The ins and outs of microbots

Mention the word ‘microbot’ and people will immediately think of science fiction films rather than a water treatment technology. Yet scientists believe they have found a way to engineer tiny robots which can zoom and clean up contaminated water sources.

Reported in the journal ACS Applied Materials & Interfaces, researchers Diana Vilela, Samuel Sánchez Ordóñez and colleagues set out to see if they could design microbots to remove waterborne bacteria.

The team designed ‘two-faced’ spherical particles to perform the task. One face is made with magnesium, which reacts with water to produce hydrogen bubbles to propel the microbots; the other face is made with alternating iron and gold layers topped by silver nanoparticles.

Bacteria sticks to the gold and are killed by the silver nanoparticles. Lab testing shows that the particles can motor around in water for 15 to 20 minutes before the magnesium is spent.

Initial data shows they trapped more than 80% E. coli in water spiked with a high concentration of the bacteria. Then, because of the iron’s magnetic properties, the microbots are removed easily with a magnet, without leaving behind any harmful waste in the water.

Researchers claim that adding more of the bots could further improve these figures.

Treatment of wastewater
A swarm of thousands of tiny microbots may also be the next solution in removing toxic heavy metals and contamination from industrial wastewater.

These microbots, called graphene oxided-based microbots (GOx-microbots), can remove 95% of lead in polluted water in one hour and be reused multiple times.

As part of the work, researchers designed tube-shaped GOx-microbots. A graphene oxide layer was used to absorb lead from wastewater, from 1 000 parts per billion (ppb) to below 50ppb in 60 minutes.

Meanwhile, a middle layer of nickel enabled the microbots’ direction to be controlled by an external magnetic field. Also, when they are finished, the magnetic field again can be used to collect them to be recovered and reused.

Finally, an inner layer of platinum enables the bots to propel themselves through water. This work is a step toward the development of a smart remediation system where we can target and remove traces of pollutant without producing additional contamination.

Smaller than a width of a human hair, it is hoped the development of the micro-bots may eventually offer a solution that is faster and cheaper than conventional methods.

Original articles on www.waterworld.com 

Caption: Watch how the microbots move about in a video from the Headline Science video below:

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