Materials

Shapeshifting Method Uses Heat to Bring 3D Printing Into the Fourth Dimension

With 4D printing, the element of time becomes part of the printing system, resulting in materials that emerge with one shape but then morph into another.

An object created by a team of researchers from Georgia Institute of Technology and two other institutions is suspended in water after permanently morphing from a flat to a curved shape in response to hot water. | Rob Felt
An object created by a team of researchers from Georgia Institute of Technology and two other institutions is suspended in water after permanently morphing from a flat to a curved shape in response to hot water. | Rob Felt

Good news this week for fans of materials that can metamorphose: Scientists have developed a new technology that produces shapeshifting objects straight from the fourth dimension.

It's a little less dramatic than it sounds, but the technology is still pretty wild.

A multinational research team from the US, China, and Singapore has developed a new process for printing out objects and tools that change shape when heat is applied to the material. The new technique falls into the category of 4D printing, which refers to materials that are printed out in one configuration but wind up in another. The research was published today in the journal Science Advances.

The term 4D printing may sound gimmicky, but it designates a particular approach to 3D printing. In physics, one way to look at the fourth dimension is to regard it as time itself. Any object in space-time has four dimensions: length, width, depth, and duration. With 4D printing, the element of time becomes part of the printing system, resulting in materials that emerge from the printer with one shape but eventually morph into another.

“4D printing means that the shape of the printed part can change as a function of time,” said lead researcher Jerry Qi, professor of mechanical engineering at Georgia Tech. “Time is part of shape-forming process. As demonstrated in this work, the printed part can change its shape dramatically upon heating.”

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The new 4D printing method ventures boldly into the fourth dimension by using materials called shape memory polymers (SMPs), Qi said. Designed with advanced computer programs, SMPs use two or more component substances, each of which has different temperature properties.

For instance, a hinge between two panels can be printed with internal stress that's only released when the hinge material is warmed up. The SMPs essentially “remember” various shapes, depending on how and where the built-in stress elements are printed. Add heat, and the hinge swings the panels into a specific configuration as the object assembles itself.

A lattice created by a multi-material 3D printer at Georgia Institute of Technology that can permanently expand to eight times its original width after exposure to heat. | Rob Felt

The new technique can also be modified down the line to employ triggering factors other than heat, Qi noted.

“Heating is just one way to stimulate the shape change, but as more materials are available, one could trigger shape change by electricity or light,” he explained.

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While the print-and-heat approach isn't entirely new, Qi’s process has several technical advantages over previous SMP designs. Printed materials can be transformed into multiple shapes by manually manipulating the material as it cools. To revert to the original shape, you just warm it up again. The approach can achieve printing and material savings up to 90 percent for manufacturers, according to the research team, while eliminating time-consuming mechanical programming.

As to future consumer applications of the technology, the sky's the limit.

“Self-assembling furniture, biomedical devices, soft robots — all are potential future applications,” Qi said. “For example, the printed part can be used as a platform for electronics devices. Installing electronics is easy when you operate on a flat platform. After installation, we heat the structure, and it transform into a three-dimensional shape.”

Think it all through to far-future scenarios, and 4D printing gets awfully close to science fiction concepts like Star Trek's famous replicators. Need a new mobile phone? Just print out a flat template and toss it in the microwave. Expecting a crowd? Just print and warm up a new sectional couch.

The future is going to be fun.

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