應用於細胞分離之線形捕捉全像雷射鑷夾的設計與分析

Abstract

在當前生醫科技的發展熱潮中，快速診斷的能力與效率是提升醫療服務的先決條件。因此，建立更快速分離檢體細胞或病菌的新技術，是生醫科技中熱門的關鍵技術之一。現行最常用的細胞分離儀器為流式細胞儀及微流體實驗室晶片。然而，前者體積龐大又價格昂貴，而後者微結構複雜且管道容易阻塞。近年來，全像雷射鑷夾以其非接觸式捕捉搬運多細胞的優勢，若能再結合微流管道導引細胞的功能，可加速細胞分離的效率。因此，本論文提出結合全像雷射鑷夾系統與微流管道，發展一種線形捕捉雷射鑷夾在微流管道中能快速分離微粒子的新技術。 在本研究中，我們建構一套線形捕捉全像雷射鑷夾系統，並建立模型分析線型雷射鑷夾捕捉微粒子的捕捉力。在系統上，我們利用一台可程式化相位調變器（PPM），經由電腦輸入相位圖樣後，會在像平面產生一線形光圖案，此線形圖案即為線形捕捉微粒子的圖案。配合微流管道，此整合系統即具有操控及分離微粒子的功能。接著在理論模型上，藉由線形圖案作用在不同微粒子的捕捉力以及水流推動微粒子的水流黏滯力，決定細胞之間的分離距離。並且從分離距離得到最佳的分離效果，以達到快速分離微粒子的目標。 在研究結果中，我們模擬並實際量測出線形雷射鑷夾捕捉力。從理論值與實驗值中，我們共比較133處位置的捕捉力，其平均誤差百分比為5.5%，由此數據證明模型具有準確性。接著，我們以模型模擬半徑1.5與3 um微粒子在改變水流速與線形圖案角度條件下的分離距離。在線形長度為22.5 um之下，我們找出最大分離距離為14.5 um，並對應最佳分離條件為水流速是217.5 um/s；線形角度為77。根據模型的分析結果，我們就可以應用在系統上，得到最佳的分離效果。此一結合全像雷射鑷夾與微流管道以動態及可連續操作方式進行細胞與分子生物的捕捉、導引與分離，是一個創新的研究。

Rapid and sensitive diagnoses are the prerequisition in developing advanced biomedical technology. Cell and bacteria separations are the basis of the diagnostic technology. Currently, flow cytometry and microfluidics lab-on-a-chip are the two techniques most commonly used for these purposes. However, the former is often bulky and expensive and the latter is complex microstructures and are difficult to manufacture. In recent years, the Holographic optical tweezers (HOT) becomes famous for its non-contact in trapping and manipulating cells. If it would be combine with the guiding function of microchannels in the efficiency of cell separation would enhance. Therefore, we propose the HOT system along with microchannels to develop a novel technique of holographic-optical-tweezers-based line traps in rapid cell separation. We constructed a holographic-optical-tweezers-based line traps system and established a theoretical model for the line trap. We utilize a programmable phase modulator (PPM) to generate an optical line pattern by controlled phase pattern. The beads were trapped by the optical line pattern. Based on the HOT and the designed microchannel chip, the integrated system became a powerful tool for manipulation and separation of cell. In the model, base on the trapping force exerted by the line trap and the water-dragging-force exerted by the flowing water on the bead, the separation of beads is determined. Then, we can base on the separation to obtain optimal separation condition and to complete the goal of rapid cell separation. The optimal operating conditions of a lab-on-a-chip type holographic-optical-tweezers based line trap for cell separation were analyzed. The trapping forces exerted on the respective beads were measured experimentally at 133 separated positions around the line pattern. The agreement between the experimental data and the calculated values is better than 5.5%. Moreover, we simulate the trajectory of individual bead flowing through the line pattern in the microchannel. In particular, we found the optimal operating conditions, in terms of the water flow velocity is 217.5 um/s and its angle with the line pattern is 77, for obtaining the maximum bead separations is 14.5 um with the line trap. Base on the result, we can apply it in the system for the optimal cell separation. A holographic-optical-tweezers based line trap combined with a microchannel chip could be a dynamic and continuous operation in trapping, guiding, and separating cells.