Miniature diffusive mid-infrared photoacoustic gas sensor for carbon dioxide detection

Differential Cantilever Enhanced Fiber-Optic Photoacoustic Sensor for Diffusion Gas Detection

“…Photoacoustic (PA) spectroscopy (PAS) based gas detection technology has played a critical role in industrial fields. − Compared with other spectral detection technologies, such as tunable diode laser absorption spectroscopy, Raman spectroscopy, PAS has the peculiarities of background free, high sensitivity, and compact size. − The principle of the PAS gas detection is that target gas selectively absorbs light energy, causing the surrounding gas to expand and contract periodically, which is manifested in the form of PA pressure waves. − Consequently, the sensitivity of the acoustically sensitive components is the core factor that determines the detection index of sensing systems. By selecting high-sensitivity acoustic wave sensitive components, the detection indicators of the PA gas sensor can be effectively improved. − However, the higher sensitivity of the system is also accompanied by a decrease in the stability.…”

Rapid Photoacoustic Exhaust Gas Analyzer for Simultaneous Measurement of Nitrogen Dioxide and Sulfur Dioxide

“…Photoacoustic (PA) spectroscopy (PAS) is one of the most promising trace gas detection methods. − Compared with the normal detection methods, PAS has the advantage of fast response, low interference, high sensitivity, and portability. − At present, many PAS systems have been proposed for the detection of SO 2 and NO 2 . The usual exciting sources of PA signal are quantum cascade laser (QCL), − distributed feedback (DFB) laser, − light-emitting diode (LED), , laser diode (LD) − and infrared thermal radiation source. − For SO 2 detection, QCL can operate at the fundamental absorption bands of the SO 2 molecule. Because of the strong absorption of the molecules and the high power of QCL, a brilliant minimum detection limit can be achieved .…”