介電濕潤與粒子顯示介質之微流體乳化封裝

Microfluidic Emulsion Packaging of Electrowetting and Particle Display Media

方劭元(Shaw-Yuan Fang)

指導教授 ： 范士岡

國立臺灣大學/工學院/機械工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201802454

摘要

本實驗結合微流道與介電濕潤兩種微流體技術，達到雙層乳化液滴的生成，並測試其介電濕潤顯示的效果，驗證其可作為電濕潤顯示器的可能性。傳統的電濕潤顯示器以黃光顯影製程建立像素邊界結構，之後再加入液體的封填，製程較複雜且時間成本高。為了簡化封裝製程，本實驗透過整合電極式微流道與可固化外相的特色，實現將像素結構的建立、液體封裝與介電濕潤測試結合在一片微流體晶片上完成。實驗中使用可固化外相之熱固化的PDMS或光固化的MD700，搭配中間相的Novec 7500或石蠟油，與內相的水，將一組材料通入雙流道聚焦接口設計的微流道中，測試雙層乳化液滴的生成，發現微流道在經過疏水疏油塗層處理後，以光固化MD700外相/石蠟油中間相/水內相可以形成形狀完整的雙層乳化液滴。在雙層乳化液滴的堆疊穩定度部分，測試了界面活性劑Pico-Surf™與Krytox 157 FSH，以及pickering emulsion粒子氟化二氧化矽加入MD700後的效果。接著以形成雙層乳化液滴陣列為目標，分別測試漸擴型與蜿蜒型下游之微流道的陣列生成效果，並結合共平面電極以驅動介電濕潤，達到完整雙層乳化液滴陣列的顯示效果。於介電濕潤測量方面，在共平面電極板上對固化後之雙層乳化液滴系統施加1 kHz的240 V交流電訊號，使內相水發生介電濕潤效果，正規化可視面積百分比由亮態的47%轉變為暗態的81%，在反應時間的部分，以240 ms達到完全攤平，移除電壓後以300 ms回復至初始狀態，驗證其作為電濕潤顯示器的對比度效果和毫米尺度驅動速度。
我們也提出新的粒子串顯示器結構，以PDMS外相/MD700中間相/含聚苯乙烯粒子的水內相，加上雙層結構微流道成功製造出薄球殼雙層乳化液滴結構，在結合平行板電極後，球殼所包覆之內相的粒子依然能排列成串以產生顯示效果，期望將球殼完整單一固化，形成單分散之乳化液滴像素，解決原先之乳化液滴合併問題。

關鍵字

微流體 ； 反射式顯示器 ； 微流道 ； 介電濕潤 ； 粒子極化

並列摘要

We combined the formation of double emulsions in microchannel and tested the performance of electrowetting-on-dielectric (EWOD) to demonstrate an electrowetting display (EWD). EWD pixels are usually constructed by photolithography and liquid dispensing steps, which are complex and time consuming. To simplify the package processes, here we employ the electrode-embedded microchannels and cross-linkable double emulsions to realize construction of pixel structures, packaging of liquids and actuation of EWOD on a single microfluidic chip. We investigated thermally curable PDMS and photo-curable MD700 as the outer continuous phase, along with the middle phase, Novec 7500 or paraffin oil, and the inner phase, died water. A microfluidic device with two flow-focusing junctions was designed and fabricated to evaluate the formation of double emulsions. With appropriate hydrophobic and oleophobic coatings, the formation of water/paraffin oil/MD700 double emulsions was successful. To improve the stability of the double emulsion array, we examined the surfactants, including Pico-Surf™ and Krytox 157 FSH, and fluorinated silica for pickering emulsion in MD700. Serpentine microchannel and gradually diverging microchannels were tested to obtain the double emulsion array. 1 kHz 240 V was applied to the cross-linked double emulsion array through coplanar electrodes to generate EWOD. The coverage of the inner water droplet was observed to change from 47% in white state to 81% in dark state, with the spreading time of 240 ms and recovering time of 300 ms.
We also demonstrated a new particle-chain display with the configuration of PDMS outer continuous phase/MD700 middle phase/polystyrene particle-dispersed water inner phase double emulsions with thin shell formed with a multilayered a microchannel. By integrating parallel plate electrodes, the particles in the inner phase encapsulated by the thin shell were arranged into particle chains and changed the transmittance as a display.

並列關鍵字

microfluidics ； reflective display ； microchannel ； electrowetting-on-dielectric ； particle polarization

參考文獻

[1] L. L. Shui, R. A. Hayes, M. L. Jin, X. Zhang, P. F. Bai, A. v. d. Berg, et al., "Microfluidics for electronic paper-like displays," Lab on a Chip, vol. 14, pp. 2374–2384, Mar. 2014.

[2] M. R. Fernández, E. Z. Casanova, and I. G. Alonso, "Review of Display Technologies Focusing on Power Consumption," Sustainability, vol. 7, pp. 10854-10875, Aug. 2015.

[3] P. F. Bai, R. A. Hayes, M. Jin, L. Shui, Z. C. Yi, L. Wang, et al., "Review of Paper-Like Display Technologies," Progress In Electromagnetics Research, vol. 147, pp. 95–116, Jun. 2014.

[4] P. Gravesen, J. Branebjerg, and O. S. Jensen, "Microfluidics-a review," Journal of Micromechanics and Microengineering, vol. 3, pp. 168-182, 1993.

[5] D. J. Beebe, G. A.Mensing, and G. M.Walker, "Physics and applications of microfluidics in biology," The Annual Review of Biomedical Engineering, vol. 4, pp. 261-86, Mar. 2002.