多管微流道同步機制與高通量「太極塗佈」系統之開發研究

Abstract

隨著消費性電子產品的需求逐年提升，各式各樣的塗佈技術已被大量應用於高科技產業，其中不需母模的圖案化塗佈技術因其環保節能的特性，已漸漸成為發展主流。太極塗佈法即是一新興的不需母模圖案化塗佈技術，透過將間斷式的液氣微雙相流連續地塗佈於基材上而產生非連續的塗佈圖案，具有作動簡單、塗料黏度適用範圍廣及可兼容捲對捲(roll-to-roll)方式生產等優越特性。本研究為將此新興技術推廣至工業化量產的前導型研究，根據所需開發的關鍵技術將論文架構分為三大部分： I. 液氣微雙相流即時尺寸控制系統之開發： 此部分首先探討流體輸入源對液氣微雙相流尺寸均勻性的影響，發現一般慣用的針筒式幫浦將對微雙相流尺寸產生約±20%的尺寸變異，而定壓力輸入源則能產生尺寸變異係數小於0.73%的均勻微氣泡與微液滴。接著透過等效單相流模型分析，成功預測出太極塗佈法必要之段塞流模態的操作區間，並找出影響此操作區間大小的關鍵因子：微流管道幾何流阻比G*。最後則開發出一可即時控制液氣微雙相流尺寸變化的閉迴路系統，於微液滴和微氣泡尺寸的即時控制變化範圍可達一個數量級，而整體尺寸操控之誤差小於±3%。 II. 液氣微雙相流即時偵測系統之開發： 本研究共開發出電阻感測器與微光纖感測器兩種液氣微雙相流即時偵測系統。電阻式感測系統透過液體與氣體導電程度的差異來辨別彼此，於液氣微雙相流流速和尺寸的量測誤差分別在±1%和±6%範圍內，但工作流體限定為導體。微光纖偵測系統則透過工作流體的折射率變化之感測獲得氣液介面資訊，僅需極微量(100 nL)的檢體便可同時進行微雙相流折射率、流速與尺寸的即時量測，對折射率、流速和尺寸的量測解析度分別為2 × 10-4、50 μm/s和5 μm，足以應用於太極塗佈法之精密定位。 III. 多管道液氣微雙相流同步產生與塗佈機制開發： 本文共研究開發出三種被動式共流體源同步產生液氣微雙相流的結構。第一種混合T型與梯狀微流道設計，利用流體耦合性於雙管道中反相產生液氣微雙相流，且隨著兩管道中的微氣泡越往下游移動，兩者間的相位差會逐漸縮小至接近同步，但難以拓展至三管道以上的應用。第二種為雙擴展角毛細閥門設計，可於雙管道中產生相位相同的液氣微雙相流，但卻有作動頻率較慢的問題。第三種則為三平行聚焦型微流道結合下游梯狀流道的設計，可於三管道中以高頻率產生同相的液氣微雙相流，且易於平行擴展至多流道。而於多管道液氣微雙相流同步塗佈部分，本研究以哈根-泊肅葉定律為基礎，開發出簡易控制多管道分流均勻性的技術，可使各管道間分流誤差小於±1%。此外，本研究也已成功測試出三平行管道可同步塗佈的操作區間，各管間的相位差控制在±4.6º以內。於十管的同步塗佈測試中，則能成功產生相位差小於±7.5º的液氣微雙相流。

With the growing demand for the rapid changes of consumer electronics, a variety of coating methods have been applied in high-tech industries. Among these coating techniques, pattern coating technology has gradually become the mainstream due to its eco-friendly features. Air-Bubble Coating is a novel mask-less pattern coating method, and it generates discontinuous patterns by continuously coating the segmented gas-liquid micro-two-phase flow onto the substrate. It has superior characteristics such as simple operation, wide viscosity applicable range, and good compatibility to roll-to-roll process. This research aims to grow Air-Bubble Coating into an industrial mass production technique. According to the required key technologies, the structure of this dissertation work is divided into three major parts: I. The development of real-time size control system for gas-liquid micro-two-phase flow: First of all, the effect of fluid driven sources on the size uniformity of gas-liquid micro-two-phase flow has been investigated. The commonly used syringe pump would produce about ±20% bubble/droplet size variation while the constant pressure source could generate uniform size of bubbles/droplets with the coefficient of variation less than 0.73%. Second, the operational range of slug flow, which is essential for Air-Bubble Coating, can be well-predicted based on the equivalent single-phase flow model, and the channel geometric factor G* has been identified as the key parameter that affects the scope of slug flow region. Finally, a closed-loop system for controlling the size of gas-liquid micro-two-phase flow in real-time has been developed. The bubble/droplet size variable range of this system reaches one order of magnitude, and the overall size control error is less than ±3%. II. The development of on-line detection system for gas-liquid micro-two-phase flow: An electrical resistance sensing system and an optical microfiber sensing system have been developed to on-line detect the gas-liquid micro-two-phase flow. For electrical resistance detection system, the conductivity difference of liquid and gas was applied to identify the gas-liquid interface, and the velocity and size measurement errors were within ±1% and ±6%, respectively. However, in order to operate properly, the continuous phase fluid must be conductive. In contrast, the microfiber detection system obtains the information of gas-liquid interface based on the refractive index change of the working fluid. With only tiny sample volume (100 nL), the on-line detection of refractive index, velocity, and size can be performed simultaneously. The measurement resolution for refractive index, velocity, and size are 2 × 10-4, 50 μm/s and 5 μm, respectively. This optical sensing system is robust enough for the precision positioning of Air-Bubble Coating. III. The development of synchronization for the generation and coating of multi-channel gas-liquid micro-two-phase flow: Three microfluidic structures for passively maintaining the synchronicity of gas-liquid micro-two-phase flow generation with common fluid sources have been developed. The first microfluidic structure combines the design of T-junction and ladder channels, and it utilizes fluid coupling to generate out-of-phase gas-liquid micro-two-phase flow in two parallel channels. The phase lag between these two channels gradually approaches zero as the bubbles/droplets flow downstream. However, it is difficult to apply this design to more than two parallel channels. The second microfluidic structure is two capillary valves with dual diffusor. It can produce in-phase gas-liquid micro-two-phase flow in two parallel channels, but the working frequency is much lower than the first design. The third one is a three parallel flow-focusing device with downstream ladder channels. It can generate in-phase gas-liquid micro-two-phase flow between all channels with high frequency, and it is suitable to scale up to multi-channel applications. For the multi-channel coating of gas-liquid micro-two-phase flow, a simple technique has been developed to control the uniformity of flow distribution within parallel channels based on Hagen-Poiseuille's law, and the diversion error is less than ±1%. Furthermore, the operational range for three channel synchronization coating has been investigated. The phase difference between each channel can be controlled within ±4.6º. As for ten parallel channels coating, the phase difference of gas-liquid micro-two-phase flow among all channels was less than ±7.5º.