Numerical study of hydrodynamic forces for AFM operations in liquid
Berthold, Tobias (Universitat Autònoma de Barcelona)
Benstetter, Guenther (Deggendorf Institute of Technology)
Frammelsberger, Werner (Deggendorf Institute of Technology)
Rodríguez Martínez, Rosana (Universitat Autònoma de Barcelona)
Nafría i Maqueda, Montserrat (Universitat Autònoma de Barcelona)

Data:	2017
Resum:	For advanced atomic force microscopy (AFM) investigation of chemical surface modifications or very soft organic sample surfaces, the AFM probe tip needs to be operated in a liquid environment because any attractive or repulsive forces influenced by the measurement environment could obscure molecular forces. Due to fluid properties, the mechanical behavior of the AFM cantilever is influenced by the hydrodynamic drag force due to viscous friction with the liquid. This study provides a numerical model based on computational fluid dynamics (CFD) and investigates the hydrodynamic drag forces for different cantilever geometries and varying fluid conditions for Peakforce Tapping (PFT) in liquids. The developed model was verified by comparing the predicted values with published results of other researchers and the findings confirmed that drag force dependence on tip speed is essentially linear in nature. We observed that triangular cantilever geometry provides significant lower drag forces than rectangular geometry and that short cantilever offers reduced flow resistance. The influence of different liquids such as ultrapure water or an ethanol-water mixture as well as a temperature induced variation of the drag force could be demonstrated. The acting forces are lowest in ultrapure water, whereas with increasing ethanol concentrations the drag forces increase.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	Scanning, Vol. 2017 (2017) , art. 6286595, ISSN 1932-8745

DOI: 10.1155/2017/6286595
PMID: 29109823

12 p, 2.7 MB

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