• Tiny robots actively chase nanoplastics instead of waiting for contact
• Electrostatic attraction lets nanobots grab plastic-like charged surfaces
• Magnetic control allows precise movement without fuel or light

There is a lot of plastic waste in the world, which is endangering the environment, and tiny particles of these plastics are now contaminating drinking water.

These particles, called nanoplastics, are so small that they can pass through conventional water filters, enter human organs, and cause diseases such as cancer.

Researchers at the Brno University of Technology have developed a small magnetic robot that can search for and eliminate these minute particles from water.

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How the tiny robots catch plastic particles

The research, published in Environmental Science: Nano, found these nanorobots use electrostatic attraction to remove nanoplastics in the same way a balloon clings to your hair.

"What stands out is how these robots are designed to attract plastics using electrostatics," said Sylvain Martel, a computer engineer who was not involved in the work.

The robots come with hexagonal rods formed from iron-based metal-organic frameworks, and each rod is roughly the width of a human hair.

Under a scanning electron microscope, each rod resembles a cratered meteorite, with pores that become sites for nanoplastics to latch onto.

These rods were then heated, which caused them to rearrange into magnetic compounds, allowing the robots' movement to be controlled externally by magnets.

These robots operate using low-energy magnetic fields and require no additives, making them more efficient than designs that use fuels or ultraviolet light.

After extracting the plastic, a simple magnet is used to pull the bots to the glass wall so the cleaned water can be poured off.

Previous efforts to clean up plastic using nanobots relied on passive capture, simply placing the bots in water and waiting for nanoplastics to drift close enough to stick.

The new study flips that approach by sending robots out to actively seek the particles instead.

"If it's just particles sitting there hoping to attract nanoplastic, we don't call it a robot," said Martin Pumera, the lead researcher. "The whole idea is active matter."

In laboratory tests, the moving robots captured 78% of particles after one hour, which was roughly 60% more than when the bots sat completely still.

Real-world limitations

As the robots are used for the cleanup of water, they degenerate, which is one of the issues of this technology.

Though an acid bath can regenerate the robots, their performance declines after four reuse cycles as pores become clogged.

When tested in simulated seawater and groundwater, the bots' efficiency dropped by about 70% because dissolved ions competed with nanoplastics for the robots' electrostatic attraction.

Because the robots move only a few micrometers per second and the magnetic fields decay rapidly with distance, scaling up is a challenge.

Conventional plants process millions of gallons per day, but these robots crawl so slowly that they would take an impractical amount of time to clean even a tiny fraction of that volume.

The dramatic efficiency drop in saltwater and groundwater also raises questions about real-world viability.

As interesting as this technology sounds, it is most likely a clever laboratory demonstration rather than a scalable solution to the growing crisis of nanoplastic contamination in drinking water.

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