Cooperative Multiwalled Carbon Nanotubes for Enhanced Force Spectroscopy

Abstract

The increased interest to develop novel nanostructured devices, such as those intended for molecular nanoelectronics, requires the development of advanced characterization. We present the properties of carbon nanotube (CNT) atomic force microscopy (AFM) probes for testing multiple properties of nanometer structures, including force spectroscopy. The CNT-AFM probes are made by integrating a high density of MWCNTs in the tip of the probe. In particular, the modulation of the original probe mechanical response due to CNTs in approach-retraction curves is shown, as a consequence of the collective response of the high density of CNTs existing at the tip apex. Illustrative of the potential of the CNT-probe device, the actual determination of physical parameters on HOPG is provided, as a proof of CNT-mediated access to the specific characteristics of the sensed surface. The features observed for the establishment of tip-sample electro-mechanical contact (snap-in and adhesion) reveal the particular interaction forces that are exerted to the CNT tip. The high sensitivity of CNTs to record interaction events comprises both attractive and repulsive mechanisms. Specifically, results suggest the CNT-AFM probe capability to monitor long and short range forces in relation to external electric field and sample charges, capillarity, adhesion and so on. When combined with electrical current monitoring is of extreme precision for conductance determination. [DOI: 10.1380/ejssnt.2012.341]