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Beyond 3-D: ‘4-D Printing’ Makes Items That Change Shape

Using a new technique known as 4-D printing, researchers can print out dynamic 3-D structures capable of changing their shapes over time.

Such 4-D-printed items could one day be used in everything from medical implants to home appliances, scientists added.

Today's 3-D printing creates items from a wide variety of materials — plastic, ceramic, glass, metal, and even more unusual ingredients such as chocolate and living cells. The machines work by setting down layers of material just like ordinary printers lay down ink, except 3-D printers can also deposit flat layers on top of each other to build 3-D objects.

"Today, this technology can be found not just in industry, but [also] in households for less than $1,000," said lead study author Dan Raviv, a mathematician at MIT. "Knowing you can print almost anything, not just 2-D paper, opens a window to unlimited opportunities, where toys, household appliances and tools can be ordered online and manufactured in our living rooms."

Now, in a further step, Raviv and his colleagues are developing 4-D printing, which involves 3-D printing items that are designed to change shape after they are printed. [The 10 Weirdest Things Created By 3D Printing]

"The most exciting part is the numerous applications that can emerge from this work," Raviv told Live Science. "This is not just a cool project or an interesting solution, but something that can change the lives of many."

3-D Printing Technology Helps Save Young Boy's Life 3:31

In a report published online Friday (Dec. 18) in the journal Scientific Reports, the researchers explain how they printed 3-D structures using two materials with different properties. One material was a stiff plastic, and stayed rigid, while the other was water absorbent, and could double in volume when submerged in water. The precise formula of this water-absorbent material, developed by 3-D-printing company Stratasys in Eden Prairie, Minnesota, remains a secret.

The researchers printed up a square grid, measuring about 15 inches (38 centimeters) on each side. When they placed the grid in water, they found that the water-absorbent material could act like joints that stretch and fold, producing a broad range of shapes with complex geometries. For example, the researchers created a 3-D-printed shape that resembled the initials "MIT" that could transform into another shape resembling the initials "SAL."

"In the future, we imagine a wide range of applications," Raviv said. These could include appliances that can adapt to heat and improve functionality or comfort, childcare products that can react to humidity or temperature, and clothing and footwear that will perform better by sensing the environment, he said.

— Charles Q. Choi, Live Science

This is a condensed version of a report from Live Science. Read the full report. Follow us @livescience, Facebook & Google+.

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