Yango, AchuAchuYango2023-10-192023-10-192023https://media.suub.uni-bremen.de/handle/elib/730310.26092/elib/2569This publication is a revised version of the dissertation of the same title defended at the University of Bremen in February 2023.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.enCC BY 4.0 (Attribution)https://creativecommons.org/licenses/by/4.0/TemperatureSoft samplesDiseased cellsThermal fluctuationsVisous propertiesElastic propertiesExternal magnetic fieldsCoilsQuantisationEntropyStandard linear solid modelAtomic Force MicroscopyConventional force curveDirect step AFMEnthalphyConstant strain modeMagnetic particlesViscous damping coefficient of frictionSoft spring AFM cantileversProteinsSurface force microscopeHamaker constantNewtonian mechanicsCytosolCytoskeletonViscoelastic propertiesRelaxation time constantsMagnetic step responseZ-step responseLoad step unload stepMagnetic sensitivityFourier transformContact mode AFMThermal motionBiological sample interactionRelaxation530urn:nbn:de:gbv:46-elib73037