Self-Heating Gas Sensor Using Heterojunction Nanowire Array for High Sensitivity and Low Power Consumption

This paper reports a novel heterojunction nanowire array for a self-heating gas sensor with high sensitivity and low power consumption. Compared to the conventional self-heating gas sensors where the entire device is made up of a single sensing material, the proposed method employs an innovatively constructed metal/metal-oxide/metal (M-O-M) heterojunction design. The metal nanowires on both ends of the metal-oxide nanowires not only elongate the thermal heat loss pathway but also allow thermal activation at the sensing region to its entirety, resulting in low power consumption and high/stable gas responsivity. We theoretically and experimentally demonstrated that the proposed design operates with about 5-times lower power consumption when compared to that of the conventional design. Additionally, in comparison to its predecessor, the heterojunction architecture achieved about 2.5-times higher sensitivity while also showing stable recovery after each exposure to toxic gas.