carbon nanotube.
Carbon nanotube(CNT) is an allotrope of carbon. There are two types of CNT namely single walled carbon nanotube(SWNT) and multi walled carbon nanotube(MWNT). Single walled carbon nanotube is a one thick sheet of graphite(graphene) rolled up into a seamless cylinder with diameter of the order of a nanometer. In SWNT the length to diameter exceeds 1,000000. Multi walled carbon nanotube is made up of a number of concentric tubes.