Toward practical gas sensing with rapid recovery semiconducting carbon nanotube film sensors

Nanomaterials have been considered as promising materials to construct highly sensitive and miniaturized gas sensors due to their high ratio of surface to volume, but almost all of the reported nanomaterials based resistive gas sensors are difficult to use in the practical system mainly owing to the long recovery time and non-equilibrium state at room temperature. Here, we demonstrate a gate assistant technology to realize the rapid recovery to an equilibrium state in semiconducting carbon nanotube (CNT) thin-film gas sensors and promote the CNT-based gas sensors to reach the practical application level. Specifically, we construct highly uniform gas sensors based on semiconducting solution-derived CNT film and accelerate the gas molecules desorption by applying a voltage on the back gate (substrate), which is named gate-assistant recovery technology. By combining the gate-assistant recovery technology and a modified concentration calculation method, highly reproducible detection systems have been realized by using a custom-built printed circuit board (PCB) based data acquisition circuits to execute a real-time rapid detection of H-2 in the air at room temperature, and especially exhibits a record response time of 9 s and recovery time of 50 s under a resolution of 10 ppm, which outperformed previous low dimensional nanomaterials based portable H-2 detection systems. The gate-assistant rapid recovery and related concentration calculation technologies are helpful to promote the nanomaterials-based gas sensors to practical application for highly sensitive online gas detection.