Scientists have created a bionic, self-propelled robotic fish that can “eat” microplastics and repair itself if damaged mid-mission.

Microplastics—the minute pieces of plastic created when larger plastic products from bags to tires break down—have been found everywhere we’ve bothered to look for them: the top of Everest, the ocean depths, in our food and drink and even in our blood. It’s estimated people consume a credit card’s worth of plastic every week, and plastic flows into the ocean every day. Marine life often mistakes aquatic microplastics for food, leading to clogged intestines and starving animals. What isn’t eaten drifts to the bottom of the ocean and settles in benthic crevices.

Enter the robo-fish created by Sichuan University researchers. Roughly half-an-inch long, it self-propels through the water at more than an inch per second, using near-infrared light lasers to rapidly flap its tail. Made of nacre, a layered composite that mimics a clam’s mother of pearl interior, the flexible bot can twist and bend.

As they move around, these fish “eat,” or absorb, free-floating microplastics and chemicals in the water. The materials the fish is made of interact with organic dyes, antibiotics and heavy metals in microplastics, causing strong chemical bonds and electrostatic interactions. In this way, the robots latch onto these particles and chemicals, remove them from the water, and transport them elsewhere. Each robo-fish can pull up to 11 pounds, the scientists said.

“After the robot collects the microplastics in the water, the researchers can further analyze the composition and physiological toxicity of the microplastics,” says Polymer Research Institute’s researcher Yuyan Wang, one of the project's lead researchers.

The new also material has regenerative abilities. Wang specializes in self-healing materials, and the robo-fish can heal itself to 89 percent of its ability, even after damage or cutting, which is likely in polluted waters. Critically, this means the fish will continually absorb microplastics and can help monitor marine pollution levels in harsh habitats.

This prototype remains a proof of concept still and much more research is needed, Wang notes. The bionic fish currently only works on water surfaces, but her team is working on a more complex robot that can go deeper.

“I think nanotechnology holds great promise for trace adsorption, collection, and detection of pollutants, improving intervention efficiency while reducing operating costs,” she says.