Above: Nanotube height, diameter and spacing affect the densification process. If the nanotube bundles are too short, like those on the left, there is no densification at all. If the bundles are too tall, like those on the right, bundles are not rigid enough and tend to stick with one another after densification. The middle region, where bundles are between 30-65 micrometers tall, demonstrates good densification.
By Michael Mullaney Rensselaer researchers have developed a new method of compacting carbon nanotubes into dense bundles.

These tightly packed bundles are efficient conductors and could one day replace copper as the primary interconnects used on computer chips and even hasten the transition to next-generation 3-D stacked chips.

Theoretical studies show that carbon nanotubes, if packed closely enough together, should be able to outperform copper as an electrical conductor. But because of the way carbon nanotubes are grown — in sparse nanoscale “forests” where carbon molecules compete for growth-inducing catalysts — scientists have been unable to successfully grow tightly packed bundles.