Device Skates Between Oil, Water

Abstract

Taking inspiration from water-striding insects, researchers have constructed a device that can skate at the interface between oil and water (ACS Nano, DOI: 10.1021/nn301550v). The feat is enabled by a coating on the device’s legs that repels oil underwater. Such coatings could keep bugs from sticking to car windshields, scientists think, and enable robots to move through and clean up oil spills. Researchers had previously discovered that water striders’ legs work through the chemistry and physics of microprojections lined with nanogrooves on the bugs’ legs (Nature, DOI: 10.1038/432036a). Shutao Wang, of the Chinese Academy of Sciences, thought that he could use similar structures to solve a materials problem: Most materials that repel oil don’t work if they come into contact with water. To make a rough nanoscale coating that approximates the texture of the insects’ legs, Wang’s group immersed copper wires in aqueous ammonia. The ensuing reaction produced flowerlike microclusters ...