This publication deals with the design of carbon nanotubes (CNT) based nano-electromechanical system (NEMS)
consisting in a variable capacitor working at microwave frequencies. This device is based on an array of moveable CNT
cantilever electrostatically actuated over a ground plane (figure 1 and 2). To design this component, a time-efficient
numerical algorithm for the prediction of CNT electromechanical behavior has been developed. This numerical tool
permits to calculate the pull-in voltage and flexion of the CNT's tip for various devices' parameters like CNT's diameter
and length, initial air gap (g) ... Our software also takes into account the Van der Waals (VdW) forces and the fringing
field effects. The results demonstrate that, unlike for RF-MEMS, fringing field effects are preponderant for CNT-based
This paper also discusses on the accuracy of the developed software. In order to validate our prediction, we used
finite element simulation software : COMSOL® and experimental results found in literature and compare them to our
prediction. Results prove that we obtain, for a decrease of the simulation time by two orders of magnitude, a maximum
error on the pull-in voltage of 7% for various kinds of structures and dimensions.
These results were finally used for the design of NEMS demonstrators. The microwave behavior of the varactors,
over a large range of frequency, is presented. Simulations with 3D finite-element-method electromagnetic software were
performed to optimize the structure and predict its microwave performances, which conclude the design of our
microwave carbon nanotubes (CNT) based nano-electromechanical system (NEMS) variable capacitor.