Engineers at MIT created soft 3D printed structures the movements of which can be controlled by a magnet.

The researchers created each structures from a new type of 3D printable ink, which they infused with tiny magnetic particles. An electromagnet fitted around the nozzle of the printer made sure that the magnetic particles were swung in a single orientation as the ink was fed through the nozzle.

By controlling the magnetic orientation of individual sectors in the structure, the researchers can produce structures that can almost instantaneously shift into intricate formations and even move about in response to an external magnet.

The result is a soft actuated device that could be used for biomedical purposes. When exposed to an external magnetic field, each section of the structures move in a distinct way, depending on the direction its particles move.

With the new 3D printing platform, the researchers can print sections of a structure, and tune the orientation of magnetic particles in a certain part by changing the direction of the electromagnet on the printer’s nozzle when the part is printed.

The team also developed a model that predicts how a printed structure will deform under a magnetic field, depending on the elasticity of the printed material, the pattern of the domains in the structure and the way in which a magnet is used to orientate the magnetic particles.

The magnetic 3D printed structures 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 roll, crawl, jump and snap together fast enough to catch a passing ball. One of the structures could also be directed to wrap itself around a pill and carry it across the table.

Photos: MIT/Felice Frankel