An optical fiber based polymer core sensor includes an optical fiber having a core and an end having a cured polymer core affixed to the core of the optical fiber. The cured polymer core extends outward from the end of the optical fiber and has a diameter approximately equal to the core of the optical fiber. Note the cured polymer core can be substantially cylindrical, tapered or geometrically shaped. The optical fiber based polymer core sensor can be used to measure a temperature, measure a strain, measure a distance, measure a refractive index, detect or measure an analyte, detect a toxin, detect a biological agent, monitor a chemical process, or a combination thereof