Research on a novel magnetic-catalytic sensing material on CMOS-MEMS gas sensor

Abstract

In this research, a novel magnetic catalyzed SnO 2 with Mn 3 O 4 of CMOS-MEMS gas sensor is firstly proposed. Beyond the conventional heating methods to obtain high chemical reaction rate, the sensitivity of gas sensors can be enhanced by using our proposed magnetic catalysis technique at ultra-low power consumption. Fabrication of sensor structure is realized by the standard 0.35µm CMOS process and MEMS post process. Preparing for the magnetic sensing material, the solution of SnCl 4(aq) with powder of Mn 3 O 4 and the precursor is mixed to obtain sol-gel solution. Measurement of gas concentration of monoxide is arranged in the gas chamber with solenoidal coils using magnetic material, SnO 2 -Mn 3 O 4 coated onto a CMOS-MEMS gas sensor with donut-shaped stacked electrodes by horizontal magnetic field to facilitate sensitivity. Based on our mature CMOS-MEMS gas sensor structure and developed magnetic-catalytic sensing mechanism, the enhancement of sensitivity with SnO 2 -Mn 3 O 4 is investigated and formulated with the Gibbs free energy and the Eyric equation. According to a careful investigation of the measurement results, the sensitivity of proposed CO gas sensor reaches 1.87%/ppm under the 6 Gauss. Moreover, the sensitivity of the novel material SnO 2 -Mn 3 O 4 is better than our previous research with sensing material SnO 2 -Fe 3 O 4 . This research shows a highly practical application to CMOS gas sensor with a widespread magnetic-catalytic mechanism and sol-gel solution.