scholarly journals Linear Viscoelasticity: Review of Theory and Applications in Atomic Force Microscopy

2021 ◽  
Vol 2 (1) ◽  
pp. 156-179
Author(s):  
Marshall McCraw ◽  
◽  
Berkin Uluutku ◽  
Santiago Solares ◽  
◽  
...  

Recently, much research has been performed involving the mechanical analysis of biological and polymeric samples with the use of Atomic Force Microscopy (AFM). Such materials require careful treatments which consider the rate-dependence of their viscoelastic response. Here, we review the fundamental theories of linear viscoelasticity, as well as their application to the analysis of AFM spectroscopy data. An outline of general viscoelastic mechanical phenomena is initially given, followed by a brief outline of AFM techniques. Then, an extensive outline of linear viscoelastic material models, as well as contact mechanics descriptions of AFM systems, are presented.

Soft Matter ◽  
2019 ◽  
Vol 15 (8) ◽  
pp. 1776-1784 ◽  
Author(s):  
Bryant L. Doss ◽  
Kiarash Rahmani Eliato ◽  
Keng-hui Lin ◽  
Robert Ros

Atomic force microscopy (AFM) is becoming an increasingly popular method for studying cell mechanics, however the existing analysis tools for determining the elastic modulus from indentation experiments are unable to quantitatively account for mechanical heterogeneity commonly found in biological samples.


Friction ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 415-428
Author(s):  
José Enrique Martín-Alfonso ◽  
María José Martín-Alfonso ◽  
Concepción Valencia ◽  
María Teresa Cuberes

AbstractThis study investigates the development of novel montmorillonite/castor oil blends to formulate sustainable lubricating greases to promote the replacement of petrochemicals industry-derived materials by substances obtained from renewable sources. Specifically, the effect of the thickener concentration on the rheological, chemical, thermal, tribological properties, and atomic force microscopy (AFM) microstructure of these systems were studied. The results showed that the C20A nanoclay content could be used to modulate the viscosity values, the linear viscoelastic functions, and tribological properties of these montmorillonite dispersions. In general, these gel-like dispersions exhibited remarkable lubricant properties; the samples showed values of the friction coefficient and wear scars similar or lower than those obtained with model bentonite grease.


2020 ◽  
Vol 11 ◽  
pp. 1409-1418
Author(s):  
Enrique A López-Guerra ◽  
Santiago D Solares

Atomic force microscopy (AFM) is a widely use technique to acquire topographical, mechanical, or electromagnetic properties of surfaces, as well as to induce surface modifications at the micrometer and nanometer scale. Viscoelastic materials, examples of which include many polymers and biological materials, are an important class of systems, the mechanical response of which depends on the rate of application of the stresses imparted by the AFM tip. The mechanical response of these materials thus depends strongly on the frequency at which the characterization is performed, so much so that important aspects of behavior may be missed if one chooses an arbitrary characterization frequency regardless of the materials properties. In this paper we present a linear viscoelastic analysis of intermittent-contact, nearly resonant dynamic AFM characterization of such materials, considering the possibility of multiple characteristic times. We describe some of the intricacies observed in their mechanical response and alert the reader about situations where mischaracterization may occur as a result of probing the material at frequency ranges or with probes that preclude observation of its viscoelastic behavior. While we do not offer a solution to the formidable problem of inverting the frequency-dependent viscoelastic behavior of a material from dynamic AFM observables, we suggest that a partial solution is offered by recently developed quasi-static force–distance characterization techniques, which incorporate viscoelastic models with multiple characteristic times and can help inform dynamic AFM characterization.


Soft Matter ◽  
2015 ◽  
Vol 11 (14) ◽  
pp. 2857-2865 ◽  
Author(s):  
Jianyong Huang ◽  
Lucinda J. Camras ◽  
Fan Yuan

We developed a method to quantify the initial Young's modulus of rat trabecular meshwork (TM) in situ, based on atomic force microscopy (AFM).


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