Light-activated robot fish collects microplastics in water

Researchers supported by the American Chemical Society have developed a fish-shaped robot that can swim and collect microplastics from the water. Light-activated robotic fish could be used to help collect the estimated twenty-four trillion pieces of microplastic found in oceans globally.

The fastest robot of its kind

In current approaches, soft robots are made with hydrogels and elastomers, but because they are easily damaged in the aquatic environment, the team developed a material inspired by the mother-of-pearl found on the inner surface of some mollusks, such as clams, to increase the robotfish’s durability.

To mimic the gradient structure of nacre, the researchers created composite nanolayers of sulfonated graphene with molecules with hydrophobic cores and hydrophilic exteriors. These layers were then incorporated into polyurethane latex mixtures at different concentrations and were combined layer by layer. With these couplings, the team developed a small 15mm long robot fish.

The robot fish can move 2.67 body lengths per second using a near-infrared light laser that pushes the tail forward when quickly opened and closed. The team says this speed is higher than other soft-swimming robots, and about the same as active phytoplankton moving in water.

In the tests carried out, it was seen that the robot fish can repeatedly collect the polystyrene microplastics around it and transport them to another place. In addition, the robot can heal itself at a high rate after being cut and maintains its adsorption abilities.

The researchers say that the developed robot fish can remove microplastics and other pollutants from water in harsh aquatic environments thanks to its durability and speed, leading to robots that can be created for similar purposes.