Comparison between Atomic Force Microscopy and Force Feedback Microscopy static force curves

摘要

Atomic Force Microscopy (AFM) conventional static force curves and ForceFeedback Microscopy (FFM) force curves acquired with the same cantilever at thesolid/air and solid/liquid interfaces are here compared. The capability of theFFM to avoid the jump to contact leads to the complete and direct measurementof the interaction force curve, including the attractive short-range van derWaals and chemical contributions. Attractive force gradients five times higherthan the lever stiffness do not affect the stability of the FFM static feedbackloop. The feedback loop keeps the total force acting on the AFM tip equal tozero, allowing the use of soft cantilevers as force transducers to increase theinstrumental sensitivity. The attractive interactions due to the nucleation ofa capillary bridge at the native oxide silicon/air interface or due to a DLVOinteraction at the mica/deionized water interface have been measured. This setup, suitable for measuring directly and quantitatively interfacial forces, canbe exported to a SFA (Surface Force Apparatus).