Spectral Sensing Using a Handheld NIR Module Based on a Fully Integrated Sensor Chip

Abstract

Near-infrared (NIR) spectroscopy is widely used for the classification of materials and the quantification of their properties. Today, there is a high demand for extending the use of this technique to portable appli-cations, and eventually, the integra-tion with consumer appliances and smartphones. To reach this goal, the overall size of the NIR sensor, its pro-duction cost, robustness, and resis-tance to vibrations are of particular importance. This paper describes an approach to spectral sensing in the NIR (850–1700 nm) using a hand-held sensor module based on a fully integrated multipixel detector array with a footprint of around 2×2 mm2 . The capabilities of the spectral sensor module were recently evaluated in two application cases: Quantifica-tion of the fat percentage in raw milk and the classification of plastic types. Fat quantification was achieved with a root mean square error (RMSE) of prediction of 0.14% and classification of plastic types was achieved with a prediction accuracy on unknown samples of 100%. The results demon-strate the feasibility of the direct NIR sensing approach used by the integrated sensor, which has potential to be used in a variety of applications.