近年來隨著生醫產業的蓬勃發展,無論是在生物檢測、病原體分析、藥物篩檢、化學合成、食品安檢、環境評鑑，微米粒子的分離或排序都佔有重要的一席之地。簡便的分離方式較能順利進行分析和鑑定，而傳統方法的缺點為，儀器設備昂貴、分析時間冗長、分離步驟繁雜等都會增加上述流程的難度。雖然現今已開發出許多分離與聚焦粒子的技術，但相較於其他方式，聲輻射力根據粒子或細胞的大小、密度、壓縮比來進行區分的特性，造成其不需要對細胞預先標記或是表面改質，可以使細胞在新鮮的狀態下進行分離，且適合幾乎所有種類的微粒。同時，利用SSAW裝置來控制粒子或細胞移動到壓力節點或反壓節點，分離和聚焦的過程具有很高的操作性、靈活性和生物相容性。
本研究旨在探討高電壓聚焦所可能產生的邊壁聚焦效應，及相應的解決辦法，當Polystyrene粒子，小球藻(chlorella vulgaris)或是大腸桿菌(E.coli)進行聚焦時，如何完善的將Polystyrene粒子或微藻進行連續式排列至正確的位置。由實驗結果可知，當我們藉由調配溶劑的物理組成，可以處理幾乎所有流道尺寸、粒子濃度、流體流速的邊壁效應問題。

In this study, both preventing aggregation of microparticles near the channel side walls and separation of microparticles by SSAW were investigated. Aggregation of microparticles near the side walls (ie, side wall effect) occurs when using the PDMS based microchannels where the pressure nodes are near the side walls. It was shown that , by using 5:1 glycerol solution as the medium, the acoustic contrast factor became negative, the acoustic microparticles were focused at the pressure anti-nodes, which were away from the channel walls. As to the particle separation, a serpentine channel was placed asymmetrically between the IDTs, such that microparticles with different sizes experienced different acoustic radiant force. The result showed that 5 and 10 um particles can be separated with high separation efficiency.

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