Determination of ultra light weight masses using AFM and FIB technology

Abstract

Atomic Force Microscopy (AFM) has evolved as a powerful tool to resolve topographic information of specimens at the nano-scale level. The operating principle of an AFM makes use of the signal detected from the cantilever tip, which may either be a direct measure of the deflection of a laser beam or changes in the frequency of vibration when it interacts with the specimen. The use of the AFM cantilever to measure ultra-light weight masses using a Focused Ion Beam (FIB) deposition technology is demonstrated in this paper. The FIB deposited tungsten was found to contain a significant concentration of gallium from the process. The position of the deposit on the cantilever beam is crucial and is shown to alter significantly the spring constant k and the effective mass of the beam. To illustrate the potential of the technique, a sample of albumin was measured.