Research of oriented ceramic nanotube array full range methane sensors based on MEMS technology used for wireless monitoring networks
Xin-Lei Liu, Qiang Wu, Bin Shen, Hong-Quan Zhang, Hong-Liang Wang and Sheng-Wu Cao
Abstract: Aiming at solving problem of full range wireless detection of methane gas in coal mine, an integrated gas detection method based on oriented nanotube ceramic plate is proposed. The γ-Al2O3 substrate with directional porous structure was prepared by double anodizing method, and a three-unit micro cantilever structure detection element was fabricated by MEMS technology. After screen printing to form Pt heating electrode pattern, in-situ printing technology to load Pd-Pt composite catalyst, isolation structure packaging and other processes, the array type full range methane sensor was made. By using COMSOL finite element simulation, the multi field coupling research of the sensor array element was carried out, and the gas response characteristics of the sensor were further measured. The test results show that the designed gas sensor has characteristics of fast response to methane gas with a 90% response time of 8s and a 90% recovery time of 7s, full range detection with the average sensitivity of 12.2mv/1%CH4 at low concentration (< 5%) and 27.1mv/10%CH4 at high concentration (≥ 5%). There is a good linear relationship between the sensor output and methane concentration, but non relationship between its response & recovery time and its working voltage as well as target gas concentration. The research results indicate that the integrated sensor will be beneficial to the application of gas monitoring the Internet of things in coal mines.
Keywords: Internet of things, Full range methane sensor, MEMS, Oriented nanotube ceramic plate, Response time