Improved Selectivity and Sensitivity of Gas Sensing Using a 3D Reduced Graphene Oxide Hydrogel with an Integrated Microheater

Low-cost, one-step, and hydrothermal synthesized 3D reduced graphene oxide hydrogel (RGOH) is exploited to fabricate a high performance NO₂ and NH₃ sensor with an integrated microheater. The sensor can experimentally detect NO₂ and NH₃ at low concentrations of 200 ppb and 20 ppm, respectively, at room temperature. In addition to accelerating the signal recovery rate by elevating the local silicon substrate temperature, the microheater is exploited for the first time to improve the selectivity of NO₂ sensing. Specifically, the sensor response from NH₃ can be effectively suppressed by a locally increased temperature, while the sensitivity of detecting NO₂ is not significantly affected. This leads to good discrimination between NO₂ and NH₃. This strategy paves a new avenue to improve the selectivity of gas sensing by using the microheater to raise substrate temperature.