This paper presents a technique for the low-cost fabrication of plasmonic fiber-optic based refractive-index sensors. The Microsphere Photolithography (MPL) technique was used to pattern nanoholes in a thin aluminum film to create Extraordinary Optical Transmission (EOT) based sensors on the cleaved tip of SMF-28 optical fibers. This technique uses self-assembled microspheres as an optical element and facilitates very low-cost patterning of the plasmonic probes. As the refractive index of the media changes, the reflected spectrum of optical fiber changes. The fabricated sensors were immersed in water with different concentrations of glucose, and the lowest detection limit was found to be 33 mg/mL.