  This article describes how a frequency modulation AFM using a hanging fiber
force probe made from a quartz tuning fork provides local measurements on
liquid-liquid interfaces. After detailing the manufacture and calibration of
the force probe, we provide evidence that this AFM is suitable for quantitative
measurements at the interface between two liquids. The repeatability of the
measurements allows a poly-dimethylsiloxane / water moving interface to be
monitored over several hours : the evaporation of a water droplet immersed in
poly-dimethylsiloxane is observed, and its interfacial tension evolution over
time is measured. Deformation of the interface is also observed. These
capabilities, and preliminary results on the interface between two immiscible
liquids, pave the way for interface manipulation and study of complex
fluid-fluid interfaces.
