Recent advances in laser gas sensors for applications to safety monitoring in intelligent coal mines

Abstract

Due to the extremely complex working conditions, various health and safety hazards are present in underground coal mines, which cause economic losses and heavy casualties. Among these hazards, methane gas explosion and coal combustion are recognized as the two major hazards to miners. Traditional electronic sensors in mine safety monitoring systems have problems such as low precision, a large amount of maintenance, and monitoring dead zones. In the past decade, gas sensors based on tunable diode laser absorption spectroscopy (TDLAS) have been extensively studied and tailored for use in the coal mine industry because of their advantages of high sensitivity, high stability, fast response, intrinsic safety, and remote monitoring. This invited paper introduces the recent progress and typical applications of TDLAS-based methane sensors, carbon monoxide sensors, and multi-gas monitoring systems in coal mine gas monitoring, fire prevention, and early warning in intelligent coal mines.

Gas nanosensors for health and safety applications in mining

“…Popular mining gas sensors include sensors based on thermal conductivity 60 and catalytic combustion, 77 tunable diode laser absorption spectroscopy (TDLAS) sensors, 2 and non-dispersive infrared (NDIR), 78 and electrochemical sensors. 55 Optical spectroscopic sensors such as TDLAS and NDIR sensors require large and expensive equipment and are challenging to integrate into portable or wearable optoelectronics.…”

“… 1 The working environments in underground mines are known for their complexity and harshness with some hazards arising directly from various combinations of gaseous chemicals. 2 The dynamic and tough mining environments pose serious challenges in maintaining occupational health and safety (OHS) of the workers in mines. A fatality rate of 2.9 per 100 000 was reported for Australia's mines in 2019.…”

Design of single-laser remote methane gas measurement system with distance measurement based on time-division multiplexing technology

“…Due to the long-distance traveling and directional properties of laser, TDLAS technology has been widely used in remote methane concentration measurement and shows great advantages over traditional types of sensors catalytic combustion and semiconductors [2][3] . However, limited by the measurement principle, the current remote methane measurement system can only obtain the integral concentration of the laser path.…”

Machine learning‐assisted wearable sensor array for comprehensive ammonia and nitrogen dioxide detection in wide relative humidity range

“…9,10 Recently, with the help of 5G communication and big data, the emergence and fast booming of wearable electronics and sensors bring up a promising concept of intelligent mining and mining healthcare. [11][12][13][14][15] A tremendous amount of metal oxide semiconductor (MOS) gas sensors, based on the sensing mechanism of the double Schottky barrier model, such as SnO 2 , WO 3 , TiO 2 , and ZnO, have been extensively developed for the detection of NH 3 and NO 2 gases. 16,17 Although these sensors exhibited high sensitivity and stability under single gas environments, poor selectivity and difficulties in wearable device fabrication due to high operating temperature are two larger barriers to their applications in mixing gas conditions.…”