Highly Selective and Sensitive Ag-Based Hydrogen Sulfide Gas Sensor Based on Precise Chip Temperature Management

Hydrogen sulfide (H₂S) detection with a high selectivity and fast response is necessary due to its strong toxicity both to the environment and humans. In this article, we present design, fabrication, and characterization of a Silver (Ag)-based H2S gas sensor, in which the temperature uniformity of sensitive materials has an important effect on their detection sensitivity, selectivity and reliability. Therefore, we introduce a new type of micro-hotplate chip design with an isothermal hot area (± 15 °C at 350 °C) accounts for 90% of the total heating area of the sensor, effectively resolving the issue of area uniform heating in gas sensor design. Results show that a response time for 100 ppm H2S is around 2 s under 350 °C operating temperature, and the limit of detection (LOD) is 134 parts-per-billion (ppb) in ambient conditions. Moreover, selectivity tests indicate that the sensor has poor response to interfering analytes such as hydrogen, methane, carbon monoxide, ammonia, and sulfur dioxide, and their average selectivity coefficients of H2S are greater than 88. This Ag-based H2S sensor offers advantages such as remarkable potential for mass production due to its easy to manufacture and high performance.