We present the design of a lens for CCD or CMOS sensors using a new generation of lenses with electrically controlled focal length. These new elements made out of liquids (a drop of oil in water) work according to the principle of electro-wetting: the spreading of a drop of water on an electrically insulating surface can be modified by creating an accumulation of charges at the base of the drop. The densities of the two liquid phases are matched in order to keep the phases in place whatever the position of the lens. This new lens can be used in small devices to achieve auto-focus camera modules. There are several ways to integrate our adaptive optic in a fixed camera module lens, classically made up of plastic lenses. We will discuss three different configurations for a VGA system with 4 mm focal length, f/3 aperture, 60° field. The optical resolution is excellent, for object distance going from 50 mm to infinity.