Frequency-Domain Detection for Frequency-Division Multiplexing QEPAS
To achieve multi-gas measurements of quartz-enhanced photoacoustic spectroscopy (QEPAS) sensors under a frequency-division multiplexing mode with a narrow modulation frequency interval, we report a frequency-domain detection method. A CH<sub>4</sub> absorption line at 1653.72 nm and a CO...
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MDPI AG
2022-05-01
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| Series: | Sensors |
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| Online Access: | https://www.mdpi.com/1424-8220/22/11/4030 |
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| author | Xiang Chen Hao Liu Mai Hu Lu Yao Zhenyu Xu Hao Deng Ruifeng Kan |
| author_facet | Xiang Chen Hao Liu Mai Hu Lu Yao Zhenyu Xu Hao Deng Ruifeng Kan |
| author_sort | Xiang Chen |
| collection | DOAJ |
| description | To achieve multi-gas measurements of quartz-enhanced photoacoustic spectroscopy (QEPAS) sensors under a frequency-division multiplexing mode with a narrow modulation frequency interval, we report a frequency-domain detection method. A CH<sub>4</sub> absorption line at 1653.72 nm and a CO<sub>2</sub> absorption line at 2004.02 nm were investigated in this experiment. A modulation frequency interval of as narrow as 0.6 Hz for CH<sub>4</sub> and CO<sub>2</sub> detection was achieved. Frequency-domain 2<i>f</i> signals were obtained with a resolution of 0.125 Hz using a real-time frequency analyzer. With the multiple linear regressions of the frequency-domain 2<i>f</i> signals of various gas mixtures, small deviations within 2.5% and good linear relationships for gas detection were observed under the frequency-division multiplexing mode. Detection limits of 0.6 ppm for CH<sub>4</sub> and 2.9 ppm for CO<sub>2</sub> were simultaneously obtained. With the 0.6-Hz interval, the amplitudes of QEPAS signals will increase substantially since the modulation frequencies are closer to the resonant frequency of a QTF. Furthermore, the frequency-domain detection method with a narrow interval can realize precise gas measurements of more species with more lasers operating under the frequency-division multiplexing mode. Additionally, this method, with a narrow interval of modulation frequencies, can also realize frequency-division multiplexing detection for QEPAS sensors under low pressure despite the ultra-narrow bandwidth of the QTF. |
| first_indexed | 2024-03-10T00:53:53Z |
| format | Article |
| id | doaj.art-78aa0a08f85e48fc846d18d4504b5e85 |
| institution | Directory Open Access Journal |
| issn | 1424-8220 |
| language | English |
| last_indexed | 2024-03-10T00:53:53Z |
| publishDate | 2022-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Sensors |
| spelling | doaj.art-78aa0a08f85e48fc846d18d4504b5e852023-11-23T14:47:34ZengMDPI AGSensors1424-82202022-05-012211403010.3390/s22114030Frequency-Domain Detection for Frequency-Division Multiplexing QEPASXiang Chen0Hao Liu1Mai Hu2Lu Yao3Zhenyu Xu4Hao Deng5Ruifeng Kan6Jinlin Institute of Technology, Nanjing 211169, ChinaHefei Institute of Physical Science, Chinese Academy of Sciences, Hefei 230031, ChinaHefei Institute of Physical Science, Chinese Academy of Sciences, Hefei 230031, ChinaHefei Institute of Physical Science, Chinese Academy of Sciences, Hefei 230031, ChinaHefei Institute of Physical Science, Chinese Academy of Sciences, Hefei 230031, ChinaHefei Institute of Physical Science, Chinese Academy of Sciences, Hefei 230031, ChinaHefei Institute of Physical Science, Chinese Academy of Sciences, Hefei 230031, ChinaTo achieve multi-gas measurements of quartz-enhanced photoacoustic spectroscopy (QEPAS) sensors under a frequency-division multiplexing mode with a narrow modulation frequency interval, we report a frequency-domain detection method. A CH<sub>4</sub> absorption line at 1653.72 nm and a CO<sub>2</sub> absorption line at 2004.02 nm were investigated in this experiment. A modulation frequency interval of as narrow as 0.6 Hz for CH<sub>4</sub> and CO<sub>2</sub> detection was achieved. Frequency-domain 2<i>f</i> signals were obtained with a resolution of 0.125 Hz using a real-time frequency analyzer. With the multiple linear regressions of the frequency-domain 2<i>f</i> signals of various gas mixtures, small deviations within 2.5% and good linear relationships for gas detection were observed under the frequency-division multiplexing mode. Detection limits of 0.6 ppm for CH<sub>4</sub> and 2.9 ppm for CO<sub>2</sub> were simultaneously obtained. With the 0.6-Hz interval, the amplitudes of QEPAS signals will increase substantially since the modulation frequencies are closer to the resonant frequency of a QTF. Furthermore, the frequency-domain detection method with a narrow interval can realize precise gas measurements of more species with more lasers operating under the frequency-division multiplexing mode. Additionally, this method, with a narrow interval of modulation frequencies, can also realize frequency-division multiplexing detection for QEPAS sensors under low pressure despite the ultra-narrow bandwidth of the QTF.https://www.mdpi.com/1424-8220/22/11/4030photoacoustic spectroscopyquartz tuning forkfrequency-division multiplexingfrequency-domain signal |
| spellingShingle | Xiang Chen Hao Liu Mai Hu Lu Yao Zhenyu Xu Hao Deng Ruifeng Kan Frequency-Domain Detection for Frequency-Division Multiplexing QEPAS Sensors photoacoustic spectroscopy quartz tuning fork frequency-division multiplexing frequency-domain signal |
| title | Frequency-Domain Detection for Frequency-Division Multiplexing QEPAS |
| title_full | Frequency-Domain Detection for Frequency-Division Multiplexing QEPAS |
| title_fullStr | Frequency-Domain Detection for Frequency-Division Multiplexing QEPAS |
| title_full_unstemmed | Frequency-Domain Detection for Frequency-Division Multiplexing QEPAS |
| title_short | Frequency-Domain Detection for Frequency-Division Multiplexing QEPAS |
| title_sort | frequency domain detection for frequency division multiplexing qepas |
| topic | photoacoustic spectroscopy quartz tuning fork frequency-division multiplexing frequency-domain signal |
| url | https://www.mdpi.com/1424-8220/22/11/4030 |
| work_keys_str_mv | AT xiangchen frequencydomaindetectionforfrequencydivisionmultiplexingqepas AT haoliu frequencydomaindetectionforfrequencydivisionmultiplexingqepas AT maihu frequencydomaindetectionforfrequencydivisionmultiplexingqepas AT luyao frequencydomaindetectionforfrequencydivisionmultiplexingqepas AT zhenyuxu frequencydomaindetectionforfrequencydivisionmultiplexingqepas AT haodeng frequencydomaindetectionforfrequencydivisionmultiplexingqepas AT ruifengkan frequencydomaindetectionforfrequencydivisionmultiplexingqepas |