Results 31 to 40 of about 825 (180)

Off-Beam Acoustic Micro-Resonator for QEPAS Sensor with a Custom Quartz Tuning Fork

Atmosphere
Quartz-enhanced photoacoustic spectroscopy (QEPAS) has shown great promise for monitoring greenhouse gases and pollutants with a high measurement accuracy and limit of detection.
Yong Wang, Gang Wang, Jiapeng Wang, Chaofan Feng, Qingyuan Tian, Yifan Chen, Ruyue Cui, Hongpeng Wu, Lei Dong   +8 more
doaj   +2 more sources

Quartz Enhanced Photoacoustic Spectroscopy on Solid Samples [PDF]

Sensors
Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) is a technique in which the sound wave is detected by a quartz tuning fork (QTF). It enables particularly high specificity with respect to the excitation frequency and is well known for an ...
Judith Falkhofen, Marc-Simon Bahr, Bernd Baumann, Marcus Wolff   +3 more
doaj   +2 more sources

Sub-ppb level HCN photoacoustic sensor employing dual-tube resonator enhanced clamp-type tuning fork and U-net neural network noise filter [PDF]

Photoacoustics
Hydrogen cyanide (HCN) is a toxic industrial chemical, necessitating low-level detection capabilities for safety and environmental monitoring. This study introduces a novel approach for detecting hydrogen cyanide (HCN) using a clamp-type custom quartz ...
Lihao Wang, Haohua Lv, Yaohong Zhao, Chenglong Wang, Huijian Luo, Haoyang Lin, Jiabao Xie, Wenguo Zhu, Yongchun Zhong, Bin Liu, Jianhui Yu, Huadan Zheng   +11 more
doaj   +2 more sources

Research on the real-time measurement system based on QEPAS

Wuli Xuebao/Acta Physica Sinica, 2012
A real-time measurement of gases based on QEPAS is introduced. For eliminating fluctuation of laser, a simple method, in which a digital PID algorithm and a software lock-in amplifier designed by using Lab-VIEW are employed, is utilized to lock the laser to the center of the absorption line.
Tan Tu, Zhang Wei-Jun, Gao Xiao-Ming
exaly   +2 more sources

Numerical modeling and performance optimization of QEPAS spectrophone

SPIE Proceedings, 2012
22nd International Conference on Optical Fiber Sensors, Beijing, China, 15-19 Oct 2012The spectrophone performance for QEPAS is numerically investigated by using a finite element method.
Yingchun Cao, Jin, W, Wei Jin, Hoi Lut Ho, Cao, Y, Hoi, HL   +5 more
core   +2 more sources

GaSb Halbleiterlaser im Wellenlängenbereich 1, 9 µm - 2, 2 µm, deren Anwendungen in der QEPAS sowie deren Miniaturisierung [PDF]

, 2021
Die Messung von Spurengasen ist für viele Bereiche essentiell. So werden beispielsweise industrielle Verfahren anhand der Konzentration von Prozessgasen gesteuert oder ärztliche Diagnosen durch den Befund von Spurengasen im menschlichen Atem gefällt.
Milde, Tobias
core   +1 more source

Integrated near-infrared QEPAS sensor based on a 28 kHz quartz tuning fork for online monitoring of CO2 in the greenhouse

Photoacoustics, 2022
In this paper, a highly sensitive and integrated near-infrared CO2 sensor was developed based on quartz-enhanced photoacoustic spectroscopy (QEPAS).
Yihua Liu, Haoyang Lin, Baiyang Antonio Zhou Montano, Wenguo Zhu, Yongchun Zhong, Ruifeng Kan, Bin Yuan, Jianhui Yu, Min Shao, Huadan Zheng   +9 more
doaj   +1 more source

LED-Absorption-QEPAS Sensor for Biogas Plants [PDF]

Sensors, 2015
A new sensor for methane and carbon dioxide concentration measurements in biogas plants is presented. LEDs in the mid infrared spectral region are implemented as low cost light source. The combination of quartz-enhanced photoacoustic spectroscopy with an absorption path leads to a sensor setup suitable for the harsh application environment.
Köhring, Michael, Böttger, Stefan, Willer, Ulrike, Schade, Wolfgang   +3 more
openaire   +5 more sources

Parts-per-billion detection of carbon monoxide: A comparison between quartz-enhanced photoacoustic and photothermal spectroscopy

Photoacoustics, 2021
We report on a comparison between two optical detection techniques, one based on a Quartz-Enhanced Photoacoustic Spectroscopy (QEPAS) detection module, where a quartz tuning fork is acoustically coupled with a pair of millimeter-sized resonator tubes ...
Davide Pinto, Harald Moser, Johannes P. Waclawek, Stefano Dello Russo, Pietro Patimisco, Vincenzo Spagnolo, Bernhard Lendl   +6 more
doaj   +1 more source

Phase Optimized Photoacoustic Sensing of Gas Mixtures

Applied Sciences, 2020
In this paper, we report on the progress of the auto-triggered quartz-enhanced photoacoustic spectroscopy (QEPAS) technique which operates without external frequency generators and ensures permanent locking to the current resonance frequency of the ...
Mario Mordmueller, Simon Edelmann, Markus Knestel, Wolfgang Schade, Ulrike Willer   +4 more
doaj   +1 more source