對微奈米粒子進行排列或分離的技術，已廣泛運用於化學加工、食品檢測、生醫工程等領域來進行分析，相對於傳統方式因有儀器設備昂貴、分析時間冗長、分離步驟繁雜等問題，聲輻射力則具備根據粒子的大小、密度、壓縮比等性質來進行區分的特性，不需預先在粒子上做任何處理，因此可廣泛使用在任何粒子上，而利用SSAW裝置可控制粒子到達壓力節點或反壓節點，以達到粒子分離及聚焦的效果。
　　當使用PDMS流道時，會產生所謂的側壁效應(sidewall effect)，亦即流道側壁會形成節點，致使粒子除了聚焦於已預訂的節點位置外，也會聚焦於側壁，造成無法形成單一聚焦。本研究探討使用不同流道寬度及流體下，側壁效應對粒子聚焦位置的影響。

In this study, we investigated how the sidewall effect influences the location of pressure nodes or pressure anti-nodes in standing surface acoustic wave(SSAW) microfluidics. Both the medium and channel width were varied. It is found that the sidewall effect affects the distribution of nodes and anti-nodes so that they deviate from the positions which are computed by the 1-D model. Meanwhile, the distribution of nodes (or anti-nodes) is not uniform and equidistant.
The particles in DI water tend to be focused on nodes at the boundary of the microchannel instead of focusing on theoretical nodes which are close to the sidewalls. In glycerol-water solution with ratio 7:1, the anti-nodes (particles position) will be affected by the sidewall effect, and pushed to the middle of the flow channel.

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