Researchers develop soft aquatic robots activated by light and magnetic fields

2024-03-04

Researchers at Northwestern University in the United States have developed a new type of soft robot that can walk at roughly the same speed as humans under the activation of light and magnetic fields. This robot can squeeze into narrow spaces and pick up, move, and release objects according to needs.

The robot is like an octopus, about 1 centimeter (0.4 inches) wide. It is mainly made of hydrogel, coated with nickel nanowire scaffold, and contains specially designed polymer molecules. It is the combination of this material that enables it to walk in water.

Under normal circumstances, robots are lying flat, but when exposed to light, the embedded molecules become hydrophobic - meaning they repel the surrounding water, bending the robot into a standing shape like a table. Once in this state, exposing it to a rotating magnetic field will cause it to move towards the light source under the action of the nanowire skeleton.

Although most of these robots crawl at a slow speed, the team stated that the walking speed of this robot is quite fast, about one step per second, comparable to a human's casual walk.

"By combining walking and turning movements, we can program specific magnetic field sequences to remotely operate robots and guide them to follow paths on flat or inclined surfaces," said Monica Olvera de la Cruz, co lead author of the study. "This programmable feature allows us to guide robots through narrow channels and complex routes."

Once its work is completed, the robot can be deactivated by simply turning off the lights, which will allow it to relax to its original flat shape. The next time you need it, simply turn on the lights and magnetic field again to reactivate it.

However, this robot is not just walking for the sake of walking. The team stated that it can carry objects, wrap its feet around them to roll, or stick things to its back to crawl. Once it reaches its destination, it can release the cargo by standing upside down or by spinning to shake off sticky objects.

Researchers say that this soft robot platform can eventually shrink and be used to catalyze chemical reactions and extract the resulting products, clean up pollutants in water, or deliver drugs in the body.

The study was published in the journal Scientific Robotics.

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