Photoacoustic spectroscopy for gas sensing: A comparison between piezoelectric and interferometric readout in custom quartz tuning forks

• Published in: Photoacoustics (Munich) Vol. 17; p. 100155
• Main Authors: Dello Russo, Stefano, Zhou, Sheng, Zifarelli, Andrea, Patimisco, Pietro, Sampaolo, Angelo, Giglio, Marilena, Iannuzzi, Davide, Spagnolo, Vincenzo
• Format: Journal Article
• Language: English
• Published: Germany Elsevier GmbH 01.03.2020; Elsevier
• Subjects: Gas sensing; Interferometry; Photoacoustic spectroscopy; Piezoelectricity; Tuning fork; Piezoelectricity; Gas sensing; Photoacoustic spectroscopy; Tuning fork; Interferometry
• ISSN: 2213-5979; 2213-5979
• DOI: 10.1016/j.pacs.2019.100155

We report on a comparison between piezoelectric and interferometric readouts of vibrations in quartz tuning forks (QTFs) when acting as sound wave transducers in a quartz-enhanced photoacoustic setup (QEPAS) for trace gas detection. A theoretical model relating the prong vibration amplitude with the QTF prong sizes and electrical resistance is proposed. To compare interferometric and piezoelectric readouts, two QTFs have been selected; a tuning fork with rectangular-shape of the prongs, having a resonance frequency of 3.4 kHz and a quality-factor of 4,000, and a QTF with prong having a T-shape characterized by a resonance frequency of 12.4 kHz with a quality-factor of 15,000. Comparison between the interferometric and piezoelectric readouts were performed by using both QTFs in a QEPAS sensor setup for water vapor detection. We demonstrated that the QTF geometry can be properly designed to enhance the signal from a specific readout mode.