Modeling the static response and pull-in instability of CNT nanotweezers under the Coulomb and van der Waals attractions

•Instability of CNT nanotweezers is investigated using a nano-scale continuum model.•Three different approaches are employed to solve the governing equation.•The maximum stable arm length and the minimum gap between the arms are determined.•van der Waals force reduces the instability deflection and voltage of the nanotweezers.•van der Waals force might be neglected for a wide range of real applications.

In this paper, the static response and pull-in instability of nanotweezers fabricated from carbon nanotubes (CNT) are theoretically investigated considering the effects of the Coulomb electrostatic and van der Waals molecular attractions. For this purpose, a nanoscale continuum model is employed to obtain the nonlinear constitutive equation of this nano-device. The van der Waals attraction is computed from the simplified Lennard-Jones potential. In order to solve the nonlinear constitutive equation of the nanotweezers, three different approaches, e.g. developing a lumped parameter model, applying the analytical modified Adomian decomposition (MAD) and using a commercial numerical integration routine, are employed. The obtained results are in good agreement with experimental measurements as reported in the literature. As a case study, we have investigated a freestanding nanotweezer and have determined the detachment length and minimum initial gap. Furthermore, range of dominancy of the molecular attraction has been discussed.