Researchers from the Israeli Technion University developed a novel and rapid method to optically visualize CNTs and graphene. The idea is that growing pNBA nanocrystals - which are optically visible on top of the CNTs or graphene sheets. This allows the crystals to be viewed by dark-field optical microscopy.
The pNBAs NCs can be easily removed - and the original material is not effected by this process. But it allows much easier study of graphene, and can also be used to aid production processes as it is a scalable, fast and cost-effective process. The video below shows how growing those NCs on carbon nanotubes makes the tubes visible.
The researchers tested this method successfully on graphene flakes (exfoliated graphene), CVD graphene and graphene nanoribbons. One specific advantage of this method is that it allows top optically see graphene on substrates that do not support constructive interference - for example for 285-nm SiO2