Highly Sensitive Photoacoustic Microcavity Gas Sensor for Leak Detection.

Ke Chen,Hong Deng,Shuai Liu,Bo Zhang,Fengxiang Ma,Liang Mei,Zhenfeng Gong,Min Guo,Qingxu Yu,Yewei Chen

doi:10.3390/s20041164

Abstract

A highly sensitive photoacoustic (PA) microcavity gas sensor for leak detection is proposed. The miniature and low-cost gas sensor mainly consisted of a micro-electro-mechanical system (MEMS) microphone and a stainless-steel capillary with two small holes opened on the side wall. Different from traditional PA sensors, the designed low-power sensor had no gas valves and pumps. Gas could diffuse into the stainless-steel PA microcavity from two holes. The volume of the cavity in the sensor was only 7.9 μL. We use a 1650.96 nm distributed feedback (DFB) laser and the second-harmonic wavelength modulation spectroscopy (2f-WMS) method to measure PA signals. The measurement result of diffused methane (CH4) gas shows a response time of 5.8 s and a recovery time of 5.2 s. The detection limit was achieved at 1.7 ppm with a 1-s lock-in integral time. In addition, the calculated normalized noise equivalent absorption (NNEA) coefficient was 1.2 × 10−8 W·cm−1·Hz−1/2. The designed PA microcavity sensor can be used for the early warning of gas leakage.

Highlights

Gas leak detection plays an important role in the safety monitoring of gas pipelines, chemical plants, coal mines, and residential buildings [1,2,3,4,5]
The modulated laser light is injected into the microcavity the single-mode fiber to excite the PA pressure wave, which is detected by the micro-electro-mechanical system (MEMS) microphone through the single-mode fiber to excite the PA pressure wave, which is detected by the MEMS
The designed PA gas sensor mainly consisted of a stainless-steel capillary and a MEMS microphone

Summary

Introduction

Gas leak detection plays an important role in the safety monitoring of gas pipelines, chemical plants, coal mines, and residential buildings [1,2,3,4,5]. The leakage of flammable or explosive gases, such as natural gas, can cause serious safety incidents. Trace diffuse gas detection provides an effective method for the early warning of these accidents

Methods

Discussion

Conclusion