A novel double-tuning fork acoustic detection module for photoacoustic wide range sensing

The extension of the detection range is a crucial task for improving the effectiveness of gas sensors. In this work we propose a novel approach in quartz-enhanced photoacoustic detection in which the detection module is composed of a bare 15 kHz custom tuning fork (QTF), aligned with a 12 kHz QTF and mounted inside a vacuum-tight cell. This configuration allows the same molecule to be detected by the bare QTF at high concentration and by the 12 kHz QTF down to part-per-billion scale. The signal from the bare QTF is also useful to gather information on the gas matrix variation.