In the last decades, metallic nanostructures have played a key role in biosensing, as they exhibit unique properties that make them excellent optical transducers. In this work, we show the combination of hybrid plasmonic/dielectric materials to significantly improve the sensitivity of large-scale plasmonic arrays. Precisely, we propose the optimization of the fabrication process of the Gold Nanomushrooms by substituting the pillar with dielectric Silicon Nitride, to obtain a sensor with a high sensitivity to refractive index variation, for biomedical applications.