光電鉗系統之微小物體運動控制的觀察與探討

Abstract

近幾年發展了許多有關於微小物體的操控以及分離不同生物細胞的生醫檢測技術，譬如：磁鉗、光鉗、介電泳動、光電鉗等，其中光電鉗因為同時擁有光鉗的即時操控性以及介電泳動的大範圍同時多點獨立操控的優點，且所需花費的時間也相對減少了許多，因此成為一項值得開發的重要技術。光電鉗利用透鏡組將投影機的影像聚焦在樣品盒內的光導電層基板上，使其光控制投影區域的阻抗值小於樣品盒內環境的阻抗值，接著施加一交流電壓時，讓樣品盒內形成一不均勻電場產生介電泳力，而樣品盒內的介電物質即會受此力影響而開始進行移動，我們利用此一原理來達到操控樣品盒內的微小介電物質。 本論文以光電鉗研究直徑為20 μm的塑膠小球在水溶液中的運動特性。根據本論文的研究結果，可調整樣品盒內的介電環境與適當的交流電操縱頻率產生擁有足夠的介電泳力操控微小介電物質。在二維平面系統的光電鉗實驗當中，當樣品盒內的介電物質以及介電環境的介電常數和導電率為已知時，可預先計算其介電泳力的大小以及方向。在三維空間系統的光電鉗實驗當中，我們發現了介電物質在樣品盒中具有Z軸方向的運動空間，此研究將光電鉗技術從二維平面的操縱維度擴展到三維空間，且可以簡單地操作介電物質與光控制投影區域之間的距離，控制介電物質在樣品盒中的高度變化。

Many techniques have been developed to manipulate micrometer-scale particles and biological cells in recent years, such as magnetic tweezers, optical tweezers, dielectrophoresis (DEP) and optoelectronic tweezers (OET). Among them, the OET system has emerged as a powerful technique for dynamic and massively parallel manipulation of particles. The operational principle of the OET device is to produce an optically controlled DEP force generated by the high-resolution patterning of electric fields on a photoconductive surface for manipulating single particles. In this work, we demonstrated the manipulation of 20 μm polystyrene beads in the de-ionized water solution by using OET. The optically controlled DEP force was adjusted by changing the driving frequency and the permittivity and the conductivity of the de-ionized water. The DEP force can be calculated in advance as long as the permittivity and the conductivity of the polystyrene beads and the de-ionized water are known. We also found that the polystyrene beads travel in the Z-axis direction of the cell from the observation of their motion. The manipulation of particles in three dimensional spaces can improve the performances and widen the applications of the OET.