Friction effects in the deflection of atomic force microscope cantilevers

Abstract

The conventional deflection-mode atomic force microscope operates by optically monitoring the slope near the end of a microcantilever in contact with the sample surface. This signal is usually interpreted as a measure of height change. Lateral forces from friction, surface geometry, or inclination of the cantilever to the surface also affect the slope due to cantilever buckling. We calculate the deflection of a hollow triangular model cantilever subject to both lateral and normal forces. The measured response of the servo circuit to an inclined, loaded cantilever is then determined. This shows (1) errors are always present in height measurements of structures on inhomogeneous surfaces; (2) the sensitivity to buckling can be reduced by repositioning the laser; (3) friction measurements can be accurately made by scanning in two directions and applying the proper calibration.

Contact AFM on soft surfaces: Elasticity and friction effects

“…It is clear from this figure that there exist two regions separated by a abrupt transition at about 700 nm. This behaviour is rather similar to the stick-slip motion , "stiction effect", observed in reference [12] when the x position of the sample is modulated under the tip when scanning. We observed that the transition presents an hysteretic behaviour.…”

“…The difference in piezo height between the two scanning directions along the cantilever direction has been shown to be representative of the longitudinal force exerted on the tip [1,2]. Quantitative analysis of friction depends on the position of the laser beam on the cantilever and there is no perfect linearity of the signal on the tangential forces [12]. However, for the purpose of the present analysis and on a qualitative basis, it is sufficient to understand the différence between the heights in both 'directions as being primarily due to friction.…”

Lateral force calibration of an atomic force microscope with a diamagnetic levitation spring system

“…For example, the lateral force constant ␣ l is comprised of a deformation characteristic , an intermediate transducer characteristic ␤ l , and a structural geometry characteristic H of the cantilever-tip assembly, as shown in ͑6͒. So far, any existing technique for calibrating the force constants could either be characterized as an indirect method of calibration [8][9][10][11][12] or as a semidirect method of calibration. 4,7 The wedge method 4 is one such semidirect calibration method, because we have to evaluate separately some geometric variables, in general, for 0, although we do not have to assess the torsional spring constant and the angle sensitivity constant individually.…”

Influence of spring stiffness and anisotropy on stick-slip atomic force microscopy imaging

“…However, the three translational degrees of freedom of the scanning probe often account for an unwanted mix of frictional and topographic information. [1][2][3][4] This mixing is influenced by the type of detection that is used and is most prominent with optical lever detection. Another aspect is the influence of the scanning configuration or system itself.…”