Acceleration of mixing of two fluids in micro fluidic device by bubbles

Abstract

The Reynolds number of the flow in a micro fluidic device is low. Therefore, it is necessary to promote the mixing by some methods. This paper reports on the research to promote mixing by bubbles generated by an electric heater. A typical flow channel width of a micro fluidic device is 40 to 80μm.This size is not easy to fabricate or to visualize the flow. First, we performed the visualization with the flow channel 10 times as large as the actual device to overcome these difficulties. Two fluids, colored with white and black paints respectively, were mixed in the micro fluidic device. Brightness of the fluid was observed with a CCD microscope. The image was analyzed with a personal computer, and the mixing rate was examined quantitatively.