A new dimension for 3D printing

3D printing of complex objects usually takes a long time because the printing process has to lay down a large number of 2D layers to build up the object. The process usually wastes much of the material needed to support the unfinished object. There are several new ways to make flat materials that fold themselves into 3D shapes, but they have drawbacks. For the first time, researchers combined 2D printing, origami, and chemistry to create a method of rapidly fabricating 3D objects without creating waste materials. These shapes can be folded on their own in seconds.

For some time, 3D printing has been used to create product prototypes and is now being used more and more in the manufacture of commercial goods, including even parts for jet engines. But every 3D fabrication method has limitations, such as the long time it takes to finish a print or the wastage of leftover materials in the print. 4D printing is a concept that aims to reduce this problem using a minimum amount of materials, chosen for their particular special properties, allowing them to fold themselves into complex 3D shapes under the right conditions. It’s called 4D printing, because the folding process itself takes time, which is often referred to as the 4th dimension. Ironically, a new method of fast 4D printing is starting in the 2D realm.

“My team and I figured out how to use accessible tools and materials to create self-folding 4D objects,” said Project Assistant Professor Koya Narumi of the Department of Electrical Engineering and Information Systems at the University of Tokyo. “Basically, we make flat sheets with origami patterns on them, and these patterns can be intricate, even taking hours for skilled origami artists to create. But thanks to our special process, you can pour hot water over these flat sheets and watch them transform into complex 3D shapes in seconds.”

This technique uses a special type of inkjet printer built to print with UV reactive materials — although the machines themselves cost tens of thousands of dollars, they are often found in community builders and repair shops alike. This printer prints 2D origami designs on both sides of a heat-shrinkable plastic sheet. The ink it uses does not shrink and remains pliable when dry. As the base sheet shrinks when heated and the ink resists shrinkage, by leaving gaps between portions of the ink on one side or the other, the designer can control which way certain sections of the sheet fold. Hot water is used to apply heat to the flat sheet so that it spontaneously folds into intricate origami constructions.

“Our biggest challenge was perfecting the options for hardware and materials, which took us more than a year to narrow down to a final choice,” said Narumi. “But all the trial and error is worth it; compared to previous research around this same basic idea, we’ve increased the output resolution by 1,200 times, which means the designs we can create aren’t just new, they can be used for real applications. In the future, we may explore functional materials, such as conductive or magnetic inks, which can be used for machines and other functional devices.”

Narumi and team hope this innovation can be used in areas such as fashion, where material wastage is often high, especially in areas where bespoke designs are in high demand. But considering the previously folded form is entirely flat, there’s also room for this to be useful in any situation where there are tight logistical or storage concerns. The printed designs can even be mailed out, and recipients can then heat them up to turn them into their ordered items. And it could even be used in the disaster recovery field, where certain items, perhaps including medical items, are needed but are often difficult to transport, and are made much easier when the items needed are basically flat.

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Journal articles: Koya Narumi*, Kazuki Koyama*, Kai Suto, Yuta Noma, Hiroki Sato, Tomohiro Tachi, Masaaki Sugimoto, Takeo Igarashi, and Yoshihiro Kawahara (*co-first author) Inkjet 4D Print: Self-folding Tessellated Origami Objects by Inkjet UV Printing. ACM Transactions on Charts. https://doi.org/10.1145/3592409

Funding:
This research is partially supported by JST ACT-I, Grant Number JPMJPR18UN; Value Exchange Engineering, a joint research project between Mercari, Inc and RIISE; and JST AdCORP, Grant Number JPMJKB2302.

Useful links:
Department of Electrical Engineering and Information Systems
https://www.eeis.tu-tokyo.ac.jp/en/

Koya Narumi
https://narumi.me/

Research contact:
Project Assistant Professor Koya Narumi
Graduate School of Engineering, University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
(email protected)

Press Contact:
Mr Rohan Mehra
Public Relations Group, University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
(email protected)

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