Electrowetting is a microfluidic phenomena which involves modifying the surface tension of liquids on a solid surface using a voltage. By applying a voltage, the wetting properties of a hydrophobic surface can be modified and the surface becomes increasingly hydrophilic (wettable).
Electrowetting is currently being used for a wide range of fluidic and electro-optic applications. With Electrowetting displays, the modification of the surface tension is used to obtain a simple optical switch by contracting a colored oil film electrically. Without a voltage, the colored oil forms a continuous film and the color is visible to the consumer. When a voltage is applied to the display pixel the oil is displaced and the pixel becomes transparent. When different pixels are independently activated, the display can show content like an photograph or a video.