Quantitative assessment of sample stiffness and sliding friction from force curves in atomic force microscopy

Journal Article · Mon Feb 15 04:00:00 EST 2010 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3284957· OSTI ID:21476148

Pratt, Jon R; Shaw, Gordon A ^[1]; Kumanchik, Lee ^[2]; Burnham, Nancy A ^[3]

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1. National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
2. Department of Mechanical Engineering, University of Florida, Gainesville, Florida 32611 (United States)
3. Department of Physics, Worcester Polytechnic Institute, Worcester, Massachusetts 01609-2280 (United States)

It has long been recognized that the angular deflection of an atomic force microscope (AFM) cantilever under ''normal'' loading conditions can be profoundly influenced by the friction between the tip and the surface. It is shown here that a remarkably quantifiable hysteresis occurs in the slope of loading curves whenever the normal flexural stiffness of the AFM cantilever is greater than that of the sample. This situation arises naturally in cantilever-on-cantilever calibration, but also when trying to measure the stiffness of nanomechanical devices or test structures, or when probing any type of surface or structure that is much more compliant along the surface normal than in transverse directions. Expressions and techniques for evaluating the coefficient of sliding friction between the cantilever tip and sample from normal force curves, as well as relations for determining the stiffness of a mechanically compliant specimen are presented. The model is experimentally supported by the results of cantilever-on-cantilever spring constant calibrations. The cantilever spring constants determined here agree with the values determined using the NIST electrostatic force balance within the limits of the largest uncertainty component, which had a relative value of less than 2.5%. This points the way for quantitative testing of micromechanical and nanomechanical components, more accurate calibration of AFM force, and provides nanotribologists access to information about contact friction from normal force curves.

• OSTI ID: 21476148
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 4 Vol. 107; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ATOMIC FORCE MICROSCOPY
CALIBRATION
ELASTICITY
ELECTROSTATICS
FLEXIBILITY
FRICTION
HYSTERESIS
LOADING
MATERIALS HANDLING
MECHANICAL PROPERTIES
MICROSCOPY
NANOSTRUCTURES
SLIDING FRICTION
SURFACES
TENSILE PROPERTIES
TESTING
TRIBOLOGY