Young's Modulus of Nanowires Measured by Electrostatic Attraction: Application to Multi-Walled Carbon Nanotubes

An electrostatic experiment, performed inside a Field-Emission Scanning Electron Microscope equipped with two electrical probes, is used for the accurate determination of the Young's modulus of as-grown nanowires. One electrode being in contact with the substrate and the other one at close distance to the nanowire's tip, an electrical bias was slowly ramped up to attract and eventually bring the nanowire into contact with the attracting probe. While the SEM was shut down during this procedure to avoid electrical perturbation, the threshold bias that results in the eventual contact was determined from an I-V curve recorded simultaneously. Despite the impossibility of visualizing the nanowire's motion during this operation, a direct relationship can be established between that threshold bias, the corresponding deflection and the nanowire's Young's modulus. This technique, consisting essentially of two SEM images and one I-V curve, was applied to multi-walled carbon nanotubes of various lengths and orientations and resulted in an accurate Young’s modulus of 0.92 +/- 0.28 TPa.