Volume Illumination for Novel Micro PIV Measurement Technique

微質點速度影像量測技術(MPIV)已經被廣泛的應用在微流體裝置中流場的速度量測上，爲了能夠輕易且有效的找出微流體裝置之中流場的暫態現象，有別傳統螢光量測演算法，本研究建置一個結合高速攝影技術、長焦距顯微影像系統、高功率光放射二極體照明並以非螢光反置影像爲演算法的高頻率微質點速度影像量測技術(HFMPIV)，其量測平面景深係以體積照亮所形成的直接光學景深加以之計算，同時定義有效的對比值將離開量測光學景深未聚焦之粒子影像去除以降低量測信噪比，本方法在微流體裝置量測上將可以達到125μs時間解析以及2.2×2.2m^2的空間解析，實驗結果顯示以高頻率微質點速度影像量測技術(HFMPIV)所得量測值與數值模擬所得結果相當吻合，因此採用高頻微質點速度影像量測法進行微流體裝置中流場的速度量測，將能在不採用螢光技巧的情況下獲得更短的量測時間解析。

關鍵字

高頻率微質點速度影像量測法；爲流體裝置；螢光；時間解析

並列摘要

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.