Fabry Perot interferometric sensor for gas detection

S. ORTIZ; C. RINALDI; C. TORO; M. BELLINO; C. FERRARI; J. BONAPARTE; A. LAMAGNA

Congreso; 15th International Meeting on Chemical Sensors; 2014

In this work, we present an optical sensor based on Fabry Perot (FP) interferometry, for characterization of gas samples contained in, or flowing through, millimeter-sized cells. Sensors were made by coating a thin nanostructured layer of metal dioxides (e.g., SiO2, TiO2) on silicon wafers. Interference results from multiple reflections originated at air-layer and the layer-silicon interfaces, leading to circular fringes that are captured by a CMOSsensor near the focal distance of a convergent lens. The presence and amount of analyte in the cells produce measurable shifts in the interferometric fringes. These shifts are related to variations in the refraction index and depth of the thin layers, which can be estimated by a simple geometric model. Here, we show our first experimental results, relate them to theoretical models for chemical adsorption on thin layers, and discuss future lines of research leading to fast-response, versatile detectors.