Langmuir, Vol.18, No.21, 7798-7803, 2002
Controlled translational manipulation of small latex spheres by dynamic force microscopy
We report on the application of a home-built scanning force microscope for translation and in-plane rotation of nanometer-sized latex spheres by dynamic surface modification (DSM). This technique is based on the increment of the amplitude of the oscillating voltage applied at the dither piezo that drives the cantilever vibrations in the dynamic mode of scanning force microscopy. Thus, it is easily possible to switch between the imaging mode and DSM mode, enabling the direct manipulation of nanostructures under ambient conditions with high precision. The main advantage of our technique compared to earlier methods is that it operates with an active feedback loop, allowing a steady manipulation of nanostructures independent of the surface corrugation or sample tilt. Such controlled translations of latex spheres enable us in addition to study their properties regarding friction, adhesion, and cohesion. By translating latex spheres of different sizes (radii between 50 and 110 nm), it was found that the force needed to move a particle depends on its dimensions. Finally, the lateral translation of an intentionally marked sphere gives evidence that sliding is preferred over rolling.