In this paper, a micro-opto-mechanical polymeric cantilever based Fabry Perot Interferometer(CFPI) is reported as an optical fiber sensor. To be able to fabricate the sensor, a mold for the polymeric cantilever was fabricated using poly methyl methacrylate (PMMA) and with which a polydimethylsiloxane (PDMS) cantilever was constructed. After releasing the cantilever from the mold, cantilever and SMF were integrated together. As a result, a cavity was formed between SMF cleaved end and cantilever surface. When vibration is applied, the distance between the cantilever free end and cleaved end SMF changes, consequently the optical patch length of the sensor structure altered dynamically. Here, the effect of different frequencies and their amplitudes on the sensor spectrum is studied by using FFT and STFT analysis method.