Microelectrofluidic lens for variable curvature

Abstract

This paper presents a tunable liquid lens based on microelectrofluidic technology which integrates electrowetting and microfluidics. In the novel microelectrofluidic lens (MEFL), electrowetting in the hydrophobic surface channel induces the Laplace pressure difference between two fluidic interfaces on the lens aperture and the surface channel. Then, the pressure difference makes the lens curvature tunable. The previous electrowetting lens in which the contact angle changes at the side wall has a certain limitation of the curvature variation because of the contact angle saturation. Although the contact angle saturation also appears in the surface channel of the MEFL, the low surface channel increases the Laplace pressure and it makes the MEFL to have full variation of the optical power possible. The magnitude of the applied voltage determines the lens curvature in the analog mode MEFL as well as the electrowetting lens. Digital operation is also possible when the control electrodes of the MEFL are patterned to have an array. It is expected that the proposed MEFL is able to be widely used because of its full variation of the optical power without the use of oil and digital operation with fast response.