摘要
介電泳(Dielectrophoresis)已在生醫領域被廣泛地利用，能夠透過其對於奈米尺寸粒子進行操控，例如:蛋白質(protein)、去氧核醣核酸(deoxyribonucleic acid ，DNA)、及病毒等。然而目前已知慣用介電泳力公式(conventional dielectrophoretic)在實際操作上低估了奈米粒子所受介電泳力大小約三個量階，因此研究者近年提出了微觀介電泳公式(microscopic dielectrophoretic)，而微觀介電泳包含部分之經驗公式且尚未經過完整之驗證，本文主要之目標為透過挑選具有代表性之實驗對微觀介電泳進行驗證。 本研究利用有限元素分析軟體(COMSOL)對微觀介電泳進行驗證，藉由計算粒子在受到不同介電泳力、流體阻力、及布朗運動作用力情況下分析其運動軌跡，或是將蛋白質視為一稀薄懸浮液的濃度，利用質傳公式計算其濃度分布。透過選定之五個實驗進行比較，分別研究以電極通電所驅動的介電泳 (electrode-based DEP)或以絕緣體置於電極間所引致之局部增強介電泳 (insulator-based DEP)、輸入直流電或交流電、及是否有奈米絕緣柱等條件，微觀介電泳和其中四個實驗在定性和部分定量上和結果相符，然而慣用介電泳則是連布朗運動之擾動都無法克服，其中結果不相符的一實驗是因為粒子運動受到強勁的電滲作用(electroosmosis)所主導，因此目前透過經驗公式，微觀介電泳能在實務上有效地進行預測。 由於蛋白質本身具有永久偶極矩以及帶有淨電荷，在施加外加電場下，會受到偶極矩力(dipole force)和庫倫作用力(Coulomb force)作用，本研究也對此兩種可能之作用力來源進行探討。初步研究結果顯示偶極矩力能夠克服布朗運動，其大小約介於微觀介電泳和慣用介電泳之間，且在數十顆粒子鍊結效應(chain effect)下其作用力大小和微觀介電泳相當。另外再不考量電荷之屏蔽效應(screening effect)下，庫倫作用力遠大於微觀介電泳。偶極矩力和庫倫作用力的研究都能對日後蛋白質介電泳理論的發展有所助益，並且值得進一步研究。
並列摘要
Dielectrophoresis (DEP) is applied extensively in biomedical application and is capable for handling nano-sized particles, such as protein, deoxyribonucleic acid (DNA) and virsus. However, it is also well known that the conventional dielectrophoretic force equation (called FcDEP here) underestimate the dielectrophoretic force in practice by three orders of magnitude, and thus a so-called microscopic dielectrophoretic force equation (called FmDEP here) was proposed recently. FmDEP is somewhat empirical and was not fully validated. Thus, the primary goal of the present work is to provide validation of FmDEP, via typical experiments. The validation was performed numerically via the aid of COMSOL software, by solving either the particle motion subject to various form of dielectrophoretic force, viscous drag and Brownian force, or the mass transfer equation, treating the movement of protein particles as concentration evolution. Through the comparison of five selected experiments, including electrode-based and insulated-based DEP, DC and AC signals, nanoelectrodes and nanorods, FmDEP predicted four experiments qualitatively and even quantiatively, while FcDEP could not even overcome the random Brownian movement of particles. The experiment which could not be predicted by FmDEP probably because it is overwhelmed by the large electroosmosis effect. Thus, the current microscopic model, FmDEP, though empirical, could be applied in practice. As the protein contains inherently permanent dipole moment and net charges, it experiences dipole force (FpdDEP) and Coulomb force (FCoulomb) when it is subject to an applied electric field. Both FpdDEP and FCoulomb forces were also studied here as potential forces for the movement of protein particles. Preliminary study indicates that FpdDEP could overcome the Brownian effect and lies between FcDEP and FmDEP, it could provide a comparable effect as FmDEP if tens of protien particles coagulate as one. On the other hand, FCoulomb is too large in comparing with FmDEP in the absence of screening effect of charges. Both FpdDEP and FCoulomb could be helpful for further development of the theory of protein dielectrophoresis, and deserve further study.