Abstract : We present our latest advances in the field of miniature optical particulate matter sensors. By illuminating a single particle in an air channel, one can record the light scattering signature with a CMOS image sensor and then, classify particles. This signature is pre-processed optically with an advanced, millimeter-sized, monolithic, refracto-reflective optical system. It performs notably a Fourier transform with very wide FoV of scattering angles, and includes as well integrated fluidics and alignment. Functional prototypes were fabricated using laser micro machining on glass, selective polishing, and were replicated with epoxy resin using a molding process.