A team at North Carolina State University has engineered a polymer “Chinese lantern,” a ribbon-based meta-unit that can snap into over 13 distinct curved, three-dimensional shapes. The transformations occur when the structure is compressed, twisted, or both, and transitions can also be triggered remotely via a magnetic field.
The design starts from a flat polymer sheet cut into a parallelogram, with a row of parallel slits through its center to create ribbons. The top and bottom edges remain intact, and by connecting the ends, the sheet pops into a three-dimensional lantern shape. That lantern form is bistable; it has two stable states under certain deformations. Pressing down past a threshold causes it to snap into a second shape (like a spinning top); releasing returns it to the lantern state.
What’s novel is how the researchers expanded that simple two-state behavior into many shapes. By twisting the structure, folding parts of the top or bottom strips, or combining twist and compression, the lantern unit can settle into different stable morphologies. Some variants even have four stable states.
To enable remote actuation, a thin magnetic film was added to one strip of the lantern, letting an external magnetic field compress or twist it without touching. The team demonstrated prototype applications: a soft gripper (able to grasp fish), a flow-control filter that opens or closes, and a collapsed tube that can rapidly expand.
They also built a mathematical model to predict which angles and deformations yield which shapes, and how much elastic energy is stored or released in transitions. That makes it possible to design lantern units with target morphing pathways, stability, and energy output.
Looking ahead, the researchers hope to assemble many of these lantern units into larger 2D or 3D architectures, shape-morphing metamaterials and robotics components that reconfigure on demand.