A study published this week in the journal Nature saw MIT engineers collaborate with the New Jersey Institute of Technology to create 3D-printed structures that can be manipulated by magnets to transform into a variety of shapes. The new technology has potential applications in the fabrication of remotely controlled biomedical devices.

Biomedical applications

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

Current work in soft robotics has not yet produced a model that is suitable for the human body or other sensitive enclosed and confined spaces. This magnetically controlled option would be safe, as it is body-benign, and efficient, as the structure's fast responsive speed would enable it to perform its assigned tasks quickly.

The novel structures were engineered using a new type of 3D-printable ink that the researchers infused with magnetic particles. This process created a device that can not only shift into complex formations according to magnetic stimuli, it can even effectively move around.

The formations that the structure can take include "a smooth ring that wrinkles up, a long tube that squeezes shut, a sheet that folds itself, and a spider-like “grabber” that can crawl, roll, jump, and snap together fast enough to catch a passing ball." The structure can even be magnetically stimulated into carrying a pill across a table by inducing it to wrap itself around the object.

The engineers also produced and tested a physical model that predicts reliably how the structures will deform and/or move. “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,” Zhao said.

Intelligent machines printed

The team further experimented with more complicated structures including an electrical ring with LED lights that could be programmed magnetically to light up either red or green. “By programming complex information of structure, domain, and magnetic field, one can even print intelligent machines such as robots," explained Zhao.

The paper is entitled "Printing ferromagnetic domains for untethered fast-transforming soft materials." The National Science Foundation, the Office of Naval Research, and the MIT Institute for Soldier Nanotechnologies supported the research.