OS06W0415 Subtle non-newtonian property measurement of micro fluids using squeeze flow rheometry

Abstract

Dynamics of micro fluidic systems (MFS) is dominated by a fully coupled fluid-structure system. Hence, a subtle non-Newtonian property of a operation fluid often affects the system erformance. For measurements of such micro fluid properties, a squeeze flow rheometry is suitable, because a flow scale and a flow field which a test fluid undergoes are similar to those of the micro fluidic systems. Al-though the squeeze flow rheometry has a outstanding potential, it also has some intrinsic problems which come from the principle of measurements as well as the incompleteness of the instrument. In this paper, we propose a novel data manipulation method for a squeeze flow rheometry, which compensates those defects of the squeeze flow rheometer, and applying it to a instrument, demonstrate measurements of subtle non-Newtonian behavior: shear thinning and Thixotropy of dilute suspensions of monodisperse acrylic particles. In these measurements, a small Thixotropic viscosity change was detected in startup transition related to the reversible order-disorder transition of a colloidal structure. This measurement method can give indispensable information and means for investigation of non-Newtonian fluid dynamics and for developments of the MFS devices.