An optical and hybrid integrated sensor based on the Vernier effect principle and implemented with porous silicon and polymer waveguides is studied to detect low concentrations of biomarkers such as Bovine Serum Albumin (BSA). The principle of the Vernier effect integrated sensor adopted consists of a reference micro-resonator (MR) cascaded to another MR, the sensing MR, which is sensitive to analyte concentration. Waveguides based on porous silicon material are used to constitute this sensing MR transducer in the part of the sensor where BSA molecules are grafted to benefit from its large specific surface and its high surface sensitivity. The other parts of the sensor including the reference MR are constituted by low loss polymer waveguides. The presentation will focus on the theoretical study and the 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 a 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 implemented with bulk materials.