Theory of amplitude modulated electrostatic force microscopy for dielectric measurements in liquids at MHz frequencies.
A theoretical analysis of amplitude modulated electrostatic force microscopy (AM-EFM) in liquid media at MHz frequencies, based on a simple tip-sample parallel plate model, is presented. The model qualitatively explains the main features of AM-EFM in liquid media and provides a simple explanation of how the measured electric forces are affected by: the frequency of the applied voltage, the tip-sample distance, the ionic concentration, the relative dielectric constant of the solution, and the relative dielectric constant and thickness of the sample. These results provide a simple framework for the design of AM-EFM measurements for localized dielectric characterization in liquid media.
Institut de Bioenginyeria de Catalunya (IBEC), C/Baldiri i Reixac 15-21, E-08028 Barcelona, Spain. Departament d'Electrònica, Universitat de Barcelona, C/Martí i Franquès 1, E-08028 Barcelona, Spain.
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Gramse
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Edwards
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Fumagalli
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Gomila