Electrowetting-Based Liquid Iris

In this letter, we propose a liquid iris based on electrowetting. A dyed liquid is filled in a hollow cylinder cell. One substrate surface of the cell is coated with a Teflon layer. Due to the low surface tension of the Teflon, the dyed liquid forms a circular ring around the cylinder wall. The outside space of the liquid is filled with opaque oil. The opening of the circular liquid forms an aperture. When a voltage is applied to the cell, the dyed liquid shifts to the center of the ring due to electrowetting effect. Thus the aperture shrinks. Our results show that the aperture can be tuned between ~ 5.0 and ~ 2.8 mm. The device can provide reasonable response time. In the opening area, the transmittance was measured to be ~ 86%.