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 In this study, we developed a varifocal liquid-filled microlens, of which operational principle is illustrated in Fig. 1. The focal length of the microlens varies along with the deformation of a transparent elastomer membrane under hydraulic pressure tailored by EAP actuators. The main structure of the microlens is composed of a glass frame and a micromachined silicon frame. The latter has a lens hole and four microfluidic chambers. The lens hole has a circular shape so that the elastomer membrane clamped on the lens hole serves as an axisymmetrically, but non-spherically, deformable membrane lens. The silicon and glass frames are bonded together to form microfluidic channels connecting the chambers and lens. The top surface of the silicon frame is covered with a transparent elastomer membrane, and the internal volume confined by the membrane and the two frames are filled with optical fluid with a high refractive index. A sheet of EAP actuator is attached to some portion of the elastomer membrane so that the actuator together with the elastomer membrane forms a bimorph actuator to produce bending deformation under an applied electric field. The bimorph actuator pushes the optical fluid in the microfluidic chamber into the lens part, which in turn changes the shape of the transparent elastomer membrane. The shape change of the membrane at this point corresponds to the change of the focal length.