THE INTERACTION BETWEEN MICROMETER-SIZE PARTICLES AND FLAT SUBSTRATES- A QUANTITATIVE STUDY OF JUMP-TO-CONTACT

The interaction force acting on an individual micrometer-size polystyr ene particle near a flat, electrically conducting substrate has been m easured by attaching the particle to an atomic force microscope cantil ever. From the spatial dependence of the interaction force, the equati ons of motion governing a particle near the substrate can be determine d. These considerations allow a prediction of the jump-to-contact dist ance of the particle as it approaches the substrate. This distance is measured as a function of particle radius and compared with prediction s bused on the relevant interaction force models.