Published online by Cambridge University Press: 08 August 2002
The atomic force microscope (AFM) has previously been applied to the measurement of surfaceforces (including adhesion and friction) and to the investigation of material properties, such as hardness. Herewe describe the modification of a commercial AFM that enables the stiffness of interaction between surfacesto be measured concurrently with the surface forces. The stiffness is described by the rheological phasedifference between the response of the AFM tip to a driving oscillation of the substrate. We present theinteraction between silica surfaces bearing adsorbed polymer, however, the principles could be applied to a widevariety of materials including biological samples.