In oil and gas exploration and environmental monitoring fields is extremely important to rely on versatile and rugged trace gas sensors that can be mounted on remote-controlled unmanned vehicles to monitor dangerous areas inaccessible to a human operator. Thereby, a compact fiber-coupled dual-gas QEPAS sensor employing a custom tuning fork was designed and tested. Two distributed feedback pigtailed diode lasers emitting at 1654 nm and 1684 nm, for methane and ethane detection respectively, were also employed. The gas sensor was calibrated for ethane and methane trace detection and a minimum detection level of 18 parts per million and 570 parts per billion at 1 s integration time were respectively achieved. Methane detection in atmosphere was also performed.
We report on the development of a gas sensor system based on quartz-enhanced photoacoustic spectroscopy (QEPAS) for the detection of trace levels of ethylene using a quantum cascade laser operating at ~ 10.3 μm. To realize a compact sensor architecture, a dedicated acoustic detection module was designed and implemented. The module includes a QEPAS spectrophone, composed of a quartz tuning fork, a micro-resonator tube and a low-noise pre-amplifier chip for the signal readout. The volume of the ADM is ~30 cm3. A minimum detection limit of 30 part-per-billion in concentration was obtained with a data acquisition time of 10 s.