Nanostructured Metal Oxide for High-Performance Electronic Nose

Nanostructured metal oxide-based electronic noses (E-nose) have garnered significant attention due to their impressive sensor response, rapid response/recovery times, and, most notably, their exceptional selectivity. These E-noses can be assembled using a single metal oxide or a gas sensor array based on metal oxides or MEMS technology, particularly when combined with machine-learning algorithms, to detect small-molecule gases and VOCs. In this review, we have summarized and compared the exceptional performance of these metal oxide-based E-noses, highlighting their advantages in gas detection. We have explored their wide-ranging applications, including monitoring indoor and outdoor air quality, identifying volatile liquids, assessing the freshness of food, and diagnosing diseases. Furthermore, we have discussed the potential challenges and prospects for metal oxide-based E-noses. It is evident from our review that nanostructured metal oxides hold great promise as potential candidates for assembling E-noses that exhibit excellent gas-sensing capabilities.