反射式顯示介質：分散於固化相之乳化液滴內粒子驅動

Abstract

本實驗整合微流體、粒子極化與介電泳等技術，透過在微流道中建立具乳化液滴結構的顯示元件，達到反射式顯示介質之功能。反射式顯示器具有不需要背光模組的優勢，不僅可節能省電，更可避免使用者們長時間觀看下的不適感。以往這些顯示器在像素結構的建立、液體封裝及填充，都是透過微機電製程的技術來完成。本實驗透過微流道乳化技術，將這些相關的製程簡化並實現在一片微流體晶片上。實驗內容以建立單層的乳化液滴陣列為核心，液滴組成為水溶液包覆均勻分散二氧化鈦粒子(Titanium dioxide)或聚苯乙烯球(Polystyrene，PS)，而環境的液體為熱固化的聚二甲基矽氧烷(Polydimethylsiloxane，PDMS)及光固化的油MD700、NOA 74，當液滴緊密的在微流道中堆疊出陣列結構，再透過環境液體的固化，可以得到整個顯示介質的封裝。實驗中可透過開板的方式取出封裝好的薄膜顯示介質，在置於平行板晶片中操控，或者直接於流道中整合電極晶片進行操控，施以電壓40 V及頻率1 MHz之交流電訊號控制微奈米粒子。首先粒子受電場影響極化成串，接著受介電泳力而聚集於球體邊緣，達到介電泳顯示器的作用，並在移除電壓後分散回來，達到3秒的反應時間，以及對比度5:1的顯示效果，驗證了以微流體液滴系統實現介電泳顯示器之功能。

We developed a particle-based reflective display medium fabricated with microfluidic emulsion technique and driven with dielectrophoresis (DEP) and particle polarization. Without backlight, the reflective displays are power saving and offer comfortable viewing experience for a long time. However, the fabrication of particle- or liquid-based reflective displays require several critical and complicated processes including liquid filling and packaging without leakage. In this thesis, the fabrication processes were simplified and implemented on a microfluidic chip through the microfluidic emulsion technique. The emulsion droplet array in this study consisted of dispersed droplets with suspended titanium dioxide or polystyrene particles. The droplets were surrounded in a continuous phase of thermally crosslinkable polydimethylsiloxane (PDMS) or photo crosslinkable MD700 or NOA74. The encapsulation of the display medium was obtained after crosslinking the continuous phase after the formation of the droplet emulsion array. We then opened the microfluidic device to retrieve the crosslinked thin film display medium. The display medium was consequently placed between parallel plates containing electrodes for driving with an appropriation electric signal. The particles were polarized to form particle chains and moved by DEP to the sides of the droplets where the electric field was weak. With the 40 V and 1 MHz AC electric signal, the response time was 3 s to achieve a contrast of 5:1.