Ppb-level detection of methane based on an optimized T-type photoacoustic cell and a NIR diode laser

Zhenfeng Gong; Tianli Gao; Liang Mei; Ke Chen; Yewei Chen; Bo Zhang; Wei Peng; Qingxu Yu

doi:10.1016/j.pacs.2020.100216

Ppb-level detection of methane based on an optimized T-type photoacoustic cell and a NIR diode laser

Photoacoustics. 2020 Dec 16:21:100216. doi: 10.1016/j.pacs.2020.100216. eCollection 2021 Mar.

Authors

Zhenfeng Gong^{1

2}, Tianli Gao¹, Liang Mei¹, Ke Chen¹, Yewei Chen¹, Bo Zhang¹, Wei Peng³, Qingxu Yu¹

Affiliations

¹ School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology, Dalian, 116024, Liaoning, China.
² Tbea Electric Co., Ltd., Changji, 831100, Xinjiang, China.
³ School of Physics, Dalian University of Technology, Dalian, 116024, Liaoning, China.

Abstract

This paper presents an optimized T-type resonant photoacoustic (PA) cell for methane (CH₄) gas detection. The noise transmission coefficients and PA field distributions of the T-type resonant PA cell have been evaluated using the finite element method and thermoviscous acoustic theory. The optimized T-type resonant PA cell, together with a near-infrared (NIR) distributed feedback (DFB) laser source, a high-speed spectrometer and a fiber-optic acoustic sensor constitutes a PAS system for CH₄ detection. The sensitivity is measured to be 1.8 pm/ppm and a minimum detectable limit (MDL) of 9 parts per billion (ppb) can be achieved with an averaging time of 500 s. The optimized T-type longitudinal resonant PA cell features of high PA cell constant, fast response time and simple manufacturing process.

Keywords: Fiber-optic acoustic sensor; Methane; Photoacoustic spectroscopy; T-type resonant photoacoustic cell.