Design, Fabrication and Measurement of Contact Lens with Capacitive Sensor for Evaporation Rate

• Main Authors: Dai, Kai-shiun, 戴凱勛
• Other Authors: Chiou, Jin-chern
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/26779746970806685540

碩士 === 國立交通大學 === 電機工程學系 === 105 === 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.