Development of 3-dimensional PTV system in microchannel

With the wide development of microfluidic applications, the importance of the flow field analysis in a microchannel is growing. The most common technique to visualize flow in a microchannel is PIV, in which only 2-dimensinal (2-D) flow can be observed. However, complicated 3-dimensional (3-D) structures for microfluidic systems are widely developing, and the necessity of measurements for 3- dimensional flow is now increasing. In this paper, we developed a 3-dimensional PTV (Particle Tracking Velocimetry) system for observing flow in a 100 μm x 55 μm microchannel. There are several crucial points to developing a micro-3D-PTV system, such as the requirement for lens, darkness of images and calibration method. Using two lenses of long working distance and focusing length and high-speed cameras, we successfully obtained 2 different anglular images with 200 frame/s. A microchannel was fablicated from PDMS, and distilled water with 5μm diameter fluorescent particles was used as the test liquid. Although the obtained images were not so clear, stereoscopic observation was successively carried out, and 3-D particle motions in a microchannel were calculated.