Robots inspired by sea cucumbers turn from liquid into solid

Miniature machines tested on an obstacle course could be used in surgery and engineering, say researchers

Shape-shifting robots inspired by sea cucumbers can rapidly change between liquid and solid, offering the possibilities of breakthrough treatments in medicine, new research shows.

The miniature robots could be used in surgery and might change the face of engineering, researchers said.

Traditional robots are hard-bodied and stiff, while “soft” robots have so far been flexible but weak, and difficult to control.

The sea cucumber can transform itself from solid into a liquid. They liquefy at will to pour their bodies into tight spaces and solidify again to hide from predators.

“Giving robots the ability to switch between liquid and solid states endows them with more functionality,” said Chengfeng Pan, an engineer at the Chinese University of Hong Kong, who led the study.

Researchers put their robots through an obstacle course of mobility and shape-morphing tests in a study, which was published on Wednesday in the journal Matter.

The team created a new material — called the “magnetoactive solid-liquid phase transitional machine” — by embedding magnetic particles in gallium, a metal with a very low melting point of 29.8°C.

They have also tested the material’s mobility and strength in a variety of contexts.

The robots jumped over moats, climbed walls and split in half to co-operatively move other objects around before joining back together.

In one video, a robot shaped like a person liquefies to ooze through a grid before reforming.

“Now, we’re pushing this material system in more practical ways to solve some very specific medical and engineering problems,” Mr Pan said.

On the biomedical side, the team used the robots to remove a foreign object from a model stomach and to deliver drugs on-demand into stomach.

They also demonstrate how soldering robots can ooze into hard-to-reach circuits and the can be a mechanical “screw” for assembling parts in hard-to-reach spaces.

“Future work should further explore how these robots could be used within a biomedical context,” said senior author and mechanical engineer Carmel Majidi of Carnegie Mellon University.

“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.”