Magnetic 3D-Printed Structures Can Crawl, Jump, Play Catch

Researchers at MIT and NJIT fabricated soft structures that can move by magnetic control and can be used for a variety of novel biomedical applications.

Innovations in biomedicine could get a significant boost from researchers working at Massachusetts Institute of Technology (MIT), who have designed soft, 3D-printed structures that can be controlled remotely by magnets. A team in MIT’s Department of Mechanical Engineering and Department of Civil and Environmental Engineering—working with scientists at the New Jersey Institute of Technology (NJIT)—created a number of these structures, including the following: a smooth ring that wrinkles up, a long tube that squeezes shut, a sheet that folds itself, and a spider-like “grabber.” The grabber can crawl, roll, jump, and snap together fast enough to catch a passing ball. Or, it can be directed to wrap itself around a small pill and carry it across a table.

The structures could be applied to the development of new magnet-controlled biomedical devices for a variety of diagnostic, surgical, and treatment functions, said Xuanhe Zhao, an MIT professor who led the research.

Crawling magnets react to magnetic fields

Researchers from MIT fabricated soft structures that can move by magnetic control from a new type of 3D-printable ink that they infused with tiny magnetic particles. (Image source: Felice Frankel for MIT)

Useful Structures

“We think in biomedicine, this technique will find promising applications,” he said in an MIT press release. “For example, we could put a structure around a blood vessel to control the pumping of blood, or use a magnet to guide a device through the GI tract to take images, extract tissue samples, clear a blockage, or deliver certain drugs to a specific location. You can design, simulate, and then just print to achieve various functions.”

Researchers used a new type of 3D-printable ink infused with tiny magnetic particles as well as a modified printer to fabricate the structures. They fitted an electromagnet around the nozzle of a 3D printer, which caused the magnetic particles to swing into a single orientation as the ink was fed through the nozzle.

The team produced structures and devices that can very quickly shift into intricate formations and even move around by controlling the magnetic orientation of individual sections in the structure, Zhao said. Various sections of the structures responding to an external magnetic field caused the movements, he said in the release. Researchers published a paper on their work in the journal Nature.

While the structures developed by the team are similar to other soft, actuated devices made from hydrogel and elastomer materials, they have the advantage of being able to quickly move and take on a different shape, researchers said. They also can move untethered, which is a boon—especially for devices designed to move inside the body.

“There is no ideal candidate for a soft robot that can perform in an enclosed space like a human body, where you’d want to carry out certain tasks untethered,” stated Yoonho Kim, an NJIT researcher who also worked on the project, in the MIT release. “That’s why we think there’s great promise in this idea of magnetic actuation, because it is fast, forceful, body-benign, and can be remotely controlled,” he said.

Key to the success of the team’s work is that they developed structures with individual magnetic “domains”—each with a distinct orientation of magnetic particles—that can move distinctly in response to a magnetic field, researchers said. In this way, the structures have the ability to engage in more complex articulations and movements than if they were controlled merely as one entire structure.

Printing

The team also developed tools for others to use to print similar structures. Scientists can use their 3D-printing platform and process to fabricate various domains of a single structure. They also can tune the orientation of magnetic particles in a particular domain by changing the direction of the electromagnet encircling the printer’s nozzle as that domain is printed, researchers said. In addition, they developed a physical model that predicts how a printed structure will deform under a magnetic field to allow for some idea of how the finished, printed object will move.

“People can design their own structures and domain patterns, validate them with the model, and print them to actuate various functions,” Zhao said. “By programming complex information of structure, domain, and magnetic field, one can even print intelligent machines, such as robots,” he added in MIT’s release.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.

 

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