A variable-focus lens assembly is provided. The lens assembly includes a microfluidic device that defines a chamber for receiving a fluid therein. A slip having an aperture therethrough is disposed in the chamber. A first fluid is disposed on the first side of the slip and a second fluid is disposed on the second side of the slip. A lens is formed from the interface of the first and second fluids. The outer periphery is pinned to the slip about the aperture. A turning structure fabricated from a hydrogel material engages the slip and tunes the focal length of the lens in response to a predetermined stimulus.