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Nathan DeRaymond

Accuracy of AFM Nanoindentation for Probing Cell Mechanics – A Finite Element Approach

Department: Mechanical Engineering and Mechanics
Advisor: Hannah Dailey and Frank Zhang

The purpose of this study was to analyze the accuracy of the Atomic Force Microscopy (AFM) technique for determining cellular elasticity by creating computational models with Finite Element Analysis (FEA). AFM is a widely used technique for measuring the mechanical properties of cells, but inconsistent results are often reported in the literature and between individual cells in a single experiment. Using idealized models of cells, this study examined some sources of experimental variation. The FEA approach provides control over the factors that affect the results of AFM. In these models, several parameters were varied, including: cell height, cell stiffness, and the AFM tip geometry (spherical bead or cone). The results showed that short cells appear to be stiffer than tall cells, due to the presence of the rigid boundary where the cell attaches to the substrate. The models also predicted that using a conical AFM tip leads to an over-prediction of cell stiffness compared to using a spherical tip. Overall, this project demonstrated some sources of error in the analysis of AFM data and helped to provide guidance to use only spherical AFM tips for increased measurement accuracy.

About Nathan DeRaymond:
Nathan DeRaymond is a junior studying mechanical engineering and physics through the IDEAS program. During the summer of 2016, he worked in the lab under Professor’s Hannah Dailey and Frank Zhang in the Biodynamics Summer Institute. He studied the method of Atomic Force Microscopy by creating computational simulations using finite element analysis. In his free time, Nathan enjoys drumming and is a member of the Marching 97.