光誘發交流電動力操控微米磁珠之最佳化研究

Optimization of Manipulating Magnetic Microparticles Using Optically-induced AC Electrokinetic Force

洪嘉隆(Jia-Long Hong)

指導教授 ： Ping-Hei Chen 陳炳煇

共同指導教授 ： Min-Hsien Wu 吳旻憲

國立臺灣大學/工學院/機械工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201704339

摘要

在生命科學研究領域，微米磁珠操控已被廣泛應用於細胞或生物分子的純化分離及生物感測。近年來，隨著微流體技術的發展，在微流體系統中結合微米磁珠的操控已被成功展示於各種生物相關研究。然而，這些微米磁珠操控大多依賴實體磁場的施加與控制，這方法除了需要耗時及耗成本的加工製程外，其微米磁珠之操控性亦缺乏彈性。有別於此，在微流體系統內利用光誘發交流電動力來進行微米粒子操控，則提供一項低成本且彈性度高的微小粒子操控平台，其原理係透過光源所投射出的光圖形至光電半導體層(氫化非晶矽)上，進而誘發光電效應來操縱微小粒子(例如: 細胞或乳膠顆粒等)。然而，利用這項原理來操控微米磁珠的研究相對比較缺乏，因此本研究擬探討在微流體系統內，利用光誘發電動力來操控微米磁珠之理想操作條件。在本研究中，我們在不同操作條件 (包含:氫化非晶矽厚度、操作頻率、粒子大小及液體導電度)下，分別探討磁珠能夠被光圖形拉動的最大速度，來做為評估操控性的依據。實驗結果顯示，在施以低頻率(＜50kHz)的交流電壓時，在光驅動交流電滲流的作用機制下，不同大小微米磁珠的最大可操控速度均有所提升；當氫化非晶矽層的厚度由1000 nm降至500 nm時，1 µm直徑磁珠的最大可操控速度提升了約53%至1441 (µm/s)。相反地，當施以高頻率(>50kHz)的交流電壓下，微米磁珠操作機制主要為光介電泳現象；當氫化非晶矽層的厚度為1000 nm時有最佳表現；其中，此條件下粒子越大其終端速度越高，且在高導電度背景液中趨勢一致。整體而言，再施以低頻率的交流電壓時，利於對微米磁珠做高速操控；在高頻時，雖然最大可操控速度較低，但有利於分離不同大小的微米磁珠。上述的研究提供我們一項在微流體系統內以更方便、及更具彈性的方式來操控微米磁珠的操作條件，這將有利於各種在微流體系統內利用微米磁珠的應用研究工作。

關鍵字

微米磁珠 ； 光誘發交流電動力 ； 光介電泳 ； 光驅動交流電滲流 ； 氫化非晶矽 ； 微流體系統

並列摘要

In the field of life science, manipulation of magnetic microparticles (MMPs) has been widely used in the isolation and purification of cells or biomolecules, and bio-sensing. With the recent progress in microfluidic technology, the integration of MMPs manipulation in a microfluidic system has been successfully demonstrated for a wide variety of biological-related applications, showing superior performances over their macro-scale counterparts. However, the manipulation of MMPs in these microfluidic systems mainly relies on the exertion and control of physical magnetic fields, which normally requires technically-demanding, and high-cost microfabrication process to create metal electrodes. In addition, these manipulating methods are, to some extent, not flexible, and user-friendly. Conversely, the use of optically-induced electrokinetic force in microfluidic systems could provide a low-cost and highly-flexible platform for microbead manipulation. The working mechanism is based on the control of light patterns projected onto a photosensitive material (e.g. hydrogenated amorphous silicon, a-Si:H) to induce the photoelectric effect for manipulating microparticles (e.g. cells or latex particles). However, the use of this technique for MMP manipulation has not been well studied. To address this issue, this study aimed to investigate the optimal operating conditions for the manipulation of MMPs in a microfluidic system. In this study, we evaluated the maximum velocities of a light pattern that can manipulate MMPs under different operating conditions including a-Si:H thickness, the frequency of electric field, size of MMPs, and liquid conductivity. Results showed that the manipulation velocity of MMPs with different sizes were all significantly increased when the electric frequency was decreased. In addition, when the thickness of a-Si:H was reduced from 1000 nm to 500 nm, the maximum manipulation velocity of MMPs (D: 1 μm) increased to 1441 (μm/s) (53% increase). Conversely, when the frequency of electric field was greater than 50kHz, the working mechanism for MMP manipulation was mainly dominated by optically-induced dielectrophoresis. Within the experimental conditions explored, the a-Si:H with 1000 nm thickness was found to have a better performance of particle manipulation. Moreover, it was also found that the MMPs with larger size showed to have higher manipulation velocity than that with smaller size. The presented research has provided the information for the optimal manipulation of MMPs using optically-induced AC electricokinetic force in a microfluidic system. Based on this study, overall, it can be suggested that the higher (e.g. >50kHz), and lower (e.g. <50kHz) electric frequency were found useful for the applications in which size-based MMP sorting, and high-speed MMP manipulation were required, respectively.

並列關鍵字

magnetic microparticles (MMPs) ； optically-induced dielectrophoresis (ODEP) ； light-actuated AC electroosmosis (LACE) ； hydrogenated amorphous silicon (a-Si:H) ； microfluidic system

參考文獻

[1] McDonald, J. C., Duffy, D. C., Anderson, J. R., Chiu, D. T., Wu, H., Schueller, O. J. A., and Whitesides, G. M., 2000, “Fabrication of Microfluidic Systems in Poly(Dimethylsiloxane),” Electrophoresis, 21(1), pp. 27–40.

[2] Grayson, A. C. R., Shawgo, R. S., Johnson, A. M., Flynn, N. T., LI, Y., Cima, M. J., and Langer, R., 2004, “A BioMEMS Review: MEMS Technology for Physiologically Integrated Devices,” Proc. IEEE, 92(1), pp. 6–21.

[3] Manz, A., Graber, N., and Widmer, H. M., 1990, “Miniaturized Total Chemical Analysis Systems: A Novel Concept for Chemical Sensing,” Sens. Actuators B Chem., 1(1), pp. 244–248.

[4] Reyes, D. R., Iossifidis, D., Auroux, P.-A., and Manz, A., 2002, “Micro Total Analysis Systems. 1. Introduction, Theory, and Technology,” Anal. Chem., 74(12), pp. 2623–2636.

[5] Vargas, E., Povedano, E., Montiel, V. R.-V., Torrente-Rodríguez, R. M., Zouari, M., Montoya, J. J., Raouafi, N., Campuzano, S., and Pingarrón, J. M., 2018, “Single-Step Incubation Determination of MiRNAs in Cancer Cells Using an Amperometric Biosensor Based on Competitive Hybridization onto Magnetic Beads,” Sensors, 18(3), p. 863.