電容式隱形眼鏡蒸散感測器之設計、製作與量測

Abstract

本研究提出一個以微機電製程技術製作可與隱形眼鏡整合且具可撓性之電容式感測元件。元件皆使用生物相容性良好的材料，如使用透明的聚一氯對二甲苯(Parylene C)作為基材與絕緣層，金作為電容之電極，並使用反應式離子蝕刻系統(RIE)定義出電極間間隙結構，以利於感濕材料聚羥乙基異丁稀酸酯(Polyhydroxyethyl methacrylate)填入電極間間隙，同時將感測元件與隱形眼鏡進行整合，整合後表面平順且無皺褶產生。電容式感測器的優點為線性度高、重現性高、靈敏度高且特性不會隨時間改變。主要感測原理為利用高分子材料吸水特性與釋放特性，使感濕材料介電係數產生改變進而改變電容值。 在感測器特性量測上分為兩階段，第一階段先利用環境溫濕度的改變，間接改變蒸散速度，證實感測器的可行性。藉由第一階段的實驗，了解到環境溫濕度對感測器的影響。第二階段利用去離子水與兩種不同的人工淚液對感測器進行測試，結果顯示當量測的溶液不同時，感測器會有不同的特性，溶液隨時間蒸散時，感測器之電容變化也能反映出蒸散速度的不同，且具有相當好的重現性與線性度(R2 ≧0.9)。

The purpose of this thesis is to provide the use of MEMS manufacturing technology to fabricate a flexible capacitor evaporation sensor which can be integrated with contact lens. All materials of the element are biocompatible. The transparent layer of parylene C is used as substrate and electrical insulation. The capacitor is fabricated using the gold layer and using reactive ion etching system etches the insulating layer between the electrodes. The contact lens material of Polyhydroxyethyl methacrylate as moisture-sensitive material is filled into the gap between the electrodes, while the sensing element is combined with contact lens. The contact lens is smooth and without wrinkle. Advantages of capacitive sensor are high linearity, reproducibility, high sensitivity, and characteristic does not change over time. The main sensing principle is based on the change of dielectric constant after the moisture-sensitive material absorbing or releasing water molecule. By changing the dielectric constant of the moisture-sensitive material, the capacitance value of sensor will change. First, by changing the temperature and humidity, indirectly changing evaporation rate, we confirm the feasibility of sensors. Meanwhile, we understand that environment can cause a great impact to sensors. Second, Using DI water and two different artificial tear to test the characteristic of sensors. When using different solution, the characteristic of capacitance will change. The results show that the sensor has good reproducibility and responding speed.