Damping Mechanisms of Piezoelectric Quartz Tuning Forks Employed in Photoacoustic Spectroscopy for Trace Gas Sensing

Abstract

A study of the dependence of main loss mechanisms on the geometry of piezoelectric quartz tuning forks (QTFs) is reported. The influence of these loss mechanisms on the quality factor Q occurring while the QTF vibrates at the in‐plane flexural fundamental and first overtone resonance modes is investigated. From this study, two QTFs efficiently operating both at the fundamental and first overtone mode are designed and realized. Data analysis demonstrates that air viscous damping is the dominant energy dissipation mechanism for both flexural modes. However, at the first overtone mode the air damping is reduced and higher quality factors can be obtained when operating at the first overtone mode with respect to the fundamental one.

Acoustic Coupling between Resonator Tubes in Quartz-Enhanced Photoacoustic Spectrophones Employing a Large Prong Spacing Tuning Fork

“…For a shorter distance, x = 400 µm, the QTF signal was reduced. This drop was not predicted by the theoretical model but can be explained by considering that when tubes are too close to the QTF, they generate a damping of QTF vibrations, causing an overall quality factor decreasing that negatively affects the QTF signal [19,20]. At distances larger than 5 mm, the sound energy transfer between the tubes was highly reduced; therefore, these distances are not feasible for QEPAS sensing.…”

Quartz-Enhanced Photoacoustic Detection of Ethane in the Near-IR Exploiting a Highly Performant Spectrophone

“…The resonance peak broadening is proportional to the energy losses occurring in the vibrating prongs. Furthermore, the larger the broadening, the higher the losses [40]. The quality factor Q was calculated as the ratio between the resonance frequency and the full-width-half-maximum (FWHM) value of the resonance curve.…”

“…Extremely robust and reliable QEPAS sensors implementing standard QTF-based acoustic detection modules (ADM) were demonstrated in literature [23,24] and tested in real world applications [25], and also exploiting the single-mode beam delivery provided by optical fibers in the mid-IR [26,27]. Targeted applications were leak detection [28], hydrocarbon detection [29], and environmental monitoring [30,31].Starting from 2013, several studies have been performed to design QTFs with custom geometries optimized for QEPAS sensing [20,21,[32][33][34][35][36][37][38][39][40][41]]. An extensive investigation correlated the resonance frequency and the quality factor of the fundamental mode of the QTF with the prong sizes and geometry.…”

“…Starting from 2013, several studies have been performed to design QTFs with custom geometries optimized for QEPAS sensing [20,21,[32][33][34][35][36][37][38][39][40][41]]. An extensive investigation correlated the resonance frequency and the quality factor of the fundamental mode of the QTF with the prong sizes and geometry.…”

Influence of Tuning Fork Resonance Properties on Quartz-Enhanced Photoacoustic Spectroscopy Performance

“…The main contributions are due to the damping by the surrounding fluid, the interaction of the prong with its support and thermo-elastic damping. All these loss mechanisms strongly depend on the QTF prongs’ size [25,26]. Hence, the quality factor will depend on the prong geometry, as well as the fundamental resonance frequency.…”