Resonant Oscillators with Carbon-Nanotube Torsion Springs

Abstract

We report on the characterization of nanometer-scale resonators. Each device incorporates one multiwalled carbon nanotube (MWNT) as a torsional spring. The devices are actuated electrostatically, and their deflections, both low frequency and on resonance, are detected optically. These are some of the smallest electromechanical devices ever created and are a demonstration of practical integrated MWNT-based oscillators. The results also show surprising intershell mechanical coupling behavior in the MWNTs.

Multiscale modeling and simulation of nanotube-based torsional oscillators

“…This is because we only model the outermost tube of the multi-walled carbon nanotubes (MWNT) that were utilized in the experiments. With the consideration of fully mechanical coupling [9] between interlayer tubes, we predict the resonance frequencies (F 2 ), which are close to the experimental results for Devices 5, 6, 7, and 8. Furthermore, all the measured frequencies are in the ranges of numerical solutions.…”

“…To validate the proposed multiscale modeling, we employ the experimental outcomes of Papadakis et al [9] as the reference. They tested nine devices and Table 1.…”

“…The torque results from forces of the atoms located on the interface G int due to the torsion of nanotubes. It has been observed [9] that vertical deflections of nanotubes could be negligible compared to torsional deflections. Therefore, the torque T can be computed by:…”

“…Their extraordinary mechanical and electrical properties [2] ensure that CNTs will play an essential role in the design of nanoscale devices, such as nanotweezers [3], nanogears [4], nanotube motors [5], and axial nano-oscillators [6]. Recently, a nanoelectromechanical device [7][8][9] based on an individual CNT serving as a torsional spring and mechanical support has been successfully fabricated. Williams and co-workers [7,8] reported fabrication of nanoscale mechanical devices, which consist of a suspended lever, i.e., the ''paddle,'' connected by CNTs as torsion beams to stationary leads.…”

“…Williams and co-workers [7,8] reported fabrication of nanoscale mechanical devices, which consist of a suspended lever, i.e., the ''paddle,'' connected by CNTs as torsion beams to stationary leads. Papadakis et al [9] used similar techniques to synthesize so-called torsional oscillators. The metal paddles in their experiments were on CNTs so that the tubes were strained primarily in torsion.…”