Reduction of the cantilever hydrodynamic damping near a surface by ion-beam milling

In this work, we evaluate the influence of the cantilever width on the hydrodynamic drag force. To do so, we present an experimental analysis of the thermal motion in air and liquid of a commercial and modified by focused ion-beam (FIB) milling silicon nitride cantilevers. From the thermal noise spectrum, we extract the damping for different cantilever-sample distances. We show that the hydrodynamic force due to the drag can be reduced by almost an order of magnitude when reducing the cantilever width. With the FIB modification (milling) one can still use conventional atomic force microscope heads with a significant reduction of the hydrodynamic forces.