Jan. 26 () –
Inspired by sea cucumbers, engineers have designed miniature robots that quickly and reversibly change from liquid to solid, in the style of the villain from Terminator 2.
In addition to shapeshifting, the robots are magnetic and electrically conductive. The researchers put the robots through an obstacle course and mobility and shape-shifting tests, including a tiny human-shaped model that through the bars of a cell changing state. The study was published on January 25. in Matter magazine.
The team created the new phase change material – called “solid-liquid phase transition magnetoactive machine”– embedding magnetic particles in gallium, a metal with a very low melting point (29.8 °C).
“Magnetic particles have two functions,” explains Carmel Majidi, lead author and a mechanical engineer at Carnegie Mellon University. “One is that they make the material respond to an alternating magnetic field, so that you can, by induction, heat the material and cause the phase change. But magnetic particles also give robots mobility and the ability to move in response to the magnetic field.”
This is in contrast to existing phase change materials, which rely on heat guns, electrical currents, or other external heat sources to induce the transformation from solid to liquid. The new material also features an extremely fluid liquid phase compared to other phase change materials, whose “liquid” phases are considerably more viscous.
While traditional robots are hard and rigid, soft ones have the opposite problem: they are flexible but weak, and their movements are difficult to control. “Giving robots the ability to switch between liquid and solid states gives them more functionality,” says Chengfeng Pan, an engineer at the Chinese University of Hong Kong who led the study.