This extreme stiffness, along with low density, might make carbon nanotubes an excellent ingredient in building materials.
Electrical properties are potentially no less important.
This affords a more controlled study of conductivity than was possible in previous two-probe experiments. The four-probe tests have yielded nanotubes with a wide range of properties, from metallic to semiconducting. The researchers conclude that a tube's conductivity depends greatly on its diameter and on the helicity of carbon atoms making up the layers of the tubes.