High Resolution Viscosity Measurement by Thermal Noise Detection

Felipe A. Aguilar Sandoval (1) , Manuel Sepúlveda (1) , Ludovic Bellon (2) , Francisco Melo (1)

1 Departamento de Física
2 Phys-ENS - Laboratoire de Physique de l'ENS Lyon

An interferometric method is implemented in order to accurately assess the thermal fluctuations of a micro-cantilever sensor in liquid environments. The power spectrum density (PSD) of thermal fluctuations together with Sader's model of the cantilever allow for the indirect measurement of the liquid viscosity with good accuracy. The good quality of the deflection signal and the characteristic low noise of the instrument allow for the detection and corrections of drawbacks due to both the cantilever shape irregularities and the uncertainties on the position of the laser spot at the fluctuating end of the cantilever. Variation of viscosity below 0.03 mPa·s was detected with the alternative to achieve measurements with a volume as low as 50 µL.

Mots clés: MEMS; thermal fluctuations; viscosity in liquids

Domaines: Matière Molle [cond-mat.soft]; Instrumentations et Détecteurs [physics.ins-det]

Felipe A. Aguilar Sandoval, Manuel Sepúlveda, Ludovic Bellon, Francisco Melo. High Resolution Viscosity Measurement by Thermal Noise Detection. Sensors, 2015, ⟨10.3390/s151127905⟩. ⟨hal-01226408⟩