Swarms of Tiny Robots Remove Microplastics From Soil and Water

Scientists from the Czech Republic have created microscopic cleanup robots that successfully removed microplastics from both soil and aquatic environments in the lab. Details of their work are published in the journal npg Asia Materials. To build the robots, researchers started with microscopic MXene particles made of ultrathin, stacked layers. The material has a large surface area and surface chemistry that help it attract and hold plastic. They then coated the particles with magnetic nickel nanoparticles so rotating magnetic fields could drive the tiny robots.

Then came the testing phase. The team placed swarms of these microbots into water and soil samples contaminated with plastic. The externally generated magnetic fields made the robots spin and tumble through the liquid and squeeze through tiny water-filled gaps in the soil. “In soil environments, the microrobots can navigate through water-permeated soil microenvironments, actively disrupt microplastic entrapment within soil matrices, and extract them,” the study authors commented in their paper. As they moved, their sticky surfaces collided with microplastics, binding to them and dragging them along. The researchers then used a magnet to pull the microrobots, along with their trapped plastic cargo, out of the samples.

They performed well. In water, they removed about 94% of test polystyrene particles and 89% of PET (polyethylene terephthalate) in around an hour. In the model soil, they removed about 81% of the polystyrene and 72% of PET. This outperformed the same MXene material used without magnetic motion, which relied on passive adsorption rather than actively moving through soil and water.