Plastic sorting with an integrated NIR spectral sensor

Near-infrared spectroscopy (NIR) is widely used today in applications ranging from monitoring industrial manufacturing processes to assessing the chemical composition and quality of products and materials. However, the challenge remains in reducing size and cost of these spectroscopic devices, while maintaining their sensitivity and robustness. The miniaturisation of spectral sensors is essential to expanding their application beyond dedicated stations in industrial settings and analytical labs, into the hands of non-specialists working on-site and eventually to consumers. The design of current portable NIR sensor systems is mostly inspired by conventional instruments that use gratings or interferometers. The drawback of these approaches is that they are complex to assemble and contain movable parts that are susceptible to shocks and mechanical vibrations.