[en] Surface Plasmons Resonance (SPR) architectures based on grating coupler/disperser combination is an attractive alternative for spectral-based sensing. We present a new concept where the plasmon coupling occurs through thin film grating and sensing occurs via the first diffraction order in reflective or transmitive mode. The developed geometry is dedicated to droplet sensing. The extension of the architecture to bi-dimensional array of sensors is also facilitated. This paper describes several designs of sensors. The analysis of their theoretical performances is demonstrated and compared, including a sensitivity evaluation.