Swarms of Miniature Robots Simultaneously Clean Up Microplastics and Microbes
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When old food packaging, discarded children’s toys and other mismanaged plastic waste break down into microplastics, they become even harder to clean up from oceans and waterways. These tiny bits of plastic also attract bacteria, including those that cause disease. In a study in ACS Nano, researchers describe swarms of microscale robots (microrobots) that captured bits of plastic and bacteria from water. Afterward, the bots were decontaminated and reused.
The size of microplastics, which measure 5 millimeters or less, adds another dimension to the plastic pollution problem because animals can eat them, potentially being harmed or passing the particles into the food chain that ends with humans. So far, the health effects for people are not fully understood. However, microplastics themselves aren’t the only concern. These pieces attract bacteria, including pathogens, which can also be ingested. To remove microbes and plastic from water simultaneously, Martin Pumera and colleagues turned to microscale robotic systems, comprised of many small components that work collaboratively, mimicking natural swarms, like schools of fish.
To construct the bots, the team linked strands of a positively charged polymer to magnetic microparticles, which only move when exposed to a magnetic field. The polymer strands, which radiate from the surface of the beads, attract both plastics and microbes. And the finished products—the individual robots—measured 2.8 micrometers in diameter. When exposed to a rotating magnetic field, the robots swarmed together. By adjusting the number of robots that self-organized into flat clusters, the researchers found that they could alter the swarm’s movement and speed.
In lab experiments, the team replicated microplastics and bacteria in the environment by adding fluorescent polystyrene beads (1 micrometer-wide) and actively swimming Pseudomonas aeruginosa bacteria, which can cause pneumonia and other infections, to a water tank.
read more at ecomagazine.com.
