Kinoshita Haruyuki, Kaneda Shohei, Fujii Teruo, Oshima Marie
Institute of Industrial Science, The University of Tokyo, 4-6-1, Komaba, Meguro-ku, Tokyo, Japan.
Lab Chip. 2007 Mar;7(3):338-46. doi: 10.1039/b617391h. Epub 2006 Dec 22.
This paper presents a micro-flow diagnostic technique, 'high-speed confocal micro-particle image velocimetry (PIV)', and its application to the internal flow measurement of a droplet passing through a microchannel. A confocal micro-PIV system has been successfully constructed wherein a high-speed confocal scanner is combined with the conventional micro-PIV technique. The confocal micro-PIV system enables us to obtain a sequence of sharp and high-contrast cross-sectional particle images at 2000 frames s(-1). This study investigates the confocal depth, which is a significant parameter to determine the out-of-plane measurement resolution in confocal micro-PIV. Using the present confocal micro-PIV system, we can measure velocity distributions of micro-flows in a 228 microm x 171 microm region with a confocal depth of 1.88 microm. We also propose a three-dimensional velocity measurement method based on the confocal micro-PIV and the equation of continuity. This method enables us to measure three velocity components in a three-dimensional domain of micro flows. The confocal micro-PIV system is applied to the internal flow measurement of a droplet. We have measured three-dimensional distributions of three-component velocities of a droplet traveling in a 100 microm (width) x 58 microm (depth) channel. A volumetric velocity distribution inside a droplet is obtained by the confocal micro-PIV and the three-dimensional flow structure inside the droplet is investigated. The measurement results suggest that a three-dimensional and complex circulating flow is formed inside the droplet.
本文介绍了一种微流诊断技术——“高速共聚焦微粒图像测速技术（PIV）”及其在测量微通道内液滴内部流动中的应用。已成功构建了一个共聚焦微PIV系统，其中高速共聚焦扫描仪与传统微PIV技术相结合。该共聚焦微PIV系统使我们能够以2000帧/秒的速度获取一系列清晰且高对比度的横截面粒子图像。本研究探讨了共聚焦深度，这是确定共聚焦微PIV中平面外测量分辨率的一个重要参数。使用当前的共聚焦微PIV系统，我们可以在共聚焦深度为1.88微米的228微米×171微米区域内测量微流的速度分布。我们还提出了一种基于共聚焦微PIV和连续性方程的三维速度测量方法。该方法使我们能够在微流的三维域中测量三个速度分量。共聚焦微PIV系统应用于液滴的内部流动测量。我们测量了在100微米（宽度）×58微米（深度）通道中行进的液滴的三分量速度的三维分布。通过共聚焦微PIV获得了液滴内部的体积速度分布，并研究了液滴内部的三维流动结构。测量结果表明，液滴内部形成了三维复杂循环流。
