Scientists have created robots that can shapeshift between solid and liquid states, enabling them to perform mind-boggling feats such as jumping, climbing, and even oozing out of a cage in a way that is eerily reminiscent of the T-1000 robots of the Terminator franchise, reports a new study.
The shape and movements of the machines are controlled by magnetic fields, an approach that may lead to new biomedical and engineering technologies, such as targeted drug delivery, circuit assembly, or the creation of universal screws.
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Soft robots are typically much more malleable than their hard-bodied counterparts, but the tradeoff is that they are not as strong, fast, or easily controlled as solid machines. Now, an international team of engineers has developed a material made of gallium metal that is embedded with tiny magnetic microparticles.
This “magnetoactive phase transitional matter” (MPTM) uniquely combines the high mechanical strength, load capacity, and fast locomotion speed the solid phase with “excellent morphological adaptability (elongation, splitting, and merging) in the liquid phase,” according to a study published on Wednesday in the journal Matter.
“Folks have been working on these small-scale, magnetically responsive robots and machines for quite a while now,” said Carmel Majidi, who heads the Soft Machines Lab at Carnegie Mellon University and is senior author on the new study, in a call with Motherboard. “In parallel with that, my group has been pioneering a lot of techniques using liquid metals—metals like gallium that have a very low melting point.”
“This is one of the attempts at merging these two approaches” and “just seeing what happens when you start blending these two together,” he continued. “The hope was for a ‘best of both worlds’ scenario where we could take advantage of the high electrical conductivity and the phase-changing abilities of the gallium metal with the magnetic responsiveness of magnetic microparticle systems.”
The machines that the team built were able to respond to magnetic fields because of the magnetic microparticles in their bodies. By placing the robots inside an alternating magnetic field, Majidi and his colleagues at Sun Yat-sen University and Zhejiang University in China make them move around and even heat up, so that they liquify.
“When you have a metal that’s in the presence of an alternating magnetic field, we just know from fundamental principles of electromagnetism that that causes basically electrical current to spontaneously flow through that metal,” Majidi explained. “It’s that spontaneous electrical current that heats up the metal and causes it to melt.”
With this technique, the researchers were able to get MPTM robots to solder circuits, mold themselves into a universal screw, remove objects from a dummy stomach, and overcome obstacle courses.
They were also able to make a cute little LEGO man out of MPTM that liquefies itself and moves through the bars of a cage. Though the robot appears to self-coalesce into its original shape on the other side, Majidi clarified that it was manually recast by the team and then put back into the shot.
“It’s almost T-1000-like in the sense that you have that figurine and it melts into a blob, and it gets sucked through those jail bars,” Majidi said, adding that the villainous assassin android served as an inspiration for the robot.
The dynamic shapeshifting powers of the robots could be adapted to serve many functions, especially in biomedicine. Future iterations of MPTM machines might be able to deliver medications to specific organs, or extract dangerous objects from the body. The ability to switch between solid and liquid states could also be useful in accessing any confined or hard-to-reach spaces
“I wouldn’t have imagined that there were so many different responses and capabilities of these material systems. That really stood out as pretty surprising, and also exciting, about this material.”
