Research on a Highly Sensitive Magnetic-Catalytic CMOS-MEMS Compatible Gas Sensor

This letter proposes a new magnetic-catalytic sensing mechanism designed to increase the sensitivity of a gas sensor with mesh-stacked sensing electrodes. Beyond the conventional power dissipation of heating to maintain a certain working temperature, the novel gas sensor with a magnetic-catalytic mechanism operates at an ambient temperature, and heating power does not need to be considered. The standard 0.35 μm CMOS process was used to fabricate a gas sensor with mesh-stacked electrodes. To prepare the magnetic sensing material, a SnO₂ solution, prepared using the sol-gel method, was mixed with Fe₃O₄ at a ratio of SnO₂:Fe₃O₄=3:1 and was deposited onto mesh-stacked electrodes. When the CO gas sensor was introduced, the sample was tested and verified inside a CO gas chamber using a magnetic field generator composed of solenoidal coils. According to a careful investigation of the measurement results, the highest sensitivity, 1.73%/ppm, was obtained under 12 G in a horizontal magnetic field, indicating that the mechanism is applicable for use in an ultralow power chemical microsensor with high sensitivity.