Driving magnesium micromotors with seawater

22-May-2013 - USA

Scientists in the California have developed magnesium-based Janus micromotors that self-propel in seawater. Research shows how the micromotors can be used to capture and transport oil droplets from contaminated seawater, presenting a possible environmental application for the removal of oil spills at sea.

The scientists based the development of the self-propelling micromotors around the reaction of magnesium and water to produce bubbles of hydrogen gas. They asymmetrically coated Mg microparticles with layers of Ti, Ni and Au to form the Janus micromotors then immersed them into seawater. The oxidation of the Mg surface produces hydrogen bubbles that propel the microparticles, demonstrated by time-lapse images over a period of 4 seconds. A magnet was used to guide the direction of propulsion.

To demonstrate a practical application of the new seawater-driven micromotors, the scientists modified them with self-assembled monolayers of alkanethiols. Using further time-lapse images, they showed that the hydrophobic micromotors could capture and transport droplets of motor oil in a sample of seawater.