Quantitative mechanical analysis of indentations on layered, soft elastic materials

Bryant L. Doss, Kiarash Rahmani Eliato, Keng hui Lin, Robert Ros

Research output: Contribution to journalArticle

Abstract

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. In this work, we numerically calculated force-indentation curves onto two-layered elastic materials using an analytic model. We found that the effect of the underlying substrate can be quantitatively predicted by the mismatch in elastic moduli and the homogeneous-case contact radius relative to the layer height for all tested probe geometries. The effect is analogous to one-dimensional Hookean springs in series and was phenomenologically modeled to obtain an approximate closed-form equation for the indentation force onto a two-layered elastic material which is accurate for up to two orders of magnitude mismatch in Young's modulus when the contact radius is less than the layer height. We performed finite element analysis simulations to verify the model and AFM microindentation experiments and macroindentation experiments to demonstrate its ability to deconvolute the Young's modulus of each layer. The model can be broadly used to quantify and serve as a guideline for designing and interpreting indentation experiments into mechanically heterogeneous samples.

Original languageEnglish (US)
Pages (from-to)1776-1784
Number of pages9
JournalSoft Matter
Volume15
Issue number8
DOIs
StatePublished - Jan 1 2019

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indentation
Indentation
modulus of elasticity
Elastic moduli
Atomic force microscopy
Experiments
atomic force microscopy
radii
microhardness
Mechanics
Finite element method
Geometry
probes
Substrates
curves
geometry
cells
simulation

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics

Cite this

Quantitative mechanical analysis of indentations on layered, soft elastic materials. / Doss, Bryant L.; Rahmani Eliato, Kiarash; Lin, Keng hui; Ros, Robert.

In: Soft Matter, Vol. 15, No. 8, 01.01.2019, p. 1776-1784.

Research output: Contribution to journalArticle

Doss, Bryant L. ; Rahmani Eliato, Kiarash ; Lin, Keng hui ; Ros, Robert. / Quantitative mechanical analysis of indentations on layered, soft elastic materials. In: Soft Matter. 2019 ; Vol. 15, No. 8. pp. 1776-1784.
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