基於兩相流體在孔徑處形變利用水和 PDMS 製作 透鏡之研究

Abstract

隨著智慧型手機的普及和成本下降，其在全球人口的社會滲透率不斷增加。促進了智慧手機作為現場醫療診斷設備，感測器和可擕式數位顯微鏡等非傳統使用技術的發展。現有的使用平行模具衝壓和高溫回流的低成本透鏡的方法需要複雜的工程控制以生產高品質透鏡。這些製造技術依賴昂貴的設備。在本論文中，我們提出一個適用於結合智慧型手機鏡頭的平凸透鏡製作方法。我們利用兩相流體在固定孔徑處的表面張力，並通過控制水和二甲基矽氧烷（PDMS）體積變化，而製作出可重複使用的正球型透鏡模具。此乃採用通過對水在孔徑處溢出的體積變化使得模具曲率發生變化，之後在固化後的PDMS模具中的膜腔處填充UV固化材質NOA65，便可以在25分鐘內製作出相同透鏡，其焦距在1.75-3.88mm之間。以此方法來製作透鏡，不僅製作方法簡單，且成本低、效率高，不像現有的製作方式，使用平行模具衝壓和高溫回流，此種須昂貴設備的透鏡製作方法，則需要複雜的工程控制，得以生產高品質透鏡。使用這些鏡頭，我們能夠將普通的智慧型手機相機轉變成一個低成本的數字皮膚電圖儀和可擕式紙鈔辨識裝置，用以觀察皮膚上和紙鈔上的微觀結構。

With the reducing cost of smartphones and their popularity among people, their social penetration continues to increase, driving the development of non traditional technologies for on-site medical diagnostic devices, sensors and portable digital microscopes. Existing methods of using low cost lenses made with parallel stamping and high temperature require complex engineering controls to produce high quality lenses. These manufacturing techniques rely heavily on expensive equipment. In this paper, a method of making a plano-convex lens suitable for the conjunction with a smart phone lens is proposed. We make use of the surface tension of the two-phase fluid at the fixed pore and control the volume change of water and dimethylsiloxane (PDMS) to produce a reusable positive spherical lens mold. This is achieved by the changing of radius of curvature through the overflow volume change of water at the pore, then filling the UV curing material NOA 65 in the film cavity in the cured PDMS mold. In 25 minutes, the same lens with 1.75-3.88mm focal length can be produced with lower cost and higher efficiency. In contrast, current methods require parallel stamping and high temperature equipment. Such method with expensive equipment also requires complex engineering controls in order to produce high quality lenses. By using the proposed lenses, we are able to turn a conventional smart phone camera into a low-cost digital skin electrograph and portable paper money identification device to observe the microstructures, such as the skin or the banknotes.