September 16, 2019 | 65° F

Researchers at Rutgers create new 'meta-materials' with 4D printing

Photo by Wikimedia |

 Despite the name, 4D printing is essentially 3D printing, except that the materials are more flexible. The process of 4D printing involves temperature, in order to tune the mechanical properties of the materials and trigger their shape changing ability. 

The pinnacle in the realm of creation just a few years ago was 3D printing. Now, researchers in the Department of Aerospace and Mechanical Engineering at Rutgers University have discovered a new frontier in 4D printing.

Chen Yang, a graduate student and researcher, said that “4D printing is 3D printing with shape transformation capability over time.” This means that this new technology, unlike the stiff plastics created though 3D printing, is able to create complex machinery. 

This innovation in printing technology was not so much due to the printer itself evolving, but the materials used for the printing itself advancing, he said. 

These new materials are known as metamaterials, which are described by Yang as “materials engineered to exhibit unusual and counter intuitive properties … The name ‘metamaterials’ is from the Greek word ‘meta,’ meaning ‘higher’ or beyond.”

The use of metamaterials will give way to machines that were physically impossible though conventional means. 

“We combine design of metamaterials, shape-memory polymer and 3D printing to create tunable metamaterials,” Yang said. “Previous metamaterials didn't have the tunability in mechanical properties and flexibility of shape transformation. But it will soon give way to new innovations that allow machines to adapt to certain situation if need be.”

Yang also said the tunable metamaterials we created can be potentially used in shock absorption mechanism, morphing airplane or drone wings and soft robotics. When using shock absorption mechanisms, for example in a car, it can tune to absorb the shock for safety and comfort. When using it in airplane wings, it can morph to optimize drag force. In soft robots, it can deform to adapt to environmental constraints.

The process in which 4D-printed technologies change shape and adapt is by tunable mechanical properties and reconfigurable shape came from constituent shape memory polymer of metamaterials, Yang said. This means that the machines created with metamaterials are programmed to certain shapes that they can switch between when needed. 

Like 3D printing, temperature is an essential part of the process of using metamaterials. Yang said the role of temperature in 4D printing is that these metamaterials were fabricated using UV-reactive polymer and 3D printing technology, projection micro-stereolithography. Temperature is the stimulus to tune mechanical properties and trigger shape-changing capability. 

Stereolithography is defined by Live Science as “one of several methods used to create 3D-printed objects. It's the process by which a uniquely designed 3D printing machine, called a stereolithography apparatus (SLA) converts liquid plastic into solid objects.”

Although 4D printing will most likely not see any commercial use anytime soon, there is great hope for the applications of this technology. 

“Metamaterials already demonstrated unprecedented properties. With tunability and reconfigurability, it can adapt to environments and tune performances based on requirements. Fields that it can potentially be used are automobiles, aeronautics, robotics and medical devices,” Yang said. 

Christian Balbuena

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