Mode coupling in a hanging-fiber AFM used as a rheological probe
Université de Lyon, Laboratoire de Physique, École Normale Supérieure de Lyon, CNRS UMR5672 46, Allée d'Italie, 69364 Lyon Cedex 07, France
Received: 10 November 2013
Accepted: 14 May 2014
We analyze the advantages and drawbacks of a method which measures the viscosity of liquids at microscales, using a thin glass fiber fixed on the tip of a cantilever of an ultra-low-noise Atomic Force Microscope (AFM). When the fiber is dipped into a liquid, the dissipation of the cantilever-fiber system, which is linked to the liquid viscosity, can be computed from the power spectral density of the thermal fluctuations of the cantilever deflection. The high sensitivity of the AFM allows us to show the existence and to develop a model of the coupling between the dynamics of the fiber and that of the cantilever. This model, which accurately fits the experimental data, gives also more insights into the dynamics of coupled microdevices in a viscous environment.
PACS: 47.61.Fg – Flows in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS) / 83.85.Jn – Viscosity measurements / 05.40.-a – Fluctuation phenomena, random processes, noise, and Brownian motion
© EPLA, 2014