Micro-Submarines Clean Up Oil Spills One Drop at a Time
Fire boat response crews battle the blazing remnants of the off shore oil rig, Deepwater Horizon on April 21, 2010. The rig, located 51 miles southeast of Venice, Louisiana, exploded on April 20, 2010.
Someday a fleet of newly designed "micro-submarines" may assist in cleaning up oil spills, one droplet at a time.
The vehicles, 6 to 7 microns long (about 1/10th the thickness of a piece of paper) and 1 to 2 microns in diameter, are shaped like cones. Each one can carry 10 times its volume in recovered oil.
Nanoengineer Joseph Wang of the University of California, San Diego and his colleagues constructed the "submarines" from platinum, nickel and gold, a polymer known as PEDOT and a water-repellent, oil-attracting coating. The vehicles, 6 to 7 microns long (about 1/10th the thickness of a piece of paper) and 1 to 2 microns in diameter, have platinum on the inside. The platinum reacts with hydrogen peroxide to create bubbles, which propel the vehicles.
Wei Gao, a graduate student in Wang's lab and a co-author on the new paper describing the subs, explained that each tiny vehicle, or "motor," has a carrying capacity of "tens, or even 100 droplets" of oil, which the machines pick up due to their water-repellent, oil-loving surface. Loaded with more than 40 oil droplets, the vehicle travels at about 11 microns (almost two body lengths) each second.
The nickel layer between the platinum and the hydrophobic (water-repellent) layer is magnetic, so the submarines can be guided. "We use a magnet; you can also use an MRI machine," Gao said. This would allow the subs to be placed in an oil-contaminated area and then herded to a collection tank for removal. If the machines stop moving, throw a little more hydrogen peroxide in the spill.
The machines are similar in design to micromachines that have been proven to carry medicines though the bloodstream or capture various proteins inside the human body, but these are the first designed expressly for environmental remediation. [Microrobots Could Treat Diseases from Inside Your Bloodstream]
Even though the diminutive subs can carry up to ten times their volume in oil, cleaning a spill of any size would require a huge number of machines. That's no problem, Gao said. "We can make a million in half an hour. It's very easy to prepare."
While the vehicles have been tested, they aren't ready for use yet. The research was published in the April 5 edition of ACS Nano.