Lock-in technique for measuring friction on a nanometer scale

Abstract

A method for measuring friction forces on a nanometer scale is described. This method combines a lock-in technique with scanning force and friction microscopy. Essentially, a lock-in amplifier is used to determine the amplitude of the friction loop, which is measured at high frequency. To demonstrate the capability of this method, the dependence of the friction force with normal load is measured and a two dimensional image is presented.