施加多重驅動訊號於環形電極陣列所產生的電動力學效應之研究

Abstract

本研究成功開發出一款新型的奈米粒子聚集裝置，其包括環形電極陣列(Circular Electrode Arrays)、微流體晶片(Microfluidic Chip)及電路系統(Electrical System)三大部分。透過輸入單一低頻且不同實驗條件的交流電訊號於環形電極陣列中，可以比較其電動力學效應的差異，而隨著環境溶液的離子濃度提高時，電雙層屏蔽效應會導致其操控粒子的能力下降，最後再透過施加多重訊號於環形電極陣列中，突破電雙層屏蔽效應，使環形電極陣列在離子濃度提高的情況下，仍能收集一定數量的奈米粒子於其表面上。 本研究分為三大部分：環形電極陣列部分，透過電極寬度和電極間距等比例沿徑向方向增加的設計，使得施加具有相位差的交流電訊號於環形電極陣列後，能產生耦合旅波電滲透和介電泳的電動力學效應，而使裝置無需連接外部的幫浦，並能收集奈米級粒子於電極陣列表面的中心線上；電路系統部分，透過整合外部的類比開關於電路中，可以產生低頻方波中載以高頻波，且能同時開、關的交流電訊號，不僅能產生更強的電動力學效應去突破電雙層屏蔽效應，也使實驗設定的操作空間變得更加靈活；螢光強度分析部分，不僅可以透過螢光粒子的運動行為了解電動力學效應，更進一步透過影像處理軟體去分析電極陣列上的螢光強度變化，量化聚集奈米粒子的效果及電雙層屏蔽效應的影響。 操作實驗時，在環形電極陣列中的每根電極以相位差相差90度的模式施加交流電訊號，透過不均勻的電場產生介電泳現象，而電滲透則是透過電場的切向力使擴散層中的電解質移動，再由移動的電解質牽引環境溶液流動，然後耦合的電動力學效應會將微流道腔體中的奈米螢光粒子收集至電極陣列的表面上，而奈米螢光粒子運動的過程會由光學系統完成拍攝，最後再以影像處理軟體分析螢光強度的變化。 此研究成功提出一種低成本、製程時間下降且無需外部幫浦的樣品準備方法。此外，透過施加多重驅動訊號所產生的電動力學效應，可以有效突破電雙層屏蔽的影響，而強化收集奈米粒子的功能。

In this research, we successfully develop an innovative nano-particle accumulation device, including three components such as Circular Electrode Arrays, Microfluidic Chip and Electrical System. We compare different electrokinetic effects by applying different-amplitude, low-frequency and single-waveform AC signals into Circular Electrode Arrays. Besides, the Debye-shielding effect will cause negative impact on particle manipulation when the ion concentration of medium increases. To break through the shielding effect, we apply multiple-driving waveform AC signals in Circular Electrode Arrays, induce stronger electrokinetic effects and then finally collect a certain number of nano-particles on the surface of electrodes. This research is divided into three parts: (1) Circular Electrode Arrays, they are displayed in radial form, contain 16 electrodes in total and the line width and gap between electrodes increase along radiant direction. With this design, we generate coupling electrokinetic effects of Traveling Wave Electroosmosis (TWEO), Dielectrophoresis (DEP) to concentrate nano-particles onto center line of electrode surface after applying AC signals which contain 90-degree phase difference. (2) Electrical System, we integrate analog switches into circuit board. By doing so, we don’t only break through shielding effect with multiple-driving waveform AC signals, but enable experimental operation to have a wide range of settings. (3) Analysis of fluorescent intensity, we understand coupling electrokinetic effects substantially by observing fluorescent particle motion. Besides, we quantify the performance of particle accumulation and the influence of Debye-shielding effect by analyzing the variation of fluorescent intensity on Circular Electrode Arrays. During the experiment, we divide Circular Electrode Arrays into 4 sets and each set is applied with voltage, V_0 cos⁡(ωt+φ_i), where the phase terms φ_i are 0˚, 90˚, 180˚ and 270˚ in sequence. In this circumstance, DEP is induced by nonuniform electric field. As for electroosmosis, it is the phenomenom that the electric tangential force moves the electrolytes in diffusion layer, and the moving electrolytes drive the medium. After the coupling electrokinetic effects are generated, the fluorescent nanoparticles will be collected onto the surface of Circular Electrode Arrays. In the same time, the particle motion is recorded by optical system. Finally we will use image processing software to analyze the variation of fluorescent intensity. An efficient solution for sample preparation is offered in this research. Remarkably, this solution is low-cost, time-saving and without interconnection of external pump. Furthermore, we effectively break through the Debye-shielding effect by applying multiple-driving waveform signals into Circular Electrode Arrays, and finally enhance the performance of collecting nano-particles.