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A New Elementary Method for Determining the Tip Radius and Young’s Modulus in AFM Spherical Indentations

Atomic force microscopy (AFM) is a powerful tool for characterizing biological materials at the nanoscale utilizing the AFM nanoindentation method. When testing biological materials, spherical indenters are typically employed to reduce the possibility of damaging the sample. The accuracy of determin...

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Autores principales: Kontomaris, Stylianos Vasileios, Stylianou, Andreas, Chliveros, Georgios, Malamou, Anna
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10536531/
https://www.ncbi.nlm.nih.gov/pubmed/37763878
http://dx.doi.org/10.3390/mi14091716
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author Kontomaris, Stylianos Vasileios
Stylianou, Andreas
Chliveros, Georgios
Malamou, Anna
author_facet Kontomaris, Stylianos Vasileios
Stylianou, Andreas
Chliveros, Georgios
Malamou, Anna
author_sort Kontomaris, Stylianos Vasileios
collection PubMed
description Atomic force microscopy (AFM) is a powerful tool for characterizing biological materials at the nanoscale utilizing the AFM nanoindentation method. When testing biological materials, spherical indenters are typically employed to reduce the possibility of damaging the sample. The accuracy of determining Young’s modulus depends, among other factors, on the calibration of the indenter, i.e., the determination of the tip radius. This paper demonstrates that the tip radius can be approximately calculated using a single force–indentation curve on an unknown, soft sample without performing any additional experimental calibration process. The proposed method is based on plotting a tangent line on the force indentation curve at the maximum indentation depth. Subsequently, using equations that relate the applied force, maximum indentation depth, and the tip radius, the calculation of the tip radius becomes trivial. It is significant to note that the method requires only a single force–indentation curve and does not necessitate knowledge of the sample’s Young’s modulus. Consequently, the determination of both the sample’s Young’s modulus and the tip radius can be performed simultaneously. Thus, the experimental effort is significantly reduced. The method was tested on 80 force–indentation curves obtained on an agarose gel, and the results were accurate.
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spelling pubmed-105365312023-09-29 A New Elementary Method for Determining the Tip Radius and Young’s Modulus in AFM Spherical Indentations Kontomaris, Stylianos Vasileios Stylianou, Andreas Chliveros, Georgios Malamou, Anna Micromachines (Basel) Article Atomic force microscopy (AFM) is a powerful tool for characterizing biological materials at the nanoscale utilizing the AFM nanoindentation method. When testing biological materials, spherical indenters are typically employed to reduce the possibility of damaging the sample. The accuracy of determining Young’s modulus depends, among other factors, on the calibration of the indenter, i.e., the determination of the tip radius. This paper demonstrates that the tip radius can be approximately calculated using a single force–indentation curve on an unknown, soft sample without performing any additional experimental calibration process. The proposed method is based on plotting a tangent line on the force indentation curve at the maximum indentation depth. Subsequently, using equations that relate the applied force, maximum indentation depth, and the tip radius, the calculation of the tip radius becomes trivial. It is significant to note that the method requires only a single force–indentation curve and does not necessitate knowledge of the sample’s Young’s modulus. Consequently, the determination of both the sample’s Young’s modulus and the tip radius can be performed simultaneously. Thus, the experimental effort is significantly reduced. The method was tested on 80 force–indentation curves obtained on an agarose gel, and the results were accurate. MDPI 2023-08-31 /pmc/articles/PMC10536531/ /pubmed/37763878 http://dx.doi.org/10.3390/mi14091716 Text en © 2023 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Kontomaris, Stylianos Vasileios
Stylianou, Andreas
Chliveros, Georgios
Malamou, Anna
A New Elementary Method for Determining the Tip Radius and Young’s Modulus in AFM Spherical Indentations
title A New Elementary Method for Determining the Tip Radius and Young’s Modulus in AFM Spherical Indentations
title_full A New Elementary Method for Determining the Tip Radius and Young’s Modulus in AFM Spherical Indentations
title_fullStr A New Elementary Method for Determining the Tip Radius and Young’s Modulus in AFM Spherical Indentations
title_full_unstemmed A New Elementary Method for Determining the Tip Radius and Young’s Modulus in AFM Spherical Indentations
title_short A New Elementary Method for Determining the Tip Radius and Young’s Modulus in AFM Spherical Indentations
title_sort new elementary method for determining the tip radius and young’s modulus in afm spherical indentations
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10536531/
https://www.ncbi.nlm.nih.gov/pubmed/37763878
http://dx.doi.org/10.3390/mi14091716
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