快猫短视频

[video_player id=鈥�3AqsQsIw鈥� access_level=鈥漞veryone鈥漖

It鈥檚 like origami, but hands-free. Magnetic microparticles can be mixed into rubber to make 3D printed shapes that fold, morph, and move in the presence of a magnetic field.

Xuanhe Zhao at the Massachusetts Institute of Technology and his colleagues made these shapes using silicone rubber infused with magnetic microparticles.

They modified the nozzle of a 3D printer by surrounding it with coils of wire that act as an electromagnet. When the rubber is extruded, the microparticles become magnetically aligned along the direction of the magnetic field from the wire. The team could also change the orientation of the microparticles鈥� magnetisation by switching the direction of the field.

Once magnetised in a particular direction, the microparticles can be forced to move simply by applying another magnetic field. Even waving a fairly small magnet near the printed shape can cause it to fold up.

When to fold 鈥榚m

Zhao and his team printed a variety of flat and 3D shapes with magnetised microparticles embedded in various patterns. The test shapes were all just a few centimetres across, but Zhao says that it would be simple to print objects with sizes ranging anywhere from a few micrometres to several metres.

They made a flat panel that folds into a zig-zagging accordion pattern, flat snowflakes that scrunch into 3D ones, and pyramids made of stacked cubes that can be stretched and squashed along different directions.

All of these shape changes happen in under a second, and revert as soon as the magnetic field is removed. Manipulating the field can make the shapes crawl, roll, and even jump, and they can be made into bendy electronic devices or robots by adding circuitry or other components.

The researchers tested several of these abilities using a shape with six radial arms. They threw a small ball at it, and it was able to quickly fold up to catch the ball like a baseball glove. They also placed a pill at the centre of the shape and used a magnetic field to make it wrap around the pill and roll across a surface.

鈥淭he applications can be quite broad,鈥� says Zhao. 鈥淔or example, we are cleaning fouling in pipes and confined chambers with the magnetic robots now.鈥� In the future, he says, they may have medical applications like assisting minimally invasive surgeries, steering catheters in blood vessels, or applying pressure to muscles and tissues, all mediated by magnetic fields that travel right through the human body without damaging anything.