A Fabry-Pérot microcavity tip sensor fabricated by post-processing of a special designed double-cladding optical fiber is proposed. The produced fiber has a pure silica core and outer cladding and an inner silica cladding surrounding the core doped with phosphorous. When subjected to chemical etching post-processing, the whole ring region is removed and light is guided in the core region. The sensing head is created simply by splicing this fiber to single mode fiber and applying chemical etching to the fiber end. The core is forming a tip and is thus surrounded by air. The Fabry-Pérot microcavity tip sensor is subjected to temperature, and a sensitivity of 15.5 pm/ºC is obtained.