Here we propose optofluidic spherical microlenses that can change their focal distance by varying therefractive index of the liquid that composes them. These lenses are fabricated in the bulk of a polymericmixture. Results of a characterization study of the profile of the lenses, the image forming capability,and the behavior of the focal distance as a function of the refractive index are presented. Ionic liquidsare suggested as a source of liquids useful for fabricating this type of lens. © 2009 Optical Societyof America