表面聲波(surface acoustic wave)可對於微流體裝置中的粒子進行聚集或分離，其作法乃是在壓電材料上利用黃光微影製程技術(photolithography)製作出微流道裝置，並在微流道兩側加上指叉狀電極(inter-digital transducer)，由於逆壓電效應(converse piezoelectric effect)，指叉狀電極輸出的電能轉換成機械能，在表面產生表面聲波並使微流道內流體產生壓力差，造成流體中粒子的聚集或分離。影響表面聲波聚焦的因素，除了一般文獻中常提到的粒子大小、輸出功率之外，本研究針對其他變數如工作頻率、壓縮性(compressibility)作進一步的探討。
微藻是現今開發生質能源的重要原料之一，有生長速率快與高含油量的特性，因此發展快速檢測並篩選高含油量藻種的技術將有助於生質能源的開發。本研究亦嘗試利用表面駐波(standing surface acoustic wave, SSAW)的方式對於Nile red染色後的小球藻(chlorella vulgaris)聚焦，探討對於單顆微藻進行連續式、快速、無侵入性的油含量檢測的可行性。

Surface acoustic wave (SAW) is one of the techniques which can be applied to focus or separate microparticles in a microfluidic device. Through photolithography, the inter-digital transducer (IDT) is fabricated and integrated with microchannel. The alternating current electric field with appropriate frequency is applied and electric energy is transferred into mechanical energy owing to the converse piezoelectric effect. Pressure gradient is generated in the microchannel and the particles are focused or separated. The variables which will affect SAW such as particle size and output power are widely discussed and found in the literatures. In this study, the effect of the working frequency and compressibility of the medium is explored.
Microalgae are an important source for biomass energy. Due to their high growth rate and high lipid abundance, developing a strategy for high throughput detection of lipid inside microalgae is critical. In this study, we attempt to apply SSAW to focus the algal cells and study for feasibility of performing continuous detection of lipid content inside microalgae.

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