Methane and carbon dioxide mixed gas detection based on sphere–tube coupled photoacoustic cell

Compact gas cell for simultaneous detection of atmospheric aerosol optical properties based on photoacoustic spectroscopy and integrating sphere scattering enhancement

“…Notably, the acoustic pressure peaks at the resonance frequency corresponding to the second resonance mode, specifically at 1258 Hz, reaching approximately 5.4 × 10 −5 Pa. Under identical simulation conditions, the acoustic pressure amplitude of the DTPAC surpasses that of both the sphere-tube coupled photoacoustic cell (2 ×10 −6 Pa) [40] and the H-type differential photoacoustic cell (3 ×10 −5 Pa) designed in our previous work [41] . In comparison with recently reported innovative photoacoustic cells, such as the differential integrating sphere photoacoustic cell (1.1 ×10 −6 Pa) [25] and the novel T-type photoacoustic cell (1.2 ∼ 6 ×10 −5 Pa) [23] , the DTPAC maintains a competitive edge in terms of acoustic pressure amplitude.…”

Optical Fiber‐Based Gas Sensing for Early Warning of Thermal Runaway in Lithium‐Ion Batteries

“…The mostly used acoustic sensor is still microphone, which is cheap and mature for vibration detection. In a recent work, [73] a sphere-tube coupled PA cell was designed to enhance the response of CO 2 with a 2004 nm distributed feedback (DFB) laser, which showed a LOD of 23 ppm in 5 s. In a similar work, [74] a sphere PA cell with multi-resonance property was designed, and the location of microphone for achieving maximum response has been theoretically simulated and verified by experiment, in which 767 ppm CO 2 can be detected in 1 s. For all-optical photoacoustic sensing, 2.4 ppm in 1 s and 318 ppb in 116 s have been achieved by quartzenhanced PA cell based on a tuning fork. [75] Besides, based on a FP pressure sensor and a digital virtual lock-in amplifier, a low LOD of 60 ppb CO 2 has been realized within 100 s. [76]…”

“…Similar to CO 2 sensing by PAS, actually, in most multi-gas PAS sensing cases, CH 4 as a co-existed gas is detected with CO 2 simultaneously. In the above works introduced in the CO 2 sensing part, the LOD of CH 4 has been reported as 509 ppb in 5 s, [73] 69.2 ppm in 1 s, [74] and 37 ppb in 100 s, [76] respectively.…”

Flexible Hollow Core Fiber Photoacoustic Gas Sensor Based on Embedded Acoustic Resonant Structure

“…This should be attributed to the low transmission loss and the satisfactory flexibility of the LHCF. It should be noted that the amplitude of the PA signal A has a relationship with the V−T relaxation time of the detected gas molecule, which is shown in eq 4 44 (4) where f is the operation frequency of a PA gas sensor, and τ is the V−T relaxation time of the gas molecule. If the proposed sensor was used to detect gases with a long V−T relaxation time in the future, such as CO 2 and carbon monoxide (CO), a low operation frequency could be much more proper.…”

“…Resonant photoacoustic (PA) gas sensors have been extensively studied because of their outstanding sensitivity over that of the non-resonant PA gas sensors. − The resonant PA gas sensors are hence being applied in many fields in human daily life. − …”