Abstract
A lens device with an adjustable focal length is provided. The lens device includes a non-conductive liquid droplet, which is surrounded by air or immiscible liquids. The non-conductive liquid droplet is placed on a bottom plate. The bottom plate includes a set of first electrodes. The set of first electrodes is disposed in such a way that the set of first electrodes are capable of being selectively biased to respectively create a first voltage potential difference between the liquid droplet and each of the set of first electrodes. With the first voltage potential differences, a dielectric force is induced, and the profile of the non-conductive liquid droplet is adjustable. Thus, the focal length of the lens is adjustable.