Quantitative comparison of three calibration techniques for the lateral force microscope

Abstract

The quantitative use of atomic force microscopes in lateral mode for friction measurements has been limited by uncertainty about reliable calibration techniques. This article describes a comparison of three methods that have been proposed for the calibration of the lateral sensitivity of atomic force microscopes: (a) one based on movement of the photodiode assembly, (b) one based on the slope of the friction-loop while the contacting surfaces are in static contact, and (c) one based on a comparison of the lateral force signal on a surface with changing slopes of known orientation. All three methods gave comparable results thereby confirming their robust nature, and also confirming the validity of atomic force microscope methods for lateral force measurement. However, (b) indicated that for the commercial instrument used here, the lateral signal sensitivity is load dependent. A simple extension to (a) revealed the nature of this dependence: a misalignment of the four-quadrant photodiode detection system with respect to the alignment of the reflected beam path resulting in a coupling of the normal and lateral signals. The result is that the lateral signal does not scale directly with friction, requiring that for friction versus applied load studies, lateral signal calibration be performed across the full range of applied loads of interest. To a greater or lesser extent, this shortcoming will be evident in a wide range of commercial instruments. All three methods studied here have special advantages: (a) provides the most complete information about the detector response, (b) provides a calibration method when friction characteristics of colloid probes of a wide range of possible materials are of interest, and (c) has the advantage of also providing information about the state of the tip geometry.

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

“…Regarding the problem of ͑A͒, since the calibration relies on frictional slip processes over sharp edges of the wedge, the tip can be subjected to wear damage during the calibration process as pointed out by Cain et al 15 Also the critical friction forces at the onset of slip have stochastic features and it is difficult to read such forces accurately. With regard to ͑B͒, it is convenient to use a difference form of ͑5͒, and the corresponding comprehensive analysis of an AFM response in the wedge method is summarized in Appendix A.…”

Piezoelectric Tensor of Collagen Fibrils Determined at the Nanoscale

“…For a comprehensive discussion of lateral InvOLS calibration, see these reviews. [33][34][35][36][37] Furthermore, it is important to point out that convergence of local PFM and macroscopic piezoelectric measurements is unlikely due to the highly inhomogeneous electric field at the tip and corresponding locally confined deformation, which might be affected by sample-induced clamping. Thus, the measured response is sensitive not only to piezoelectric, but also elastic moduli, and dielectric constants.…”

Atomic force microscopy and direct surface force measurements (IUPAC Technical Report)

“…Perhaps the most promising experimental approach is that of Sader et al [11], where the spring constant can be unambiguously obtained from a measurement of the resonant frequencies of torsional and flexural vibrations of the cantilever in air. Numerous other approaches have been suggested, with varying degrees of success and applicability to the colloid probe technique, and have been compared and discussed in recent reviews [66,67].…”