Low-cost,
one-step, and hydrothermal synthesized 3D reduced graphene
oxide hydrogel (RGOH) is exploited to fabricate a high performance
NO<sub>2</sub> and NH<sub>3</sub> sensor with an integrated microheater.
The sensor can experimentally detect NO<sub>2</sub> and NH<sub>3</sub> 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 NO<sub>2</sub> sensing. Specifically, the sensor response from NH<sub>3</sub> can be effectively suppressed by a locally increased temperature,
while the sensitivity of detecting NO<sub>2</sub> is not significantly
affected. This leads to good discrimination between NO<sub>2</sub> and NH<sub>3</sub>. This strategy paves a new avenue to improve
the selectivity of gas sensing by using the microheater to raise substrate
temperature