Misc Tid Bits

Fold-able house that can fit a backpack

Fold-able house that can fit a backpack

How exciting is the idea of a fold-able house that could fit in a backpack? Isn’t it so exciting? Harvard researchers have designed a new type of fold-able material that is amazingly versatile. It can change size, volume, and shape. It’s so strong it can be folded flat to take on the weight of an elephant without breaking, and pop right back up for the next task, says a report published in the Harvard Gazette.

The research was led by Katia Bertoldi, the John L Loeb Associate Professor of the Natural Sciences at the John A. Paulson School of Engineering and Applied Sciences (SEAS); James Weaver, senior research scientist at the Wyss Institute for Biologically Inspired Engineering at Harvard University; and Chuck Hoberman of the Graduate School of Design. It is described in Nature Communications.

“We’ve designed a 3-D, thin-walled structure that can be used to make fold-able and re-programmable objects of arbitrary architecture, whose shape, volume, and stiffness can be dramatically altered and continuously tuned and controlled,” said Johannes TB Overvelde, a graduate student in Bertoldi’s lab and first author of the paper.

The structure is inspired by an origami technique called snapology, and is made from extruded cubes with 24 faces and 36 edges. Like origami, the cube can be folded along its edges to change shape. The team demonstrated, both theoretically and experimentally by a centimeter-scale prototype, that the cube can be deformed into many different shapes by folding certain edges, which act like hinges. The team embedded pneumatic actuators into the structure, which can be programmed to deform specific hinges, changing the cube’s shapes and size, and removing the need for external input. Sixty-four of these individual cells to create a 4-by-4-by-4 cube that can grow, and shrink, change its shape, change the orientation of its micro structure, and fold completely flat. As the structure changes shape, it also changes stiffness, meaning one could make a material that’s very pliable or very stiff using the same design. These actuated changes in material properties add a fourth dimension to the material.

“We do not only understand how the material deforms, but also have an actuation approach that harnesses this understanding,” said Bertoldi. “We know exactly what we need to actuate in order to get the shape we want.”

The material can be embedded with any kind of actuator, including thermal, dielectric, or even water.
“The opportunities to move all of the control systems onboard combined with new actuation systems already
being developed for similar origami-like structures really opens up the design space for these easily deploy-able transformable structures,” said Weaver.

“This structural system has fascinating implications for dynamic architecture, including portable shelters, adaptive building facades, and retractable roofs,” said Hoberman. “Whereas current approaches to these applications rely on standard mechanics, this technology offers unique advantages such as how it integrates surface and structure, its inherent simplicity of manufacture, and its ability to fold flat.”

“This research demonstrates a new class of foldable material that is also completely scalable,” Overvelde said, “It works from the nano scale to the meter-scale and could be used to make anything from surgical stents to portable pop-up domes for disaster relief.”

This paper was coauthored by Twan A. de Jong, Yanina Shevchenko, Sergio A. Becerra, and George Whitesides. The research was supported by the Materials Research Science and Engineering Centers, the National Science Foundation and the Wyss institute through the Seed Grant Program.