Take a pinch of carbon nanotubes, add a dash of water, and what do you get? The answer, rather surprisingly, is almost anything you want. While most work to date would lead one to think of carbon nanotubes as stiff rods just a few nanometres across, Vladimir Tsukruk and his colleagues at Iowa State University in Ames have found that all this changes when the nanotubes are wet. They become very flexible and will spontaneously bend into interesting forms as they dry. By cycling through many wetting and drying operations, they have found loops, hooks, coils and other shapes. In addition to the obvious interest in bent nanotubes as possible structural components for nanodevices, the expected change in their optical properties in response to bending also makes them possible candidates for sensors.
Further reading
V V Tsukruk, H Ko and S Peleshanko 2004 Phys. Rev. Lett. 92 065502.