These Light-Powered Soft Robots Can Clean Up Ocean Water

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Scientists have developed a floating, robotic film that can clean the sea and drinking water. It uses water as fuel and takes power from light.

“Our motivation was to make soft robots sustainable and able to adapt on their own to changes in the environment. If sunlight is used for power, this machine is sustainable, and won’t require additional energy sources,” said UCR chemist Zhiwei Li. “The film is also re-usable.”

The film has been given the name of Neusbot after neustons which is a category of animals that includes water striders. These insects traverse the surface of lakes and slow-moving streams with a pulsing motion. This is how this film will behave in water.

There have been other films developed that could bend in response to light but the properties of this one are unique as this can create adjustable and mechanical oscillations in water.

Technical details of this achievement are described in a new Science Robotics paper

“There aren’t many methods to achieve this controllable movement using light. We solved the problem with a tri-layer film that behaves like a steam engine,” Li explained. 

The way Neusbot takes power from light is the same as the earlier trains derived power from steam. The middle layer of the film has pores. It holds water, iron oxide, and copper nanorods. The nanorods transform light energy into heat, vaporizing the water and powering pulsed motion across the water’s surface.

The last layer of Neusbot is hydrophobic. This means that even if it gets buried in the water due to pressure or large waves, it will come back floating on top.  Also, the film can tolerate high salt concentrations without damage. “I’m confident about their stability in high salt situations,” Li said. 

Light-powered soft robots could suck up oil spills

Li and UCR chemistry professor Yadong Yin specializes in making robots from nanomaterials. His team powered Neusbot with sunlight. Also, the direction can be controlled with artificial light as well to see where Neusbot swims and cleans. 

Currently, Neusbot has three layers. However, in the future, the team aims for a fourth layer as well that can absorb oil or other chemicals. 

“Normally, people send ships to the scene of an oil spill to clean by hand. Neusbot could do this work like a robot vacuum, but on the water’s surface,” Li said. 

The team is also trying to manipulate the oscillations of the film so more control of its function can be achieved.

“We want to demonstrate these robots can do many things that previous versions have not achieved,” he said. 

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