SWCNT synthesis methods each time produce mixtures of different SWCNTs, with very different optical and electronic properties. To embed SWCNTs in actual applications, sorting of SWCNTs by their helicity and diameter (i.e. their chiral structure) and thus also by their peculiar optical and electronic properties is essential. This can be achieved in many ways, using different techniques such as density gradient ultracentrifugation (DGU) and aqueous two-phase extraction (ATPE).
