  Atomic Force Microscopy (AFM) conventional static force curves and Force
Feedback Microscopy (FFM) force curves acquired with the same cantilever at the
solid/air and solid/liquid interfaces are here compared. The capability of the
FFM to avoid the jump to contact leads to the complete and direct measurement
of the interaction force curve, including the attractive short-range van der
Waals and chemical contributions. Attractive force gradients five times higher
than the lever stiffness do not affect the stability of the FFM static feedback
loop. The feedback loop keeps the total force acting on the AFM tip equal to
zero, allowing the use of soft cantilevers as force transducers to increase the
instrumental sensitivity. The attractive interactions due to the nucleation of
a capillary bridge at the native oxide silicon/air interface or due to a DLVO
interaction at the mica/deionized water interface have been measured. This set
up, suitable for measuring directly and quantitatively interfacial forces, can
be exported to a SFA (Surface Force Apparatus).
