Smart self-cleaning cover glass for automotive miniature cameras

• Published in: 2016 IEEE 29th International Conference on Micro Electro Mechanical Systems (MEMS) pp. 83 - 86
• Main Authors: Kang Yong Lee, Jiwoo Hong, Dea Sung Jang, Sung Jin Hong, Sang Joon Lee, Sang Kug Chung
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01.01.2016
• Subjects: Cameras; Decision support systems; Electric potential; Electrodes; Glass; Micromechanical devices; Transportation
• DOI: 10.1109/MEMSYS.2016.7421563

We systematically study removal of sessile and pendant droplets with different volumes on an inclined plane tilted at various angles as well as on a horizontal plane by electrowetting (EW) actuation. In absence of an applied voltage, sliding angles (i.e., the minimum inclination angle for the onset of the sliding motion) are experimentally measured as a function of droplet volume. In addition, threshold voltages (i.e., the minimum electrical voltage for the onset of the sliding motion) of sliding droplets are found with respect to different droplet volumes and inclination angles when DC voltages are sequentially applied to the electrodes. The threshold voltage is found to decrease as the droplet volume and inclination angle increase because of the increase in gravitational force. Furthermore, we show that AC EW can be employed to remove droplets on inclined planes, because AC EW-driven interfacial oscillation helps overcome the pinning force caused by contact angle hysteresis. Finally, based on these results, we design a smart self-cleaning cover glass for miniature cameras assisted by EW. It can remove water droplets in a wide range of sizes to allow the camera's lens to get clean at any time. The proposed cover glass can perform a fast cleaning operation with effective energy consumption as well as can be easily integrated onto any device due to its simple design structure.