Methane detection with high temperature all-silicon microheater

Detection of methane (CH4) below the Lower Explosive Limit (LEL) with large-signal output based on thermal conduction was demonstrated by an ultra-high temperature all-silicon cantilever-type microheater. Thermal conductivity measurement is powerful for gas sensing in chromatography, however, the thermal conductivity method is nearly never used for detection of the methane below the LEL in coal mine due to deficiency in sensitivity. In this paper, a cantilever-type all-silicon microheater with high temperature capability was designed and fabricated from Silicon-On-Insulator (SOI) substrate; and corresponding output signal at least 10 mV for per 1 vol% methane was obtained in the range from 0~5 vol%. It offers the potential application in underground coal mining for monitoring the methane concentration below the LEL with replacement of the bead-type catalytic pellistor devices.