Calibration of Carbon Nanotube Probes for Pico-Newton Order Force Measurement Inside a Scanning Electron Microscope

Abstract

A method is presented for pico-Newton (pN) order force measurement using a carbon nanotube (CNT) probe, which is calibrated by electromechanical resonance. A CNT probe is constructed by attaching a CNT to the end of a tungsten needle or an atomic force microscope (AFM) cantilever using nanorobotic manipulators inside a field-emission scanning electron microscope (FE-SEM). Conductive electron-beam-induced deposition (EBID) is used for the fixation of CNTs with an internal vaporized precursor W(CO)6. For manipulating them easily and quickly, CNTs are dispersed in ethanol by ultrasonic waves and oriented on copper electrodes by electrophoresis. The elastic moduli of CNT probes are calibrated for use as a force measurement probe by electrically exciting at fundamental frequency. We analyzed the resolution of force measurement using a CNT probe. This force measurement can be used to characterize the mechanical properties of nanostructures and to measure friction or exfoliation forces in nanometer order.