Is This the Strongest Origami in the World?

Remember those cartoon characters with corrugated arms that sprung out and retracted like slinkies? Well, a team of researchers has invented some zigzag origami-inspired structures that can do just that. And they could be deployed in everything from "robotics, aerospace, and architecture."

In a study published today in the journal PNAS, the researchers describe creating a multi-functional "zippered tube" configuration that is strong enough to support a considerable amount of weight, and that can be handily folded flat for ease of storage and shipping owing to its thin flexible sheets. In a nutshell, the researchers used an origami technique dubbed "Miura-ori folding" to create zigzag-folded strips of paper. They then made a tube by gluing the two strips of paper together.

"We introduce a new method of assembling origami into coupled tubes that can increase the origami stiffness by two orders of magnitude," they write in their paper. "The new assemblages can deploy through a single flexible motion, but they are substantially stiffer for any other type of bending or twisting movement."

Evgueni Filipov, study co-author and doctoral student at the University of Illinois's department of Civil and Environmental Engineering, explained that the tubes could also be coupled (stacked, in parallel) in many different ways to add stiffness to the paper structures.

"We can create many different types of structures from these, and we can arrange them in many different scales from the micro-scale to large civil engineering structures," he told me over the phone.

Origami—the art of paper folding—has been inspiring developments in everything from DNA origami to teeny weeny self-assembling micro-medical robots. For the team of researchers from the University of Illinois, Georgia Institute of Technology, and the University of Tokyo, the aim is to create a system that is compact but capable of shape-shifting into different structures with multiple functions.

"[These tubes] have a very flexible deployment mode, but they're very stiff in other modes," said Filipov. "With the idea of an extendable robotic arm, you could have it stowed away, then deploy it when you're space. It could also support a load."

Not limited to space exploration, Filipov explained that the extendable flexi-arms could also be used on cranes on construction sites. Tiny medical drug-delivery robots (at the nanometer scale) with slinky-like arms could also be an option in the future. As the zipper configuration can also work by combining tubes with different geometries and folding angles, the researchers envision that this could allow them to construct larger 3D structures such as bridges and emergency shelters in the future.

Though the researchers have succeeded in creating some paper and cardboard zigzag structures that are both rigid and flexible, according to Filipov, the biggest challenge is manufacturing and fabricating all the possible structures on different scales, and making sure that the structures are stable and reliable.