The scientists took inspiration, surprisingly, from sea cucumbers, which are able to switch between soft and stiff states to protect themselves.
Researchers have once again turned science fiction into, well, just science by creating a Terminator-like robot that can melt and resolidify on command, all without sacrificing its strength.
This new robot combines the best aspects of both “stiff” robots — hard-bodied, typical robots — and “soft” robots — flexible but weak robots with difficult-to-control movement.
Chengfeng Pan, study leader and engineer at the Chinese University of Hong Kong, said in a press release, “Giving robots the ability to switch between liquid and solid states endows them with more functionality.”
The team’s study was published in the journal Matter, where they explained that this new phase-shifting material — the “magnetoactive solid-liquid phase transitional machine” — was created by embedding magnetic particles in gallium.
Gallium, it should be noted, is a metal with an incredibly low melting point of only about 85.6 degrees Fahrenheit (or 29.8 degrees Celsius).
“The magnetic particles here have two roles,” said Carmel Majidi, senior author and mechanical engineer at Carnegie Mellon University. “One is that they make the material responsive to an alternating magnetic field, so you can, through induction, heat up the material and cause the phase change. But the magnetic particles also give the robots mobility and the ability to move in response to the magnetic field.”
The researchers were inspired to create the device based on observations of sea cucumbers, which they noticed were able to alternate between “soft” and “stiff” states to protect themselves and increase the amount of weight they could carry.
The robot is only a millimeter wide and three millimeters tall, but tests conducted by the team determined that it can carry an object of 30 times its own mass while in its solid form.
To turn it into its liquid form, the researchers put it near magnets, which activated a process called magnetic induction. In other words, the magnets exerted a force on the smaller magnetic pieces in the robot, causing them to vibrate and heat up and form electric currents, shifting the metal around them as it reached its melting point.
The scientists were also able to use different magnetic fields to pull the robot in specific directions, including making it jump by pulling on it with a stronger magnetic field from above.
In one show of how manipulatable and flexible these robots could be, the research team had two minuscule robots transport a small light bulb on a circuit board, per New Scientist. To fuse the bulb to the board, the robots simply melted themselves and resolidified, allowing electricity to pass through them and into the light bulb.
They conducted a similar experiment inside an artificial stomach, exemplifying how these small robots could be used to, for example, remove objects in an instance where human or larger robot hands could not.
In this example, they used magnets to guide the robot to a small object, melt over it, and then carry it out.
Researchers also tried an experiment in which the robot, shaped like a Lego, melts down into its liquid state, escapes from a small prison, and then reforms into its Lego shape.
“Now, we’re pushing this material system in more practical ways to solve some very specific medical and engineering problems,” Pan said.
“Future work should further explore how these robots could be used within a biomedical context,” said Majidi. “What we’re showing are just one-off demonstrations, proofs of concept, but much more study will be required to delve into how this could actually be used for drug delivery or for removing foreign objects.”
Looking for more breakthrough stories in the world of robotics? Check out this tiny, breakdancing robot that was designed to go inside the human body. Or, see the flexible origami robot that can move on its own.