Multiwalled Carbon Nanotube/Nanofiber Arrays as Conductive and Dry Adhesive Interface Materials

We demonstrate the possibility of making conductive and dry adhesive interfaces between multiwalled carbon nano-tube (MWNT) and nanofiber (MWNF) arrays grown by chemical vapor deposition with transition-metal as catalyst on silicon substrates. The maximum observed adhesion force between MWNT and MWNF surfaces is 3.5 mN for an apparent contact area of 2 mm by 4 mm. The minimum contact resistance measured at the same time is ∼20 Ω. Contact resistances of MWNT-MWNT and MWNT-gold interfaces were also measured as pressure forces around several milli-Newton were applied at the interface. The resulting minimum contact resistances are on the same order but with considerable variation from sample to sample. For MWNT-MWNT contacts, a minimum contact resistance of ∼ 1 Ω is observed for a contact area of 2 mm by 1 mm. The relatively high contact resistances, considering the area density of the nanotubes, might be explained by the high cross-tube resistances at the contact interfaces and limited inter-penetration of the nanotube arrays.