The two-dimensional shapes shown at the top of the image, made by attaching paperboard templates onto polymer substrates, fold themselves into the 3D structures shown at the bottom when heated. Image: Yong Zhu.
The two-dimensional shapes shown at the top of the image, made by attaching paperboard templates onto polymer substrates, fold themselves into the 3D structures shown at the bottom when heated. Image: Yong Zhu.

Researchers from North Carolina (NC) State University have developed a new technique for creating self-folding three-dimensional (3D) structures. Specifically, the researchers use templates to constrain deformation in certain selected areas on a two-dimensional (2D) substrate, which in turn dictates the resulting 3D structure of the material.

The new technique does not rely on cutting or printing on the material, unlike most other self-folding origami techniques. It is also different from continuous shape morphing, which is typically controlled by engineering the in-plane strain at various parts of the material. Instead, the researchers simply attach paperboard sheets with specific patterns to a polymer substrate.

"When heat is applied to the polymer, it shrinks," explains Yong Zhu, a professor of mechanical and aerospace engineering at NC State and corresponding author of a paper on the work in Advanced Functional Materials. "However, the sections of polymer that are attached to the paperboard are restrained from shrinking, causing the overall substrate to bend and curve."

By varying the pattern made by the paperboard templates, the researchers are able to create a variety of shapes, from simple cones to complex, tiered structures. The self-folding operations can be executed at temperatures as low as 120°C.

"This is a proof of concept paper, and next steps include incorporating functional electronic elements into the material, giving it potential value for manufacturing applications," says Jianxun Cui, first author of the paper and a postdoctoral researcher at Carnegie Mellon University who worked on this project while a PhD student at NC State.

This story is adapted from material from North Carolina State University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.