Fast Nitrogen Dioxide Sensing with Ultralow-Power Nanotube Gas Sensors

The study reports fast, ultralow-power operation of carbon nanotube-based nitrogen dioxide (NO2) sensors enabled by nanotube self-heating and transient sensing. The self-heating effect in the nanotube channel significantly accelerates the desorption of gas molecules, reducing the sensor recovery time to a minute. As gas molecules re-adsorb on the nanotube after cooling, the initial rate of the sensor transient is used to determine NO2 concentration within a few minutes. To accelerate and optimize the operation of the sensor, the study considered temperature profiles along the self-heated carbon nanotube, their effect on different sensing regions, and a physical model-based fit. As a result, the nanotube-based NO2 sensor demonstrates recovery and readout times below 5 min and an extrapolated limit of detection below 10 ppb. The peak power consumption of this operation mode is below 6 mu W. The combination of fast readout, fast recovery, low limit of detection, and ultralow power consumption demonstrated in this work shows strong promise of carbon nanotube-based NO2 sensors in mobile or Internet-of-Things (IoT) applications.