The world’s water resources are being increasingly degraded by a growing plague of harmful bacteria and microplastic pollutants, which can contaminate food chains and impact potable water quality. A robotic resolution for the removal of both of these pollutants simultaneously has been devised by researchers from Brno University of Technology in the Czech Republic.

Swarms of microscale robots are controlled by external magnetic fields to collectively capture microplastics and bacteria present in aquatic systems. The microbots are formed by linking strands of positively charged polymers to magnetic particles which are activated by the magnetic field, which is used to manage the movement and speed of the 2.8 micrometer-diameter bots.

Source: ACS Nano 2024, 18, 20, 13171-13183

As described in ACS Nano, laboratory tests assessed the utility of the microbots in removing 1- micrometer-wide fluorescent polystyrene beads and infectious Pseudomonas aeruginosa bacteria from a water tank. After being added to the tank, the cleanup bots were exposed to a rotating magnetic field for 30 minutes.

About 80% of the bacteria were captured at a robot density of 7.5 mg/ml, and the concentration of microplastics in the test environment was also observed to decline significantly. Robot removal was performed with a permanent magnet, after which the collected bacteria were detached with ultrasound and disinfected by ultraviolet radiation.

[See also: A snail-inspired robot promises to vacuum up microplastics from bodies of water]

These tiny workers offer a novel means of purifying water, as they can be reused for continual removal of microplastics and microbes.