Researchers use light to remotely control curvature of plastics

March 22, 2017 by Matt Shipman  
Researchers at North Carolina State University have developed a technique that uses light to get flat, plastic sheets to curve into shapes such as spheres, tubes or bowls. Credit: Amber Hubbard

Researchers at North Carolina State University have developed a technique that uses light to get two-dimensional (2-D) plastic sheets to curve into three-dimensional (3-D) structures, such as spheres, tubes or bowls.

The advance builds on earlier work by the same research team, which focused on self-folding 3-D structures. The key advance here is that rather than having the fold along sharp lines—into polygonal shapes such as cubes or pyramids—the plastics bend and curve.

Researchers Michael Dickey, a professor of chemical and biomolecular engineering at NC State, and Jan Genzer, the S. Frank and Doris Culberson Distinguished Professor in the same department, were early leaders in the field of self-folding 3-D structures. In their landmark 2011 paper, the researchers outlined a technique in which a conventional inkjet printer is used to print bold black lines onto a pre-strained plastic sheet. The plastic sheet was then cut into a desired pattern and placed under an infrared light, such as a heat lamp.

The printed lines absorbed more energy from the than the rest of the material, causing the plastic to heat and contract—creating a hinge that folded the sheets into 3-D shapes. By varying the width of the printed lines, or hinges, the researchers were able to change how far—and how quickly—each hinge folds. The technique is compatible with commercial printing techniques, such as screen printing, roll-to-roll printing, and inkjet printing, that are inexpensive and high-throughput but inherently 2-D.

But now they're using a similar approach to accomplish a very different result.

video demonstrating the technique

"By controlling the number of lines and the distribution of ink on the surface of the material, we can produce any number of curved shapes," says Dickey, co-corresponding author of a paper on the self-curving plastics. "All of the shapes use the same amount of ink; it's simply a matter of where the ink is applied on the plastic."

"Our work was inspired by nature, because natural shapes rarely incorporate crisp folds, instead opting for curvature," says Amber Hubbard, a Ph.D student at NC State and co-lead author of the paper. "And we found that, in order to make functional objects, we often needed to use a combination of curved and folded shapes.

"Other researchers have developed techniques for creating self-curving materials, but they did this using , such as hydrogels," Hubbard adds. "Our work is the first attempt to accomplish the same using thermoplastics—which are stronger and stiffer than the soft materials. That makes them more attractive for use in performing some practical actions, such as gripping an object."

"The materials we're working with also hold their , even after the light is removed," says Russell Mailen, a Ph.D student at NC State and co-lead author of the paper. "That's an advantage, because soft change shape only when exposed to a solvent, and once they are removed from the solvent they lose their shape."

The researchers have also developed a computational model that can be used to predict the 3-D shape that will be produced by any given printing pattern.

"One of our goals is to fine-tune this model, which Mailen developed," Genzer, co-corresponding author, states. "Ultimately, we'd like to be able to input a desired 3-D shape into the model and have it create a pattern that we can print and produce."

The paper, "Controllable curvature from planar polymer sheets in response to light," is published in the Royal Society of Chemistry journal Soft Matter and was selected by the journal to be featured on the cover.

Explore further: Researchers remotely control sequence in which 2-D sheets fold into 3-D structures

More information: Amber M. Hubbard et al, Controllable curvature from planar polymer sheets in response to light, Soft Matter (2017). DOI: 10.1039/C7SM00088J

Related Stories

Technique enables adaptable 3-D printing

January 13, 2017

Three-dimensional printing technology makes it possible to rapidly manufacture objects by depositing layer upon layer of polymers in a precisely determined pattern. Once these objects are completed, the polymers that form ...

Researchers build 3-D structures out of liquid metal

July 9, 2013

(Phys.org) —Researchers from North Carolina State University have developed three-dimensional (3-D) printing technology and techniques to create free-standing structures made of liquid metal at room temperature.

Recommended for you

Imaging technique unlocks the secrets of 17th century artists

November 21, 2017

The secrets of 17th century artists can now be revealed, thanks to 21st century signal processing. Using modern high-speed scanners and the advanced signal processing techniques, researchers at the Georgia Institute of Technology ...

Study shows how to get sprayed metal coatings to stick

November 21, 2017

When bonding two pieces of metal, either the metals must melt a bit where they meet or some molten metal must be introduced between the pieces. A solid bond then forms when the metal solidifies again. But researchers at MIT ...

Physicists design $100 handheld muon detector

November 20, 2017

At any given moment, the Earth's atmosphere is showered with high-energy cosmic rays that have been blasted from supernovae and other astrophysical phenomena far beyond the Solar System. When cosmic rays collide with the ...

A curious quirk brings organic diode lasers one step closer

November 20, 2017

Since their invention in 1962, semiconductor diode lasers have revolutionized communications and made possible information storage and retrieval in CDs, DVDs and Blu-ray devices. These diode lasers use inorganic semiconductors ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.