctoral researcher at the University of Pennsylvania. “Some can switch between two states, while one configuration exhibits four stable states depending on the applied force – compression, twisting, or a combination of both.”
Magnetic Control and Real-World Applications
To enable remote control, the researchers integrated a thin magnetic film onto the bottom strip of the lantern structure. This allows for precise manipulation – twisting or compressing the structure – using an external magnetic field.
The potential applications are vast. The team demonstrated the design’s utility as a gentle magnetic gripper capable of safely handling delicate objects like fish, a flow-control filter for underwater environments, and a device that can rapidly extend to reopen collapsed tubes.
Modeling the Mechanics of Transformation
To fully understand and predict the behavior of these “lanterns,” the research team developed a sophisticated mathematical model. This model maps the relationship between the geometry of each angle and both the final shape achieved and the amount of elastic energy stored within each stable configuration.
“This model allows us to program the desired shape, its stability, and its power when potential energy is converted to kinetic energy,” explains the postdoctoral researcher. “These are critical factors for creating shapes tailored to specific applications.”
The Future of Shape-Morphing Materials
Looking ahead, the researchers envision assembling these lantern units into more complex 2D and 3D architectures. This could pave the way for advancements in mechanical metamaterials and robotics, creating systems capable of unprecedented adaptability and functionality.
“Moving forward, these lantern units can be assembled into 2D and 3D architectures for broad applications in shape-morphing mechanical metamaterials and robotics,” states the professor at North Carolina State University. “We will be exploring that.”
The research was supported by the National Science Foundation under grants 2005374, 2369274 and 2445551. The study was co-authored by Caizhi Zhou and Haitao Qing, both Ph.D. students at NC State, and by Yinding Chi, a former Ph.D. student at NC State who is now a postdoctoral researcher at Penn.
