Volume Illumination for Novel Micro PIV Measurement Technique

Abstract

The micro particle image velocimetry (MPIV) technique has been widely adopted for the measurements of velocity field in microfluidic devices. To simply the investigation of the transient phenomena in a usual biological microfluidic device, this study, a novel high frequency MPIV technique without fluorescence, was developed by combining a high-speed CMOS camera, a long working distance zoom microscope, a high power LED along with reversed image algorithm. The depth of the measurement plane is defined by the focusing characteristics of the probing optics through volume illumination. With efficacious contrast base, the unfocused particle images, which are out of the measurement plane, create background noise that decreases the single-to-noise ratio of the particle image fields. The velocity fields of fluid in the micro device were visualized for a time resolution of 125μs and a spatial resolution of 2.2×2.2m^2. The result shows that the numerical predictions are very similar to the measurement of high frequency MPIV inside the micro flow device. Consequently, by using the novel MPIV technique, the time resolution can be abbreviated and the tracing particles require no decorating with fluorescing.