Summary: Measurement of friction coefficients with the atomic
Phil Attard1, Johanna Stiernstedt2 and Mark W. Rutland2
School of Chemistry F11, University of Sydney, NSW 2006 Australia.
Department of Surface Chemistry, Royal Institute of Technology, SE-100 44 Stockholm,
Sweden and Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden
Abstract. A new axial method for measuring the friction coefficient with the atomic force
microscope is given. This axial method requires no calibration steps and is performed
simultaneously with a normal force measurement by measuring the difference between the
constant compliance slopes of the extend and retract force curves. The algorithm can be applied
retrospectively to extract the friction coefficient from preexisting force measurements. Results
are in quantitative agreement with the more established lateral method. The method can be
used for both tipped cantilevers and for attached spherical probes.
The atomic force microscope, (AFM), has been extensively used in lateral scanning mode to
measure or to image friction qualitatively. Comparatively fewer quantitative measurements have
been made due to the difficulty in calibrating the torsional spring constant of the cantilever and