Parametrization of atomic force microscopy tip shape models for quantitative nanomechanical measurements

Abstract

The uncertainty of the shape of the tip is a significant source of error in atomic force microscopy (AFM) based quantitative nanomechanical measurements. Using transmission electron microscopy, scanning electron microscopy, or tip reconstruction images, it is possible to parametrize the models of real AFM tips, which can be used in quantitative nanomechanical measurements. These measurements use algorithms described in this article that extend classical elastic, plastic, and adhesive models of contact mechanics. Algorithms are applicable to the tips of arbitrary axisymmetric shapes. Several models of AFM tip have been utilized. The goal of tip model parameterization is to develop AFM tip-independent quantitative mechanical measurements at the nanometer scale. Experimental results demonstrate independence of the AFM measurements from tips and their closeness to bulk measurements where available. In this article the authors show the correspondence between microtensile, nanoindentation, and AFM based indentation for measuring the modulus of a spin on low-k dielectric polymer thin film. These results provide a confidence that with the described procedures AFM can be used for reliable quantitative nanomechanical measurements.

Glyphosate-induced stiffening of HaCaT keratinocytes, a Peak Force Tapping study on living cells

“…Because this model is not native to the AFM, for each image, a high speed data capture (HSDC) (5400 points) of the force curve signal was obtained. Creating multiple HSDC files, enabled the raw force curves to be exported and post-processed by using a custom program, Rainbow (Belikov et al, 2009), which gives the user the possibility to apply several different models, including Sneddon, to extract Young's modulus. The force curves are captured on a representative part of the image where only cells are present rather than the scaffold.…”

Modeling and measurements in Atomic Force Microscopy Resonance Modes

“…So far, the quantitative measurements were primarily based on extraction of elastic modulus and work of adhesion from the Force-vs-Deformation curve. This curve was calculated from the experimental Deflection-vs-Distance curve [2] collected in the contact mode or in the nonresonance oscillatory modes. In the AFM resonance modes, Amplitude Modulation (AM) [3] and Frequency Modulation (FM) [4] respectively, the amplitude damping and frequency shift of the interacting probe (cantilever with the tip) near its resonance is employed for imaging.…”

Expression of Tumor Suppressors PTEN and TP53 in Isogenic Glioblastoma U-251MG Cells Affects Cellular Mechanical Properties — An AFM-Based Quantitative Investigation

“…The deflection sensitivity was calibrated on a non-compliant part of the sample and the spring constant by using a thermal tune sweep, and found to be between 0.1 and 0.3 N/m. The Young's modulus was extracted by using a Sneddon fit [38,39] which takes the deformation induced by the indenter into account, considering the AFM tip as an infinite cone, and is well adapted to biological samples. The principle of force curve processing was previously described [36].…”