Soft aquatic robot activated by light and magnets to quickly crawl

Researchers at Northwestern University have developed a new soft robot that can walk at roughly the speed of a human, activated by light and magnetic fields. The robot can squeeze into tight spaces and pick up, carry and release objects on demand.

The robot resembles a four-legged octopus, measuring about 1 cm (0.4 in) wide. It’s made mostly of hydrogel, encasing a scaffold of nickel nanowires and contains specially designed polymer molecules, and it’s this combination of materials that allows it to walk through water.

Normally the bot lies flat, but when exposed to light the molecules embedded in it become hydrophobic – that means it repels the water around it, bending the robot into a standing shape like a table. Once in that state, exposing it to a rotating magnetic field will cause it to walk towards the source, courtesy of its nanowire skeleton.

While most of these kinds of robots crawl along at a snail’s pace, the team says that this one can walk at a reasonably fast rate of about one step per second, comparable to a human’s casual saunter.

“By combining walking and steering motions together, we can program specific sequences of magnetic fields, which remotely operate the robot and direct it to follow paths on flat or inclined surfaces,” says Monica Olvera de la Cruz, co-lead author of the study. “This programmable feature allows us to direct the robot through narrow passages with complex routes.”

Once its work is done, the robot can be deactivated by simply switching off the light, which relaxes it back into its old flat shape. When it’s next needed, it can be reactivated by switching on the light and the magnetic field once again.

The robot isn’t just walking for the sake of it though. The team says that it can carry objects, either by wrapping its legs around them and rolling, or sticking things to its back and crawling. Once it reaches its destination, it can release the cargo by inverting itself, or shaking the sticky objects off by spinning, almost like it’s breakdancing.

The researchers say the soft robot platform could eventually be shrunk down and used to catalyze chemical reactions and pump out the resulting products, clean up water of pollutants, or deliver drugs in the body.

The research was published in the journal Science Robotics. The team demonstrates the soft robot in the video below.

Sea creature-inspired robot walks, rolls, transports cargo

Source: Northwestern University

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