利用界面活性劑於介電濕潤驅動液滴間形成虛擬微流道

Abstract

近年來，微觀尺度下建立微流道的技術已相當成熟，為了改善微流道由於物理邊界而導致操作上尺寸及設計靈活性的減少，本論文利用介電濕潤（Electrowetting-on-dielectric）作為驅動液體的機制，於數位微流體操控平台上，提出一種無固體邊界且具有重現性的虛擬微流道（Virtual microchannel）。在去離子水中加入臨界微胞濃度（Critical micelle concentration, CMC）之Pluronic F127、Pluronic F68、TWEEN 20以及Triton X-100等界面活性劑，液體及虛擬微流道皆在兩平行ITO玻璃基材結構間移動和形成，利用界面活性劑會降低液體表面張力的特性，在兩顆液滴之間可輕易地形成一可任意改變型態和寬度的虛擬微流道。藉由不同設計之電極，可建立不同型態、長度（1000 um至5000 um）、高度（20 um至180 um）的虛擬微流道陣列，並利用共軛焦顯微鏡觀察，在高度為100 um下，該虛擬微流道可達1.74 um的寬度，使其深寬比達60。再者，於虛擬微流道的兩端施予不同電壓值，使液體由於兩端的壓力差形成一幫浦，並加入1 um的粒子，其憑藉著液體的流動，於流道口一次一顆噴濺而出，目前得到液體流經虛擬微流道的流量約為0.0088 nL/s至0.0382 nL/s，進一步將該技術用於DNA拉伸。本論文提出一種簡單的無固體邊界之虛擬微流道建立方法，不僅具有可重複性，且可整合其他微流體應用於單一晶片，並利用液體幫浦移動溶液中的粒子或DNA。

In recent years, constructing flow channels on a micro scale has been intensively investigated. In order to improve the flexibility of the microchannels by removing their physical sidewalls, we demonstrate reprogrammable virtual microchannels on a digital microfluidic platform using electrowetting-on-dielectric (EWOD). We added different kinds of surfactants, Pluronic F127, Pluronic F68, TWEEN 20, and Triton X-100 to distilled deionized (DD) water at their critical micelle concentration (CMC). The virtual microchannels were established between two parallel Indium Tin Oxide (ITO) coated glass plates. A reprogrammable virtual microchannel without physical sidewalls between two droplets was achieved and stabilized simply due to the surfactant molecules. By using different patterns of the electrodes, we created virtual microchannels in various forms, lengths (from 1000 um to 5000 um), and heights (from 20 um to 180 um). We obtained high aspect ratios as 60 when the virtual microchannel was 100 um high and 1.74 um wide. We applied different voltages on the two sides of the microchannel to generate uneven pressure and to pump the liquid. Furthermore, we put 1 um particles into the liquid for visualizing the flow. Individual particles passing through the microchannel at a time were observed. The pumping rate was about 0.0088 nL/s to 0.0382 nL/s. Moreover, DNA molecules were stretched with the flow in the virtual microchannels.