Device developed to help clean up deep-sea oil spills

Science : Inspired by the design of cactus plants, researchers have developed a device for extracting oil droplets from a body of water. Cacti extract water from the air via their conical-shaped needles. When a droplet lands on a needle, the drop’s naturally circular shape gets distorted, which creates surface tension. As the droplet tries to relieve that tension by regaining its circular shape, it is forced to move from the needle’s tip toward the base, where the water is then sucked into the plant’s pores. Now Lei Jiang of the Chinese Academy of Sciences in Beijing and colleagues have applied that principle to cleaning up oil spills. Not all oil spilled into the ocean floats; seawater can chemically transform the oil into denser micrometer-sized droplets that sink. To collect those droplets, the researchers created an oleophilic array of conical needle structures that mimic cacti by capturing the tiny drops and transporting them toward the needles’ base, where they can be sucked up by an oil tanker. Although intriguing, the technique may not be able to handle large spills, cautions Igor Mezić, who is an oil-spill expert at the University of California, Santa Barbara.