Miniaturization of Dielectric Liquid Lens

介電液態透鏡微小化研究

楊志誠(Chih-Cheng Yang)

指導教授 ： 葉哲良

國立清華大學/工學院/奈米工程與微系統研究所/博士(2011年)

https://doi.org/10.6843/NTHU.2011.00348

摘要

The aperture diameter of tunable focus liquid lenses usually falls in a range of a few millimeters. Miniaturization of the liquid lenses may play a critical role on compact micro-optical systems. This study presents packaged micro-scale liquid lenses actuated with liquid droplets of 300 μm - 10 mm in diameter using the dielectric force manipulation. The liquid microlenses demonstrate functional focal length tunability in a plastic package. Characterization of a dielectric liquid microlens with a diameter of 0.3 - 10 mm was investigated. The package of the liquid microlens has potential to be integrated with another optical device for sensing applications.
This study also demonstrates on the dynamic responses of dielectric liquid microlenses via experiments and simulations using the dielectric force. The dynamic characterization of the liquid microlenses of 0.3 - 10 mm in diameter are experimentally investigated at the aspects of the contact angle over time with respect to viscosity, voltage, AC frequency and droplet size. The dependence of time constant was extracted against the four input variables. Multiphysics model was solved to obtain numerical simulation for dielectric liquid lens using COMSOL. Both the work and its result pioneer the study in this field. A first-order dynamic model was proposed to treat the dynamics of dielectric liquid lenses, of which is simplified from the second-order dynamics due to negligible inertia of two liquids with nearly identical density. The dynamic model might be a bit simple but it could provide some insights for engineering design. This work might serve as an important reference in developing a droplet-based micro-lens.

關鍵字

介電力 ； 液態透鏡 ； 接觸角 ； 動態響應

並列摘要

發展中的液態透鏡的光圈直徑通常是設計在數毫米的範圍中。因此如何微小化液體透鏡，未來於微光學系統應用發展中，將扮演一個重要關鍵性角色。本文研究直徑大小介於三百微米至十毫米的介電式微液態透鏡，並將介電式液態透鏡設計密封在一個塑膠外殼中，使其具有可攜性及焦距可調整的功能。由於此封裝後的微液態透鏡之可攜性提高，將具有與其它光學微感測元件整合應用的潛力。在建立各種基本特性量測實驗中，介電式微液態透鏡的光學、靜態性質與動態特性，在研究中逐步被實驗調查。
本論文並建立了一個以有限元素軟體計算與預估液態透鏡的動態行為的模擬技巧，並由實驗資料來驗證介電式微液態透鏡的動態模擬，一方面藉由實驗修正模擬軟體的相關係數，另一方面藉由模擬加速對介電式液態透鏡的驅動物理模式的進一步了解，進而降低實驗的嘗試錯誤次數。研究中以實驗調查直徑從三百微米到十毫米不同大小的介電式微液態透鏡之動態特性，特別是有關於粘度、電壓、電壓頻率和液滴大小等影響因素相對於接觸角變化及響應時間的關聯性則一一被釐清，再由動態實驗資料的歸納與整理，本論文找出粘度、電壓、電壓頻率與液滴大小等影響因素與動態時間常數相關性，並萃取分析出相對於動態響應時間常數的關係式。
藉由從量測的動態資料中歸納分析後，本論文首先提出一個一階微分的動態分析模型來對應介電式微液態透鏡的動態行為，此一階微分的動態分析模型雖然簡單，但可以用來預測粘度、頻率與液滴大小等參數對動態接觸角的影響，從分析中可以找到相關物理參數對動態特性的影響。此模型可以為往後工程設計提供一些啟發，對於發展各式各樣不同尺寸大小介電式液態透鏡，提供一個快速有效快速的預估模式與設計參考基礎。

並列關鍵字

Dielectric force ； Liquid lens ； Contact angle ； Dynamic response

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