A Planar Liquid Lens Design Based on Electrowetting

In this paper, a planar liquid lens is designed and implemented based on competitive electro wetting. A droplet of silicone oil confined in an aqueous solution works as a liquid lens. Electro wetting then controls the shape of the confined silicone oil and the focal length of a liquid lens varies depending upon an applied electric potential. A ring-type planar electrode successfully confined a droplet of silicone oil in an aqueous solution by electro wetting. With an external DC voltage applied in the range of 0-200 V, the confined silicone oil droplet changed its shape. Using the liquid lens, optical magnification was demonstrated and the focal length change of the liquid lens was characterized. The focal length varied from 12 mm to 22 mm with a 3 mm-diameter liquid lens. The demonstrated liquid lens has a simple structure and is easy to fabricate. The planar structure envisages an integrated optical system for lab-on-a-chip applications.