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Micro and Nanosystems

Editor-in-Chief

ISSN (Print): 1876-4029
ISSN (Online): 1876-4037

TECHNICAL NOTE

The Truncated Cone Effect in AFM Nanoindentation on Soft Materials

Author(s): Stylianos-Vasileios Kontomaris* and Anna Malamou

Volume 15, Issue 2, 2023

Published on: 09 March, 2023

Page: [153 - 158] Pages: 6

DOI: 10.2174/1876402915666230209140024

Price: $65

Abstract

Background: Atomic Force Microscopy (AFM) nanoindentation is the principal method for the characterization of soft materials at the nanoscale. In most cases, pyramidal tips are used and approximated to perfect cones. However, the extended use of the AFM tip may alter its sharpness.

Objective: In many cases, a truncated cone shape is appropriate for tip modeling. In this technical note, the equation that relates the force with the indentation depth when indenting an elastic halfspace using a truncated cone is derived.

Methods: The nanoindentation equation for a truncated cone tip is derived using the fundamental differential equation that relates the sample’s contact stiffness with Young’s modulus.

Results: When fitting Sneddon’s equation (which is valid for a perfect cone) on data obtained using a truncated cone-shaped AFM tip, the results show a ‘pseudo-softening’ behavior.

Conclusion: The AFM tip's sharpness in nanoindentation experiments is a crucial parameter for obtaining the correct mechanical patterns of unknown samples.

Keywords: Blunt tip, mechanical properties, soft samples, biological materials, softening behavior, Young’s modulus.

Graphical Abstract
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