Flexible nanocircuits can be shaped to fit any surface

The Stanford University team, led by assistant professor of mechanical engineering, Xiaolin Zheng (pictured centre), believes the method could be used to make everything from wearable electronics and flexible computer displays, to high efficiency solar cells and ultrasensitive biosensors. To create their nanowire based circuits, the researchers coated the surface of a silicon wafer with a thin layer of nickel before fabricating the electronic circuitry. According to Zheng, the nickel and silicon were easily penetrated when exposed to water after fabrication, which meant that the nickel and the overlaying electronics could be effectively detached from the silicon wafer. After applying the nickel layer to the silicon chip, the researchers also laid down an ultra thin layer of a polymer to act as an insulator and to provide mechanical support for the electronics. The 800nm polymer layer also proved to be extremely flexible, which allowed Zheng and her team to attach their nanowire electronics to a range of shapes and materials. These included paper, textiles, plastics, glass, aluminium foil, latex gloves and even a crumpled Coke can. "The polymer layers we used were about 15 times thinner than the plastic wrap you use to cover a plate of food," said Zheng. "Since the polymer had such a great degree of flexibility, we could wrap the polymer with nanowire devices on top over anything while conformally following the shape of any object." Because the nanowires were so short and flexible, they could be easily applied to a surface, removed and then applied to another surface, repeatedly, without degrading the circuitry. Zheng believes the new method could offer advances in biological research, high efficiency flexible solar cells and even robotics. "The possibilities are really unlimited," she concluded.