Stretchable Carbon Nanosprings Production by a Catalytic Growth Process

Due to their peculiar electromagnetic and mechanical properties, helical carbon nanotubes (HCNT) have important potential applications in micro and nanoelectromechanical fields where they can be used as springs, magnetic field detectors, electromagnets, inductors and actuators. We report here the synthesis ofcarbon nanosprings through a non-classical catalytic growth process using a nanoporous support, where the regular array ofopenings allows the control ofthe diameter and coil pitch ofthe nanosprings. Exposition ofsuch carbon nanosprings to a laser beam beyond an energy threshold can induce a permanent deformation characterized by the decoiling of the spring. Such permanent deformation results from an internal stresses relief mechanism, where pentagon-heptagon defect pairs reverting back to hexagon rings reduce the curvature of the coiled nanotube. This is expected to have important potential therapeutic applications in which carbon nanosprings can be located specifically in artery channels to remove fatty substances. They can also be located within cancer cells through specific interactions, after which the cells would be destroyed through the use ofa more energetic but not harmful laser light. Such energy application is expected to fragment HCNT into digestible carbon for assimilation by the human body.