電動微流晶片之粒子操控與分析

Abstract

生物微流體晶片於醫學檢驗的應用，在這幾年越來越被重視，傳統的檢測方法，有檢測儀器過大、耗時耗力、繁瑣的步驟等缺點，隨著微小化技術的進步與其應用的普及，可以改善上述問題。整合多種生物、化學分析等功能於單一微小型晶片(lab-on-a-chip)因此被開發，是各團隊致力研究的目標。此外在某些應用上，快速收集與準確定位的粒子操控技術通常是生物檢測晶片的核心技術。 本論文藉由非線性電動力學(electrokinetic)中的誘導電滲(induced-charge electro-osmosis)與絕緣介電泳(insulator-based dielectrophoresis)，開發一個操縱聚苯乙烯微球的微流晶片，應用於收集(放大標的粒子的螢光訊號和後端定量分析)與釋放(回收與再分析)低濃度懸浮生物粒子。此晶片使用經過雕刻的絕緣膠帶(厚度約40 μm)當作絕緣體，並置於上下電極中間來產生不均勻的電場。此外透過往復式運動流體來提高顆粒的抓取效率。通過實驗和COMSOL Multiphysics模擬軟體分析絕緣體的幾何形狀、上下電極間距及交流訊號後，結果顯示在低頻率的時候，電滲的力量使懸浮粒子收集在裸露電極中間的表面停滯區域上，而在高頻率的時候，介電泳主導粒子的運動，使聚集在裸露電極正上方的粒子釋放到流速大的上方區域。透過控制絕緣體之幾何參數與交流電訊號，可以影響不同電動力之間的強度，而在特定參數組合下，使晶片達到最佳抓取與釋放效率。

Due to the progress of microfabrication technology, a wide range of bioengineering applications including high throughput drug-screening chips, miniature diagnostic kits, and biochips have been developed. A microfluidic chip, or so-called lab-on-a-chip, has the advantage of reduced labor, time, cost, and reagent consumption. Furthermore, in some applications, particle manipulation to enable accurate localization of target particle is a significant core technology for bio-particle collection and concentration. This thesis presents a microfluidic chip combined with two electrokinetic phenomenon – induced-charge electro-osmosis (IC-EO) and insulator-based positive dielectrophoresis (i-pDEP) – to manipulate polystyrene particles, particularly to collect and release bio-particles with low concentration. Collection of these elements is often to enable subsequent analysis and quantification, where release is for recovery and further analysis. Non-uniform electric field is generated from patterned double-sided adhesive tape (about 40 μm) as insulator between the top-and-bottom electrodes. In addition, features to realize reciprocating flow is designed to increase the collection efficiency of the particles. The geometry of the insulator, distance between top-and-bottom electrodes, and the AC signal were analyzed by the COMSOL Multiphysics software. Results show at low frequency, the suspended polystyrene particles are collected at the stagnation region on the surface of the bottom naked electrode. On the contrary, at the high frequency, the i-pDEP would dominate the movement of particles and further release the particles from accumulation region to upper region where the flow velocity is high. The strength of the electokinetic forces are affected by controlling the geometry parameters of the insulator and the electric signal. Results should contribute to improved understanding of the interaction of electrokinetic forces in a microfluidic chip.