Circuits made from carbon nanotubes are intrinsically faster than those made from silicon. But while products from tennis rackets to bike frames take advantage of nanotubes' light weight and strength, no commercial devices have yet exploited their remarkable electrical properties.

That's partly because researchers have had difficulty creating films or other assemblies of nanotubes that preserve those properties: nanotube arrays, for example, proved nowhere near as electrically conductive as tubes taken singly. But a number of groups have found ways around that ­obstacle, and the result has been a flurry of prototype electronic devices that use nanotubes. Here is a sampling.