Combined polarized Raman and atomic force microscopy: In situ study of point defects and mechanical properties in individual ZnO nanobelts

Atomic force microscopy (AFM) can determine mechanical properties, associated with surface topography and structure, of a material at the nanoscale. Force–indentation curves that depict the deformation of a target specimen as a function of an applied force are widely used to determine the elastic modulus of a material based on a contact model. However, a hysteresis may arise due to friction between the AFM tip and a specimen. Consequently, the normal force detected using a photodetector during extension and retraction could be underestimated and overestimated, respectively, and the extension/retraction data could result in a significant difference in the elastic modulus measurement result. In this study, elastic modulus and friction coefficient values were determined based on an in situ theoretical model that compensated for the effect of friction on force–indentation data. It validated the proposed model using three different polymer specimens and colloidal-tipped probes for the force–indentation curve and friction loop measurements. This research could contribute to the accurate measurement of mechanical properties using AFM by enhancing the interpretation of force–indentation curves with friction-induced hysteresis. Furthermore, the proposed approach may be useful for analyzing in situ relationships between mechanical and frictional properties from a fundamental tribological perspective.

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In-Situ Determination of the Mechanical Properties of Gliding or Non-Motile Bacteria by Atomic Force Microscopy under Physiological Conditions without Immobilization

PLoS ONE ◽

10.1371/journal.pone.0061663 ◽

2013 ◽

Vol 8 (4) ◽

pp. e61663 ◽

Cited By ~ 19

Author(s):

Samia Dhahri ◽

Michel Ramonda ◽

Christian Marlière

Keyword(s):

Mechanical Properties ◽

Atomic Force Microscopy ◽

Force Microscopy ◽

Physiological Conditions ◽

Atomic Force ◽

Motile Bacteria

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The Inhomogeneous Mechanical Properties of the Pericellular Matrix of Articular Cartilage Measured In Situ by Atomic Force Microscopy

ASME 2009 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2009-206403 ◽

2009 ◽

Author(s):

Rebecca E. Wilusz ◽

Eric M. Darling ◽

Michael P. Bolognesi ◽

Stefan Zauscher ◽

Farshid Guilak

Keyword(s):

Mechanical Properties ◽

Atomic Force Microscopy ◽

Articular Cartilage ◽

Biomechanical Properties ◽

Human Articular Cartilage ◽

Pericellular Matrix ◽

Force Microscopy ◽

Narrow Region ◽

Atomic Force

Articular cartilage is the connective tissue that lines the articulating surfaces of diarthrodial joints, providing a low-friction, load-bearing surface during joint motion. Articular cartilage comprises of a single cell type, the chondrocyte, embedded within an extensive extracellular matrix (ECM). Each chondrocyte is surrounded by a narrow region called the pericellular matrix (PCM) that is distinct from the ECM in both its biochemical composition [1] and biomechanical properties [2]. While multiple techniques have been used to measure the mechanical properties of the PCM, including micropipette aspiration of isolated chondrons [2], these studies required mechanical or enzymatic extraction of the chondrocyte and surrounding PCM (i.e., the “chondron” [1]) from the cartilage, and the influence of this isolation process on PCM properties is unknown. Atomic force microscopy (AFM) provides a high resolution form of nano- and microindentation approaches that can be used to measure local mechanical properties in situ [3,4]. The objective of this study was to use AFM to quantify the biomechanical properties of the ECM and PCM of human articular cartilage in situ.

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