Confocal Micro-PIV Measurement of Micro- Multiphase Flow in The Microfluidic Devices

Abstract

This paper presents a micro-multiphase flow measurement technique using ‘multicolour confocal micro-particle image velocimetry (PIV)’ by wavelength separation technique. The present system can measure the dynamic interaction between flows in two different phases, such as liquid-liquid or solid-liquid, simultaneously and separately. The system has high temporal resolution up to 2000 frames per second, and high spatial resolution up to 0.116 μm/pixel in plane and 0.58μm out of plane, which is enough to resolve cell size measurement target.
　In this paper, three measurement demonstrations are shown. There are flow inside and outside of moving microdroplet, droplet formation at T-shaped junction and red blood cells (RBCs) dispersed flow. The droplet is studied as a liquid-liquid multiphase flow using immiscible two liquids of oil and water. This study clarifies not only three-dimensional flow structure using continuity equation-assisted method, but also shear force between its interface. These informations are necessary for estimation of mixing effect using circulation in the droplet and discussion on droplet formation mechanism.
　The measurement of RBCs mixed flow requires more due to its unsteadiness and randomness derives from characteristics of live cells. Our developed ‘Target-tracking system’ can measure one individual cell for long time under the high-magnification measurement condition. Finally the tank-treading motion of RBC and the surrounding flow structure simultaneously for the investigation of specific behavior of RBC.