Mass and stiffness measurement using a multi-modal analysis

Master thesis (2017)

Authors

L.M.F.R. Hauzer Mechanical Engineering

Contributors

P.G. Steeneken (supervisor 2)
F. Alijani (supervisor 1)
M.K. Ghatkesar (supervisor 1)
P. Belardinelli (coach)
Faculty
Mechanical Engineering
Copyright: © 2017 Lili Maxime Hauzer
Measurement Mass Stiffness Microcantilever resonator Two-photon polymerization Multi-modal Microscale
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Published Date

11-12-2017

Language

English

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Faculty

Mechanical Engineering

Abstract

Biomechanics of cells have been identified as an important factor relating to their functionalities. Consequently, the need for sensitive measurement methods for mechanical analysis on the nano- and microscale is high. Micro-cantilever resonators can have a large impact in material determination at the nanoscale. When adding a material, the resulting shift in resonance frequency is associated with its mass and stiffness properties. The goal of this project is to exploit the contribution of higher flexural modes on the determination of both the density and Young's modulus of an added polymer on a micro-cantilever.
The identification of mass and stiffness is, in this thesis, restricted to the deposition of a two-photon polymerized layer on micro-cantilevers. A polymeric material is used, since cells are complex systems with viscoelastic properties, where polymers are less complex and mimic biological matter very well. Two configurations are investigated: an added polymer near the tip of the cantilever and a polymeric layer near the base of the beam. Experimentally and theoretically derived multi-modal analysis are linked, to decouple the mass and stiffness properties.
The added polymeric layer affects the resonance frequency of the system, which is found to be location and mode related. Decoupling of the mass and stiffness properties based on the modes with the largest frequency shift, lead to different outcomes compared to considering modes with the largest deflection and curvature at a specific location. The use of higher modes does affect the outcomes of the decoupling of mass and stiffness. Whether it leads to an increase on accuracy is yet elusive.