With just the wave of a magnet, MIT researchers can control soft 3D printed structures and make them complete a range of movements, such as crawling, rolling up or jumping. The engineers believe this technique could be used for “promising applications” in biomedicine.

Massachusetts Institute of Technology (MIT) engineers have developed soft, 3D printed structures using a new type of 3D printable ink which is infused with tiny magnetic particles. After printing, the structures can be controlled by waving a magnet. Imagine marionettes without the strings.

Although magnetically activated materials have been created before, the difference here is that the MIT researchers have achieved a range of complex movements. The varied structures all move in different ways.

For example, a ”spider-grabber” can crawl, roll, jump, and snap together fast enough to catch a ball, a smooth ring shape can be controlled to wrinkle up, a long tube will squeeze shut and a sheet structure will fold itself completely.

As well as being just ridiculously fun to create and control, the engineers also have bigger plans. For example, magnetically controlled biomedical devices.

Xuanhe Zhao, the Noyce Career Development Professor in MIT’s Department of Mechanical Engineering and Department of Civil and Environmental Engineering, says: “We think in biomedicine this technique will find promising applications. 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.”

Fabricating the Magnetic Structures

To develop the structures, the engineers fitted an electromagnet around the nozzle of a 3D printer. They printed the structures using the new 3D printable ink infused with tiny magnetic particles. The nozzle caused the magnetic particles in the ink to swing into a single orientation as it went through.

The magnetically activated structures are “soft actuated devices” but, unlike other such devices such as shape-memory polymers, they are quick to respond and will change shape in just minutes, instead of over hours.

Co-author, Yoonho Kim, explains: “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. 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.”

Previous attempts to create such devices relied on molds, rather than 3D printers. The printers enable the researchers to create “domains” or sections of a structure with its own orientation of magnetic particles. This is what enables complex articulations and distinct movements.

To predict how a printed structure will move, the researchers developed a model which has shown its predictions match experiments closely. Zhao explains: ”We have developed a printing platform and a predictive model for others to use. People can design their own structures and domain patterns, validate them with the model, and print them to actuate various functions.”

Find out more about the devices, their movements, and applications on the MIT News page. The researcher’s work, “Printing ferromagnetic domains for untethered fast-transforming soft materials”, was also printed in the journal Nature.

Source: Science Daily