Carbon Nanotube Electromechanical Devices

Abstract

Carbon nanotubes (CNTs) have been expected to be excellent materials for building blocks of miniaturized electromechanical devices, because of their unique electrical and mechanical properties. In this report, we demonstrate CNT molecular devices of linear motors and torsional actuators. The linear motors have a single-walled CNT (SWNT) capsule with 3-8 nm in length encapsulated in interior of a SWNT with a hollow free space of 8-20 nm in length (see Fig. 1). [1] The CNT capsules were prepared by thermal coalescence of C60 molecules in SWNTs. The hollow free spaces were sealed with capped inner CNTs. The CNT capsules move back and forth in the free space with thermal energy. One of applications of such linear motors is a high frequency (GHz order) oscillator. A relatively thick CNT is flattened at room temperature because its tubular state has higher energy. We have revealed that a flattened and twisted state changes to a tubular state by applying electric current to the CNTs, and this transition is reversible and generates torque. [2] This finding brought us a new concept of torsional actuators (see Fig. 2). Controlling the amount of current applied to the CNTs enable us to adjust the rotation angle of the free end.