表面聲波微流體晶片是以聲輻射力作為驅動力來操控粒子。與傳統聚焦技術不同的是，該方法不需對粒子進行前處理，便可使流道內粒子根據本身性質而聚集排列。此外，還具備高生物相容性及低能耗的優點，因此適用於任何微粒或細胞。然而，在聚二甲基矽氧烷(PDMS)與表面聲波駐波(SSAW)組成的表面聲波微流體晶片中，具正聲波對比因子的聚苯乙烯(PS)粒子不僅會在流道內的壓力節點上對準排列外，亦會在流道側壁發生側壁效應(sidewall effect)而產生聚焦，使得粒子無法有效形成單一聚焦。
本研究旨在探討改變表面聲波微流體晶片中指叉狀電極(IDT)的設計參數(如電極傾斜角度和單根電極寬度等)及微流道的幾何結構對側壁效應的影響，同時比較不同晶片貼合方式(聯結層貼合/直接貼合)下的效果差異，藉此達到消除側壁效應的目的。研究結果顯示，V形排列電極(V-shape arranged IDTs)設計及方彎流道(square-bended microchannels)結構皆有助於使原本受側壁效應影響的粒子遠離流道側壁，其中又以添加突出物之雙方彎流道直接貼合晶片時的效果最佳。

In the PDMS, SSAW-based microfluidic chips, the particles with positive contrast factor are not only focused on the pressure node but also aggregated on the sidewall. This phenomenon is referred to as the sidewall effect and, as a result, particle manipulation such as sorting, counting becomes less effective. In this study, eliminating the sidewall effect by utilizing different designs of IDTs and microchannels was proposed. The processing parameters such as the tilted angle, the stripline width of V-shape arranged IDTs, single square-bended and double square-bended channels, microchannels with protrusion, with and without coupling layer were investigated.
The results showed that the designs of V-shape arranged IDTs and square-bended microchannels were both beneficial to eliminate the sidewall effect. The optimal condition was to use the directly bonded chips and double square-bended channels with protrusions.

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