Analysis of a microelectromechanical system testing stage for tensile loading of nanostructures

Abstract

A new analytical model is developed for interpreting tensile loading data on "templated carbon nanotubes" (T-CNTs, amorphous carbon nanotubes made by pyrolysis with the channels of nanopores in anodized alumina nanopore arrays) obtained with a microelectromechanical-system (MEMS)-based mechanical testing stage. It is found that the force output from the actuation unit of the testing stage depends on the stiffness of the force sensing beam and the nanostructure being loaded, as well as the power input. A superposition method is used to treat the mechanics of the device structure in the linear elasticity response regime. To our knowledge this is a new approach for solving the mechanical response of MEMS structures with variable force output and of the configuration described herein. An in situ mechanical testing of individual T-CNTs was undertaken in a scanning electron microscope (LEO1525) using a new device fabricated with integrated electrodes for controlled deposition of T-CNTs by electric-field guided assembly in a liquid. The T-CNT was subsequently tensile loaded to the point of fracture. The calculated modulus of the T-CNT using the new model based on the experimentally measured displacement of the moving platform with and without the T-CNT attached falls within the range expected for amorphous carbon. The new model corrects the treatment in a previously presented model [S. Lu , Rev. Sci. Instrum. 75, 2154 (2004)].