Programmable balloons pave the way for new shape-morphing devices

Balloon shaping isn't just for kids anymore. A team of researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) has designed materials that can control and mold a balloon into pre-programmed shapes. The system uses kirigami sheets - thin sheets of material with periodic cuts - embedded into an inflatable device. As the balloon expands, the cuts in the kirigami sheet guide the growth, permitting expansion in some places and constricting it in others. The researchers were able to control the expansion not only globally to make large-scale shapes, but locally to generate small features.

The team also developed an inverse design strategy, an algorithm that finds the optimum design for the kirigami inflatable device that will mimic a target shape upon inflation.

"This work provides a new platform for shape-morphing devices that could support the design of innovative medical tools, actuators and reconfigurable structures," said Katia Bertoldi, the William and Ami Kuan Danoff Professor of Applied Mechanics at SEAS and senior author of the study.

The research is published in Advanced Materials.

An individual cut on a kirigami sheet contributes to the larger shape of the balloon like a pixel helps form an image on a 2D surface. The researchers found that by tuning the geometric parameters of these cuts, they could control and embed complex shapes.

"By only varying two parameters of the pixels, we can program all different kinds of crazy shapes into the kirigami balloons, including bends, twists and expansions," said Antonio Elia Forte, a postdoctoral fellow at SEAS and co-first author of the study. "Our strategy allows us to automatically design a morphable balloon starting from the shape that you need. It's a bottom-up approach that for the first time harnesses the elasticity of the material, not only kinematic."

Using these parameters, the researchers developed an inverse algorithm that could mix and match pixels of different width and height, or delete certain pixels altogether, to achieve the desired shape. By manipulating the parameters of individual pixels, the researchers were able to tune shapes at a significantly smaller scale. To demonstrate this, they programmed a balloon to mimic the shape of a squash (the experiments took place around Halloween) complete with the characteristic bumps and ridges along the side.

"By controlling the expansion at every level of the kirigami balloon, we can reproduce a variety of target shapes," Lishuai Jin, a graduate student at SEAS and co-first author of the paper.

The researchers also made kirigami balloons in the shapes of calabash gourds, hooks and vases, demonstrating that the approach is general enough to mimic any given shape.

Next, the researches aim to use these kirigami balloons as shape-changing actuators for soft robots. The work lays a foundation for the design of structures at multiple scales: from micro minimally-invasive surgical devices to macro structures for space exploration.

Research paper

Related Links
Harvard John A. Paulson School Of Engineering And Applied Sciences
Space Technology News - Applications and Research

Tweet

Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Monthly Supporter
$5+ Billed Monthly

paypal only

SpaceDaily Contributor
$5 Billed Once

credit card or paypal

The lightest shielding material in the world
Zurich, Switzerland (SPX) Jul 03, 2020
Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic components or the transmission of signals. High-frequency electromagnetic fields can only be shielded with conductive shells that are closed on all sides. Often thin metal sheets or metallized foils are used for this purpose. However, for many applications such a shield is too heavy or too poorly adaptable to the given geometry. The ideal solution ... read more