Parallel dual tuning forks for quartz-enhanced photoacoustic spectroscopy

Abstract

A recently introduced approach to photoacoustic detection of trace gases utilizing dual quartz tuning forks (D-QTFs) in parallel is described in detail. It investigates the sound vibration mode that is optimal for a small acoustic module. The acoustic module was optimized using COMSOL multiphysics software. The D-QTFs sensor and a half-size resonator module platform were adopted to enhance signal strength. The advantages of the technique compared to the normal QEPAS sensor are that it uses a single resonator tube but realises a 1.25-times signal enhancement. Water vapour was chosen as the target analyte. The achieved noise of 1σ is 1.268 µV compared to the QEPAS noise of 1.196 µV. The presence of parallel forks leads to a decrease in reaction time of ∼17 %. The results of this investigation revealed that a reduced chamber volume and rapid response led to a more pronounced signal response. The sensor's performance can be further enhanced by increasing the laser power and the optical path length. It is widely used in fields with volume constraints.