The study on methane sensing with high-temperature low-power CMOS compatible silicon microheater

- A high temperature approach for LEL methane detection was proposed and achieved.
- High sensitivity (22 mV/1%CH4) and good linearity was obtained without amplifier.
- The heating power is about 50 mW, and it can be greatly reduced under pulse mode.
- Sensitive consistency under flow rates indicates a perfect sensitivity stability.
- Merits also include fast, intrinsic safety, anti contamination and CMOS compatible.

A high-temperature silicon cantilever microheater with low power consumption was proposed for detection of low concentrations of methane gas. The microheater was designed and fabricated on SOI (Silicon-On-Insulator) wafer. Usually, methane at low concentrations (below the lower explosive limit) is almost imperceptible when using the thermal conduction method. Compared to other methane sensing technologies, the thermal conduction detection method possesses unique features that could best meet the requirements of the Internet of Things. In this research, the methane sensing temperature of the thermal conduction method increased to above 600 °C by using the proposed microheater, which has a low power consumption of about 50 mW. Relying on the high heating temperature and the high-temperature induced increment both in methane thermal conductivity and in the temperature coefficient of resistance of the microheater, a high sensitivity of about 22 mV/1% CH4 was obtained without using an amplifier. Experiment also shows that the proposed microheater would be a self-cleaning and intrinsically safe device. The CMOS-compatible fabrication process would enable the silicon microheater to be batch fabricated and monolithically integrated with peripheral circuits, eventually lowering production costs.

96