This paper reports a new technique of micro-resolution Particle Image Velocimetry (PIV). To investigate transient vortices at oil-water interface in a microfluidic device, a high-speed micro-PIV technique was developed by combining a high-speed camera and a continuous wave (CW) laser. The technique was applied to a micro counter-current flow. The micro counter-current flow was an efficient solvent extraction system consisting of water flow and butyl acetate flow. The velocity fields of water in the micro counter-current flow were visualized for a time resolution of 500 μs and a spatial resolution of 2.2 x 2.2 μm. Using the high-speed micro PIV technique, the vortices at the water-butyl acetate interface were captured clearly.
