Compact and Highly Sensitive NO2 Photoacoustic Sensor for Environmental Monitoring

Abstract

A nitrogen dioxide (NO2) photoacoustic sensor for environmental monitoring was developed using a low-cost high-power laser diode emitting at 450 nm. A compact low-noise photoacoustic detection module was designed to reduce the sensor size and to suppress noise. A LabVIEW-based control system was employed for the sensor. The parameters of the sensor were studied in detail in terms of laser power and operating pressure. The linearity of the sensor response with laser power and NO2 concentration confirms that saturation does not occur. At atmospheric pressure, a 3σ detection limit of 250 ppt (part per trillion by volume) was achieved with a 1-s averaging time, which corresponds to the specific detectivity of 3.173 × 10−9 W cm−1 Hz−1/2. A 72 h outdoor continuous on-line monitoring of environmental NO2 was implemented to demonstrate the reliability and validity of the developed NO2 sensor.

Application of the Photoacoustic Approach in the Characterization of Nanostructured Materials

“…However, some specificity of the signal formation should be considered to distinguish the optical properties of the considered media with good precision. A typical application of PA spectroscopy is the detection of atmospheric CH 4 , CO 2 [107] ppm, NO 2 [108], and N 2 O, and sensitivity in the range of a few parts per billion could be achieved [109]. For further insight regarding PA gas sensing, one can refer to the recent reviews [2,105,106].…”

“…A typical application of PA spectroscopy is the detection of atmospheric CH4, CO [107] ppm, NO2 [108], and N2O, and sensitivity in the range of a few parts per billion coul be achieved [109]. For further insight regarding PA gas sensing, one can refer to the recen reviews [2,105,106].…”

Photoacoustic-Based Gas Sensing: A Review

“…Nitrogen Dioxide (NO 2 ) LD [108][109][110][111][112] Multimode LD [113] LED [114][115][116][117][118] Nitric Oxide (N 2 O) QCL [112,119] OPO [120] Nitrogen oxide (NO) QCL [121] LD [122] Ammonia (NH 3 ) QCL [123][124][125] CO 2 laser [126,127] LD [128] Carbon Dioxide (CO 2 ) QCL [129] CO 2 laser [130] LD [131][132][133][134] OPO [135] Table 2. Cont.…”

Ultra-sensitive ppb-level methane detection based on NIR all-optical photoacoustic spectroscopy by using differential fiber-optic microphones with gold-chromium composite nanomembrane

“…Beyond conventional methods such as electro-chemistry and gas chromatography [5] , [6] , optical methods allow improved selectivity and sensitivity as well as fast response. Optical methods using laser absorption spectroscopy (LAS) based on the ‘finger-print’ absorption lines of molecules, such as tunable diode laser absorption spectroscopy (TDLAS), cavity ring-down spectroscopy (CRDS) and photoacoustic spectroscopy (PAS) [7] , [8] , [9] , [10] , have been widely investigated for trace gas detection. TDLAS-based sensors have been widely commercialized [11] , and it fundamentally relies on the long optical path and superior photodetectors to achieve favorable sensing performance.…”