Development of a Ferrite Film Based Solid State Sensor System for Ultra Low Concentration Hydrogen Sulfide Gas Detection

Abstract

We report on a selective hydrogen sulfide gas sensor based on zinc ferrite film which is obtained by a microwave-assisted solvothermal deposition route. The response of the chemiresistive device is found to be in the range of 1872% - 90% for 5.6 ppm – 0.3 ppm of H₂S gas at an operating temperature of 250°C. The density functional theory studies suggest physisorption of the H₂S molecules at the partially-inverted ZnFe₂O₄ surface as the reason behind the fast rise (of the order of ~40 sec) and fall time (of the order of ~70 sec) with complete recovery of the device. Finally, a dual-differential subtractor based auto-balancing interface circuit is proposed to drive this sensor which is advantageous in terms of accuracy and particularly suitable for a device such as ours, which has a wide dynamic range.