Measuring creep response of soft samples by magnetic force microscopy
|MagneticAFM__ReCreepResponseSofSamples_Physics_Yango_Achu_Revised edition_07 Feb2023.pdf||53.15 MB||Adobe PDF||View/Open|
In this work we propose a setup for applying large controlled external magnetic fields in magnet on force transducers by Atomic Force Microscopy. We have measured the creep response of soft gels and cells after applying a step in loading force with atomic force microscopy (AFM). By analysing the creep response data using the standard linear solid model, we can quantify the viscous and elastic properties of these soft samples independently. Cells, in comparison with gels of similar softness, are much more viscous, as has been qualitatively observed in conventional force curve data before. Here, we quantify the spring constant and the viscous damping coefficient from the creep response data. We propose two different modes for applying a force step: (1) indirectly by increasing the sample height or (2) directly by employing magnetic cantilevers. Both lead to similar results, whereas the latter seems to be better defined since it resembles closely a constant strain mode. The former is easier to implement in most instruments, and thus may be preferable from a practical point of view. Creep analysis by step response is much more appropriate to analyse the viscoelastic response of soft samples like cells than the usually used force curve analysis.
|Description:||This publication is a revised version of the dissertation of the same title defended at the University of Bremen in February 2023.||Keywords:||Temperature; Soft samples; Diseased cells; Thermal fluctuations; Visous properties; Elastic properties; External magnetic fields; Coils; Quantisation; Entropy; Standard linear solid model; Atomic Force Microscopy; Conventional force curve; Direct step AFM; Enthalphy; Constant strain mode; Magnetic particles; Viscous damping coefficient of friction; Soft spring AFM cantilevers; Proteins; Surface force microscope; Hamaker constant; Newtonian mechanics; Cytosol; Cytoskeleton; Viscoelastic properties; Relaxation time constants; Magnetic step response; Z-step response; Load step unload step; Magnetic sensitivity; Fourier transform; Contact mode AFM; Thermal motion; Biological sample interaction; Relaxation||Issue Date:||2023||Secondary publication:||no||DOI:||10.26092/elib/2569||URN:||urn:nbn:de:gbv:46-elib73037||Institution:||Universität Bremen||Faculty:||Fachbereich 01: Physik/Elektrotechnik (FB 01)|
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checked on Nov 28, 2023
checked on Nov 28, 2023
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