Strain sensing of carbon nanotubes: Numerical analysis of the vibrational frequency of deformed single-wall carbon nanotubes

The potential applications as nanostrain sensors and tunable frequency oscillators make it important to analyze the natural vibrational frequency of deformed carbon nanotubes. We perform extensive molecular-dynamics and continuum analyses to explore the effects of several basic deformation modes (axial tension and compression, bending, torsion) on the vibrational characteristics of single-walled carbon nanotubes. The effects of nanotube length and chirality are also taken into account. It is found that the carbon nanotube is very sensitive to small axial strains, and tubes with smaller radii have higher sensitivities. The fundamental frequency of nanotube upshifts with tension and downshifts with compression, whereas the frequency shifts caused by bending or torsion are notably smaller. The results in this paper may be used to guide and design the application of carbon nanotubes as ultrasensitive strain sensors.