An optical and hybrid integrated sensor based on Vernier effect principle and implemented with porous silicon and polymer waveguides is studied to detect low concentration of biomarkers such as Bovin Serum Albumin (BSA). Vernier effect integrated sensor consists of an integrated interferometer micro-resonator (MR) as a reference, cascaded to another integrated interferometer which is sensitive to analyte concentration. In our case two MR are cascaded: a porous silicon MR is used in the part of the sensor where BSA molecules are grafted to benefit from its large specific surface and, its high surfacic sensitivity. Moreover, low propagation losses polymer waveguides are used for the reference part of the structure. The presentation will focus on theoretical study and design of the sensor, particularly on the evanescent coupling between porous silicon and polymer waveguides. Then, the fabrication of the sensor, using standard photolithography will be detailed. Moreover, characterization on optical bench and comparison to theoretical results will be presented. This hybrid Vernier effect based sensor demonstrates a theoretical Limit Of Detection (LOD) of 0.019 pg.mm-2 and sensitivity of 12.5 nm/(pg.mm-2). To our knowledge, these values are 8 times lower for the LOD and 200 times higher for the sensitivity compared to the state of the art of Vernier effect biosensors.