When carbon nanotubes are made, a mixture of single-, double- and multi-walled nanotubes are produced. The nanomaterials are also produced as a mix of both metallic and semiconducting tubes. This is a real problem when trying to make electronic devices from these structures because, ideally, either semiconducting or metallic tubes are needed depending on the application and not both. What is more, the tubes should either be predominantly single-, double- or multi-walled. Now, researchers in Germany and Australia have developed a new gel permeation method that can not only separate out double-walled tubes from the nanotube mix, but which can also distinguish the nanotubes by their electronic type. The purified tubes might now be used in real-world devices such field-effect transistors, sensors and transparent electrodes……
http://nanotechweb.org/cws/article/tech/60616
