Engineers Develop Morphing Robot That Uses Liquid Metal to Change Shape

Engineers from Virginia Tech have developed a new soft robot that can morph its shape and transform into different vehicles, including land rovers, quadcopters and swimming platforms. Like other soft robots, the team took inspiration from nature with organisms that can change shape to perform different functions, such as the octopus, which morphs to move, eat, and interact with its environment. To that end, if they were going to build a robot that could mimic the morphing power of octopi, they would need a robust material that could change shape, hold that shape and revert to its original configuration throughout many cycles without degradation.

To create a framework that could provide the ability to be morphed, the engineers studied the Japanese art of kirigami – making intricate shapes out of paper by cutting sections away, similar to making snowflakes in school. By observing the strength of those patterns within rubber and composite materials, the team was able to develop an architecture of a repeating geometric pattern. With the framework in place, they needed a material that could hold its shape and morph into another on-demand and devised an exoskeleton using a low melting point alloy (LMPA) embedded inside a rubber skin.

Usually, when metal is stretched beyond its limit, it becomes permanently bent, cracked, and deformed, but placing the LMPA within a rubber housing can hold a desired shape and become load-bearing. To return the meatal to its original shape, the team incorporated tiny heaters next to the LMPA mesh, which causes the metal to turn into a liquid at 600C. The rubber material holds the metal in place in its liquid state and pulls it back into its original shape, and once cooled, it again holds the shape of the structure.

The engineers tested the new material by combining it with a microcontroller, motors and other hardware to create a functioning rover that could transform into a flying drone and a submarine that could retrieve objects on the bottom of an aquarium. It will be interesting to see how this new material evolves with the ongoing development of soft robots.