Adhesive force distribution on microstructures investigated by an atomic force microscope

The adhesive force distribution on microstructures is measured by an atomic force microscope (AFM). The AFM probe used in the experiments consists of a micromachined cantilever and a micromachined sharp tip. The adhesive force (capillary force) acting between a sample surface and the AFM tip is determined from a measured force curve (probe deflection as a function of the distance between sample surface and AFM tip). By repeating the force curve measurement, the adhesive force distribution is obtained. In the same area, the surface topography is also measured by the AFM. When a flat glass substrate (roughness less than 10 nm) is used as a sample, the adhesive force distribution is structureless. However, the adhesive force is influenced considerably by the surface topography when a grating sample and a latex sample are used. The relation between the topography and the adhesive force distribution, which is relevant to the designing of micromechanical structures, is discussed.