Variable Focal Length Microlens by Low Voltage Electrowetting on Dielectric (EWOD) Actuation

This work presents a design and proposed microfabrication steps for a two-liquid variable focal length capillary microlens. The capillary lens is actuated by electrowetting on dielectric effect. The microlens is made from a dielectric liquid whereas a conducting liquid serves as one of the electrodes for the actuation. The dependence of the microlens focal length on the properties of the dielectric materials is investigated using a model for electrowetting on dielectric effect. The model indicates that low voltage actuation (<20V) is possible by adjusting the dielectric layer thickness. The effect of the microlens size on the focal length is presented. The advantages of a two-liquid capillary microlens are briefly discussed.