Development of compact and innovative optical sensors for trace gas detection

Trace gas sensing is crucial in several application fields. In this thesis, Quartz Enhanced Photoacoustic Spectroscopy (QEPAS)-based sensors were studied, designed and employed to detect gas traces. Quartz Tuning Forks (QTFs) are employed as transducers in this sensing technique. Studies of electrical, mechanical and resonance characteristics of QTFs allowed improvements of QEPAS sensors performances. These innovative sensors were employed to both monitor the presence of pollutants in air and control the quality of mechanical components. Different detection strategies to detect multiple gas traces in mixtures were investigated. Finally, the design of a Semi-Integrated QEPAS sensor is described. The research activity related to the Industrial Ph.D. Program and presented in this thesis was carried out within the framework of PON RI 2014-2020 “Dottorato di Ricerca a Caratterizzazione Industriale” (DOT130W083), and in collaboration with two industries, i.e., MASMEC S.p.a. (Italy) and THORLABS GmbH (Germany).