Chinese scientists have developed a fish-shaped light-actuated swimming robot that can "eat" microplastics in water bodies and repair itself if damaged.

Microplastics, pieces of plastic smaller than 5 millimeters, are numerous and widely distributed in the ocean.

They are easily eaten by marine organisms and transmitted through the food chain, presenting a serious threat to human and ecosystem health.

Inspired by nacre, also known as mother of pearl, a strong, durable and flexible material obtained from hard clam shells, scientists from Sichuan University modeled nacre's graphene-based gradient nanostructure to create a durable, flexible and self-repairing nanocomposite, according to a study published in the journal Nano Letters.

The research team then used the new material to develop a 15-mm fish-like soft robot, enabling it to swim rapidly and absorb microplastics in water.

"Soft robots need to have high adaptability and environmental tolerance when working in complex water environments," said Wang Yuyan, the first author of the research paper, who added that existing soft robots are generally made of hydrogels or silicone rubber, which are inherently mechanically inferior, easily damaged and have difficulty integrating functions.

The study showed that compared with traditional uniformly dispersed material structures, the new material used in the fish-shaped soft robot has many supramolecular interactions between layers, allowing the robot to recover its robustness and functionality even when damaged and continue its microplastic harvesting operations.

The robotic fish can swim at a speed of 2.67 times its body length per second, exceeding the speeds of previously reported soft swimmers and comparable to the speed of plankton.

At present, the soft robot can only integrate the function of directionally collecting microplastics from the water surface. All these functions need to be optimized and improved before large-scale application.

The researchers are currently working on a new material that could detect microplastic contaminants underwater and share live data online, the paper said.

The new nanostructural design is expected to offer an effective extended path to other integrated robots and to be applied in many fields such as solar power generation, chemical reaction catalysis, biomedicine and aerospace.