A miniature, shape-shifting robot can melt itself and reform, allowing it to complete tasks in hard-to-access places and even escape cages. It could eventually be used as a hands-free soldering (焊接) machine or a tool for taking out swallowed items.
Carmel Majidi at Carnegie Mellon University and his colleagues created a millimeter-sized robot that can not only shape-shift, but also become stronger or weaker by alternating (交替) between being a liquid and a solid. When solid, the material was strong enough to support an object 30 times its own mass. To make it soften or melt as needed for different tasks, the researchers put it near magnets ( 磁 体 ), whose magnetic fields applied forces on the tiny magnetic pieces in the robot, moving them and changing the shape of surrounding metal in different directions. They also used a stronger field to pull the particles upwards, making the robot jump.
When Majidi and his colleagues used an alternating magnetic field, electrons in the robot's liquid metal formed electric currents. The coursing of these currents through the robot's body heated it up and eventually made it melt. Using this flexibility, the team made two robots carry and solder a small light bulb onto a circuit board. When they reached their target, the robots simply melted over the light bulb's edges to solder it to the board. Electricity could then run through their liquid metal bodies and light the bulb.
Finally, they shaped the robot like a Lego minifigure, then helped it escape from a cage by melting it and making it flow out between the bars.
The robots could be used for emergency fixes in situations where human or traditional robotic hands become impractical, says Li Zhang at the Chinese University of Hong Kong. For example, a liquefied robot might replace a lost part on a spacecraft by flowing into its place and then solidifying, he says.
