In the application where infinitely-variable lens without any moving parts is needed, liquid lenses are not a new thing to implement. Conventional liquid lenses use two immiscible fluids, each with a different refractive index, to create variable-focus lenses of high optical quality as small as 10 µm (microns). There are two ways to manipulate the two fluids, electrically and mechanically, but both methods take advantage of the surface tension of the liquid. The electric method uses a novel property called electrowetting (full review on electrowetting: J. Phys.: Condens. Matter, 2005, 17, R705-R774) to modify the surface tension, while the mechanical method takes advantage of surface tension to physically change the shape of the lens (more details of liquid lenses introduced by Alix Paultre).