Highly Sensitive T-Shaped Quartz Tuning Fork Based CH<sub>4</sub>-Light-Induced Thermoelastic Spectroscopy Sensor with Hydrogen and Helium Enhanced Technique
In this paper, a highly sensitive methane (CH<sub>4</sub>) sensor based on light-induced thermoelastic spectroscopy (LITES) and a T-shaped quartz tuning fork (QTF) with hydrogen (H<sub>2</sub>) and helium (He) enhancement techniques are reported for the first time. The low re...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-12-01
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| Series: | Sensors |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1424-8220/24/23/7743 |
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| Summary: | In this paper, a highly sensitive methane (CH<sub>4</sub>) sensor based on light-induced thermoelastic spectroscopy (LITES) and a T-shaped quartz tuning fork (QTF) with hydrogen (H<sub>2</sub>) and helium (He) enhancement techniques are reported for the first time. The low resonant frequency self-designed T-shaped QTF was exploited for improving the energy accumulation time. H<sub>2</sub> and He were utilized as surrounding gases for the T-shaped QTF to minimize energy loss, thereby enhancing the sensitivity of the LITES sensor. Additionally, a fiber-coupled multi-pass cell (FC-MPC) with a 40 m optical length was utilized to improve the optical absorption of CH<sub>4</sub>. The frequency response of the T-shaped QTF with different concentrations of H<sub>2</sub> and He was investigated, and the Q factor in the H<sub>2</sub> and He environment increased significantly. Compared to operating QTF in a nitrogen (N<sub>2</sub>) environment, the signal amplitude was enhanced by 2.9 times and 1.9 times in pure H<sub>2</sub> and He environments, respectively. This enhancement corresponded to a minimum detection limit (MDL) of 80.3 ppb and 113.6 ppb. Under different CH<sub>4</sub> concentrations, the T-shaped QTF-based H<sub>2</sub>-enhanced CH<sub>4</sub>-LITES sensor showed an excellent linear response. Furthermore, through Allan deviation analysis, the MDL of the T-shaped QTF-based H<sub>2</sub>-enhanced CH<sub>4</sub>-LITES can reach 38 ppb with an 800 s integration time. |
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| ISSN: | 1424-8220 |